Journal of Manufacturing and Materials Processing doi: 10.3390/jmmp10100414

Authors: Abimbola Ojomo Kenneth Looby Peter Omoniyi Olu Bamiduro Nadir Yilmaz Horace Whitworth Gbadebo Owolabi

Nickel-based superalloys remain the material of choice for gas turbine engines, nuclear reactors, and other extreme environment applications because they retain their exceptional tensile strength, creep resistance and fatigue performance at critical temperatures reaching or exceeding 80% of their melting point. This extraordinary behavior arises from carefully engineered finely tuned dual-phase (γ/γ′) microstructure, developed through decades of alloy design, processing innovation, and mechanistic understanding. This review examines the coupled roles of alloy design, manufacturing and in service degradation in long term performance and failure. Emphasis is made on how processing induced microstructural features, which include segregation, grain morphology, residual stress, porosity, precipitate distributions, and interface structures, can influence tensile deformation, creep damage, oxidation, and fatigue crack initiation and growth during service. Conventional wrought processing methods are evaluated alongside emerging additive manufacturing routes which both challenge the established alloy design rules and increase complex geometries. Recently, advances concerning size effects, heterostructure interfaces, and interacting damage, especially the coupling of creep, fatigue, and oxidation, are integrated within a single framework connecting processing history to service behavior. This review argues that the most important unsolved problems do not lie in the alloy design, manufacturing, or failure mechanisms individually (including tensile overload, creep rupture, and fatigue crack growth), but in predicting and controlling their interactions across the life cycle of the material. Design strategies based on solid solution strengthening, precipitation hardening, grain boundary engineering, and environmental resistance are therefore discussed as responses to specific degradation and failure risks across microstructural architectures ranging from equiaxed polycrystals to directionally solidified and single crystal forms.

Journal of Manufacturing and Materials Processing doi: 10.3390/jmmp10100413

Authors: Maximilian Janek Moritz Weisenfeld Lars Larsen Michael Kupke

Ultrasonic welding of carbon-fibre-reinforced polymers delivers fast, high-quality joints and scales well to automated, high-rate production. In continuous welding, the progressing weld seam constantly changes the boundary conditions, especially in respect to ultrasonic welding. For this reason, it is particularly important for applications in the aerospace sector that the continuous ultrasonic welding process is actively controlled, especially when a thorough and robust weld seam quality is required. This short communication introduces a novel control method where material feedback (temperature) is incorporated as a reference variable by using an infrared thermography camera as a feedback sensor in a closed-loop controller. Furthermore, this study presents preliminary results, such as improved process robustness and repeatability compared with conventional process control methods, such as constant-amplitude or constant-power control. These results were evaluated using destructive and non-destructive testing methods and form the basis for further, in-depth analyses in future experiments.

Journal of Manufacturing and Materials Processing doi: 10.3390/jmmp10100412

Authors: M. M. Suyundikov R. A. Begaliyev P. O. Bykov A. V. Bogomolov A. B. Kuandykov A. K. Zhunusov

The oil and gas industry needs seamless steel pipes resistant to hydrogen-induced cracking, driven by the development of increasingly complex, deep, and high-pressure fields, oil production with high hydrogen sulfide content, and the growing number of hydrogen-based decarbonization projects. The aim of the work was to investigate the mechanism of formation of non-metallic inclusions in 13ChFA-grade steel that are potentially significant for HIC pipe steel, a low-alloy steel similar to AISI 5115, and to develop steelmaking-process modifications that improve its resistance to hydrogen-induced cracking. Non-metallic inclusions in seamless-pipe samples were examined by micro-X-ray spectral analysis across 11 laboratory protocols comprising 213 spectra. Based on the identified inclusion-formation mechanism, process modifications were developed and tested in five pilot heats at the electric-arc-furnace, ladle-furnace, and vacuum-degassing stages; the effect was verified on samples from serial production. Resistance to hydrogen-induced cracking was evaluated according to the NACE TM0284-2011 standard, and inclusion content according to the GOST 1778 standard. In 8 of the 11 cases of defects examined (≈73%), the recorded steelmaking defects were associated with two types of inclusions potentially significant for HIC: endogenous conglomerates of magnesian spinel, calcium aluminate, and sulfide phases (about 45%), and manganese–iron silicate films (about 27%); the remaining 27% were exogenous slag inclusions. Reducing the oxygen content before tapping, increasing the addition of lime and fluorspar, limiting the metal residence time in the ladle, and controlling the calcium-to-sulfur ratio during secondary treatment yielded pilot heats with zero crack sensitivity, crack length, and crack thickness ratios, while inclusion content complied with the steel-cleanliness standard. In a series of five trial heats—conducted without a parallel control group—a consistent relationship was observed between controlled ladle treatment parameters, the type and quantity of inclusions potentially significant for HIC, and a standardized hydrogen-induced cracking resistance index. The resulting set of process modifications, tested under industrial conditions across five heats, represents a practical approach to enhancing the resistance of low-alloy pipe steels to hydrogen cracking.

Journal of Manufacturing and Materials Processing doi: 10.3390/jmmp10100411

Authors: Mana Saedan Watcharapong Tachajapong

Fused deposition modeling (FDM) parts show condition-dependent variability in ultimate tensile strength (UTS), yet most machine learning (ML) studies report only deterministic point estimates, limiting use in safety-critical design. This work presents a probabilistic framework mapping FDM-PETG process parameters to orientation-specific conditional quantile estimates with pooled uncertainty, covering model selection, deployment, and process optimization. A controlled experiment varied 12 parameters across 111 printing conditions from a combined Taguchi and Latin Hypercube Sampling (LHS) design, yielding 333 ASTM D3039 tensile measurements. Six probabilistic models were trained on raw replicate data and ranked on point accuracy and calibration, weighted 75% toward uncertainty quantification (UQ). The mixture density network (MDN) showed the lowest composite rank. Orientation-specific (MDN-OR) and unified (MDN-UF) variants were compared; MDN-OR gave more conservative lower-quantile estimates for safety-critical design. Lower-quantile (q = 0.05) SHAP analysis identified filament consumption and wall loops as the strongest predictive associations with worst-case strength. For each orientation, the configuration with minimum filament consumption at maximum strength was selected, with its post hoc q = 0.05 lower bound confirmed by physical tensile testing. Within the studied single-material, single-printer setting, the framework shows how probabilistic process–property modeling can support uncertainty-aware parameter selection toward autonomous additive manufacturing.

Journal of Manufacturing and Materials Processing doi: 10.3390/jmmp10100410

Authors: Ammar Ibrahim Abdulwahid Mehran Mahboubkhah Reza Najjar

Polypropylene (PP) is a promising feedstock for extrusion-based additive manufacturing due to its low density and chemical resistance; however, its semicrystalline nature induces shrinkage and warpage during printing. This study investigates how hybrid carbon nanotube (CNT)–graphene oxide (GO) architectures influence the mechanical, thermal, melt flow, and dimensional behavior of PP during material extrusion (MEX) and fused granule fabrication (FGF). Neat PP, single-filler controls, and hybrid CNT–GO formulations (total filler ≤ 2 wt.%) were prepared via solvent-assisted dispersion and characterized by tensile/flexural testing, thermal analysis, spectroscopy, microscopy, melt flow index, and warpage measurements. CNT–GO incorporation increased tensile and flexural modulus and strength by up to 55%/57% and 71%/71%, respectively, while reducing ductility. Thermal stability and crystallinity improved, consistent with heterogeneous nucleation. Network development reduced melt flow index, increased apparent flow activation energy, and reduced warpage by up to 58% for the balanced 1:1 CNT: GO formulation. These formulation-dependent trends establish a common material-level link between reinforcement and printability. MEX and FGF showed broadly similar performance under the investigated conditions, with no statistically significant route effect detected for most properties; the balanced hybrid formulation provided the best overall balance between mechanical properties and dimensional stability.

Journal of Manufacturing and Materials Processing doi: 10.3390/jmmp10100409

Authors: Laura Antonini Claudio Giardini

Stretch-reducing mills are complex multi-stand systems in which the final tube thickness depends on the interaction between inter-stand tensions, angular speeds, material deformation, and process conditions. In this study, a multi-task neural network is proposed to model and optimize the operation of a six-stand stretch-reducing mill. A structured pipeline was used to generate a feasible dataset to train and test the model. The proposed architecture employs the inter-stand tensions in input, utilizes a shared network to get the general relationships between variables, and predicts process status, tube thickness, angular speed, and the neutral radius of each stand with dedicated task-specific heads. The model achieved high performance across all the tasks on training, validation, and testing sets. The final tube thickness predictions get a very low error, showing the ability of the proposed network to gather hidden relationships throughout the process. The trained model was integrated with the differential evolution optimization algorithm to obtain the feasible inter-stand distribution and stand angular speeds to achieve the desired final tube thickness while respecting the feasibility constraint set. The results demonstrate that the proposed framework can provide support for the decision-making process optimization, representing an effective tool for intelligent modeling in stretch-reducing mill monitoring and control.

Journal of Manufacturing and Materials Processing doi: 10.3390/jmmp10100408

Authors: Bauyrzhan Rakhadilov Nurtoleu Magazov Aidar Kengesbekov Dauir Kakimzhanov

This study examines the relationships between kerosene pump frequency, in-flight particle temperature and velocity, phase composition, porosity, roughness, and mechanical properties of HVOF-sprayed WC–12Co coatings. In the primary series, the pump frequency was varied from 30 to 37 Hz, while the nominal oxygen settings, carrier-gas flow rate, spray distance, and robot program remained constant. Between the boundary conditions, the mean particle temperature increased from 1685 to 1719 °C and the mean velocity from 681 to 754 m/s. The W2C/WC ratio increased from 0.0160 to 0.0341. Porosity decreased from 2.62% for F30 to 1.95% and 1.88% for F33 and F35, respectively, before increasing to 2.45% for F37. F35 exhibited the highest mean hardness and indentation modulus; however, pairwise comparisons did not identify significant hardness differences among F33, F35, and F37. In an additional series at 30–34–34–37 Hz, the coatings deposited at the intermediate frequency also had lower mean porosity than those deposited at the boundary frequencies. These results associate the combined changes in particle thermal and kinetic conditions with coating densification and mechanical response at intermediate spraying conditions.

Journal of Manufacturing and Materials Processing doi: 10.3390/jmmp10100407

Authors: Rabiul Islam Kevin Chou

Porosity in laser powder bed fusion (L-PBF) lattice struts remains poorly understood, as the effects of build angle and process parameters are often studied separately. A full factorial design of 27 configurations combined three build angles (40–70°), three strut sizes (0.25–1.25 mm), and three linear energy densities (LED: 0.23–0.35 J/mm). Specimens were fabricated in Ti-6Al-4V on an EOS M270 system and characterized by micro-computed tomography (µ-CT). Statistical analysis showed that all three factors influenced porosity percentage (P%), with a significant size–LED interaction, while only strut size and LED influenced the average volume of individual pores (PVavg), with no significant interactions. P% rose 194% as strut diameter increased from 0.25 to 1.25 mm, climbed steeply between 0.23 and 0.29 J/mm before plateauing, and fell 19% as build angle increased from 40° to 70°. PVavg rose 160% across the LED range and 37% with strut diameter. Spatial segmentation showed that the median down-skin-to-up-skin pore volume ratio in the larger struts fell from 2.0 at 40°, that is, twice the pore volume in the DS region, to 1.3 at 70°. This asymmetry was absent in the 0.25 mm struts, where low pore counts made the metric unreliable.

Journal of Manufacturing and Materials Processing doi: 10.3390/jmmp10100406

Authors: Yuyao Zhu Shiro Ihara Mitsuhiro Murayama

Scanning precession electron diffraction in transmission electron microscopy (TEM-SPED) enables highly accurate nanoscale orientation mapping and facilitates time-resolved tracking of microstructural changes, including grain boundary migration in polycrystalline metallic materials during isothermal or isochronal heat treatments. However, fully predicting grain boundary migration behavior requires further advances, including the integration of experimental observations with computational simulations. In this study, we addressed this challenge by directly assimilating TEM-SPED orientation maps into a multiphase-field model using an ensemble Kalman filter, wherein simulation parameters were iteratively updated to reproduce the experimental observations. The same field of view in a 50% cold-rolled pure-aluminum foil was repeatedly observed by TEM-SPED after successive ex situ isothermal annealing at 400 °C for up to 20 min at 5 min intervals. Through the assimilation process, grain boundary mobilities that reproduced the experimentally observed microstructural evolution were identified. A simulation restarted from the initial microstructure using the inferred mobilities achieved approximately 91% agreement with the experimental observations, suggesting that the inferred mobilities were suitable for predicting the observed microstructural evolution. These results demonstrate that the direct assimilation of nanoscale TEM-SPED observations improves the prediction of complex local grain boundary migration and enables the estimation of effective grain boundary mobilities.

Journal of Manufacturing and Materials Processing doi: 10.3390/jmmp10100405

Authors: Stefan Donaubauer Johannes Eppinger Stefan Weihe Martin Werz

Friction stir welding of T- and corner-joint configurations is challenging due to restricted tool accessibility, complex material flow and the limited availability of material for the formation of load-bearing fillet-weld geometries. This study introduces wire-based corner fillet friction stir welding (W-CFFSW), a solid-state joining process in which filler wire is continuously transported, plasticised and supplied into the internal corner region through a rotating extrusion screw. A stationary shoulder confines and shapes the deposited material, enabling the formation of fillet welds with a defined throat thickness. Single- and double-sided fillet-weld geometries were produced in 3.0 mm thick EN AW-6082-T6 sheets using EN AW-6082 filler wire. A throat thickness of 4.5 mm was successfully generated by adapting the supplied filler volume to the targeted fillet geometry. Metallographic investigations revealed characteristic FSW microstructural zones and pronounced material flow within the weld nugget zone, while no macroscopic pores or voids were observed in the investigated cross-sections. The hardness distribution exhibited the characteristic W-shaped profile of precipitation-hardenable aluminium alloys. Bending tests showed no separation of the bonding interfaces, with cracking occurring in the adjacent sheet material rather than within the fillet welds. Tensile strengths of 231.55 MPa and 217.49 MPa were achieved for stiffener- and stringer-loaded specimens, corresponding to joint efficiencies of 66 % and 62 %, respectively. The results demonstrate that W-CFFSW enables the controlled addition of filler material to produce mechanically load-bearing fillet welds with a defined throat thickness and represents a promising alternative to existing friction-stir-based T- and corner-joint processes.

Journal of Manufacturing and Materials Processing doi: 10.3390/jmmp10100404

Authors: Alec C. Pfundheller Yinyin Hong Benjamin E. Mejia Diaz Michenna Allen Zhihan Hu Sisi Xiang Shannon C. Orsak Dan J. Thoma Lin Shao

Additively manufactured (AM) 316L stainless steel fabricated by laser powder bed fusion was irradiated with 5 MeV Fe self-ions to 50 peak displacements per atom at 600 °C to evaluate its swelling resistance in reactor-relevant environments. Cross-sectional transmission electron microscopy (TEM) revealed large voids with diameters up to 140 nm that were preferentially aligned rather than randomly distributed. The spacing between adjacent void strings was approximately 500 nm, matching the cellular wall structure present prior to irradiation. It is hypothesized that the high dislocation density associated with these walls acts as a strong yet biased sink for interstitials, promoting local vacancy accumulation and enhanced void formation. This facilitated nucleation also reduces the influence of injected interstitials, resulting in a wider safe analysis zone than typically observed during heavy-ion irradiation. Swelling measurements extracted from this region show an approximately linear dependence on local damage level, corresponding to a swelling rate of ~1% per dpa with little or no incubation period. The results indicate that the cellular structures play an important role in void swelling. The results demonstrate that the retained cellular structure plays a dominant role in void swelling evolution in AM 316L stainless steel. Therefore, post-build stress-relief treatments should be carefully optimized to reduce cellular dislocation density and enhance the swelling resistance of AM 316L for nuclear reactor applications.

Journal of Manufacturing and Materials Processing doi: 10.3390/jmmp10100403

Authors: Mehdi Moayyedian Mohsen Hedayati-Dezfooli Mohamed Fayed Askhat Mussin Vuk Cvorovic Ibrahim Elbadawy

This study systematically investigates and optimizes the influence of Fused Deposition Modeling (FDM) process parameters on the macroscopic tensile strength of polylactic acid (PLA) components. Addressing the need for predictable structural performance in 3D-printed parts, the novelty of this work lies in establishing a holistic, multi-stage optimization framework that maps the combined kinematic and geometric interactions of critical printing parameters directly to structural failure mechanisms and microstructural integrity. A systematic four-phase methodology was executed using a Taguchi L25 orthogonal experimental design to evaluate four manufacturing variables, namely layer thickness (P1), infill percentage (P2), nozzle retraction speed (P3), and nozzle travel speed (P4) across five discrete levels. Uniaxial destructive tensile testing on an ST Series Universal Testing System revealed that the initial ultimate tensile strength spanned a broad range from 20.04 MPa to a peak of 32.59 MPa. Signal-to-noise (S/N) ratio analysis (“Larger-the-Better”) and Analysis of Variance (ANOVA) at a 95% confidence level established layer thickness (P1) as the strictly dominant governing factor (F = 5.56), contributing 43.14% to total system variance. Parametric impact tracking confirmed secondary physical contributions from retraction speed (P3, 20.86%) and infill percentage (P2, 16.82%), while nozzle travel speed (P4, 3.90%) exhibited a negligible effect. Experimental confirmation testing using the identified optimal combination (0.20 mm layer thickness, 90% infill, 40 mm/s retraction speed, and 80 mm/s travel speed) yielded a peak ultimate tensile strength of 36.6 MPa, achieving a 12.3% improvement over the initial experimental maximum. Ultimately, this research offers a highly predictable, mathematically validated manufacturing strategy for converting empirical FDM adjustments into reliable and solid engineering components.

Journal of Manufacturing and Materials Processing doi: 10.3390/jmmp10100402

Authors: Mohsen Ghajar Seyed Mohammad Reza Khalili Seyed Mohammad Hashemi

This research establishes critical process–property relationships for the Fused Deposition Modeling (FDM) of rigid (PLA) and functional flexible (TPU) polymers. By systematically evaluating the influence of key manufacturing parameters—infill density, print orientation, and loading rate—this study quantifies the structural integrity and operational limits of 3D-printed components. Tensile characterization, conducted according to ASTM D638-14 standards, reveals that horizontal and laid manufacturing strategies produce superior mechanical properties, whereas vertical configurations exhibit significant anisotropy due to interlayer bonding constraints. Stress–strain analysis differentiates the brittle, high-stiffness response of PLA from the hyper-elastic and viscoelastic behavior of TPU, highlighting the latter’s sensitivity to rate-dependent processing. A critical finding for advanced manufacturing is the role of support-induced interfaces: while negligible for rigid PLA, support structures are shown to be detrimental to TPU, reducing maximum elongation by over 70% and necessitating support-free design strategies for functional elastomeric parts. Higher infill densities consistently enhance structural performance, providing a clear roadmap for optimizing material efficiency. These findings provide a principled framework for Design-for-Manufacturing (DfM) optimization, enabling the reliable production of tailored components for aerospace, biomedical, and soft-robotic applications.

Journal of Manufacturing and Materials Processing doi: 10.3390/jmmp10100401

Authors: Ashith Ajithan Hessam Ghasemnejad Sompong Srimanosaowapak

The automotive industry prioritises passive safety, emphasising the development of safer cars through sustainable designs rather than performance alone. The objective of this study is to investigate the development and implementation of waste-filled portable crash boxes to improve the crashworthiness performance of road service vehicles using sustainable materials such as beverage cans. Experimental studies were conducted to determine material properties; consequently, quasi-static and impact tests were performed to evaluate the crashworthiness performance of sustainable absorbers. Various finite element models were developed in LS-DYNA to assess the crashworthiness of structures, enabling the identification of potential improvements to crash components for road safety vehicles under real-world conditions. The outcomes of this investigation aim to demonstrate the feasibility of repurposing recycled aluminium beverage cans as sustainable, low-cost, and efficient energy absorbers to enhance road safety and vehicle crash protection. Finally, the crashworthiness parameters, such as specific energy absorption (SEA) and mean crush force (Fm), are compared between experimental and numerical results with errors of less than 10%.

Journal of Manufacturing and Materials Processing doi: 10.3390/jmmp10100400

Authors: Shahriar Imani Shahabad Ali Bonakdar Ehsan Toyserkani

The laser powder-bed fusion (LPBF) process frequently encounters issues such as residual stresses and part deformation, primarily due to the steep temperature gradients that occur during fabrication. Relying on experimental trial-and-error methods to address these issues is time-consuming and inefficient. As an alternative, numerical modeling and simulation can provide accurate predictions of residual stresses and deformation. However, traditional large-scale thermo-mechanical simulations for LPBF are computationally expensive. This study presents a novel model that utilizes an effective heat input to accelerate LPBF process simulation. The model is applied to cube and cantilever geometries under varying process parameters to predict residual stresses and deformation. Experimental validation is performed using X-ray residual stress analysis and optical scanning. Results show that using an effective heat source significantly reduces computation time while maintaining prediction accuracy.

Journal of Manufacturing and Materials Processing doi: 10.3390/jmmp10100399

Authors: P. Garcia Garcia Gil I. Brandherm M. Heil D. Savran C. Caesar J. Weinert S. Schwab T. Aumann E. Casarejos C. J. Schmidt H. Simon A. Zilges

High-Energy and Nuclear Physics research facilities around the world demand cutting-edge instruments dedicated to exploring the signatures of particles knocked out by collisions at ultra-relativistic energies. Each instrument is a class of its own, but shares underlying technologies proven to solve specific challenges. Polymer-based scintillating fibers (cross sections typically below 1 mm2) are sensitive to a large range of particle types and broad energy ranges and provide a fast response, fine spatial segmentation, and a low material budget, making them suitable for particle tracking, beam monitoring, and timing applications. Indeed, scintillating fibers can cover a large variety of shapes and sizes when assembled as ribbons, also allowing for multilayer designs. While most multilayer fiber detectors employ round-section fibers in staggered layers configuration, the square cross section permits regular arrangements with gapless fully packed ribbons and a quasi-uniform distribution of sensitive material. This work presents the manufacturing process developed at the Detector Laboratory of GSI Helmholtzzentrum für Schwerionenforschung (Germany) for manufacturing single- and multilayer ribbons made of scintillating square fibers. The complete production sequence is described, including fiber winding and positioning, bonding of layers, stacking and alignment of multilayer ribbons, integration of mechanical interfaces, machining and surface finishing of the optical couplings, and quality control procedures. Dedicated tooling was developed for each production stage to provide mechanical reproducibility and scalability. The process can be fully adapted to different fiber sizes, ribbon widths and lengths, and layer configurations, enabling the production of both small prototypes and large-format modules. This technology, already validated in operative instruments, is being deployed in a new generation of experiments for the international Facility for Antiproton and Ion Research (FAIR) research center.

Journal of Manufacturing and Materials Processing doi: 10.3390/jmmp10100398

Authors: Muhammad Abdullah Syed Masood Arif Bukhari Naveed Husnain Muhammad Sultan Sohaib Tahir Chauhdary Qi Wang Muhammad Tuoqeer Anwar Hassan Raza Mustabshirha Gul Muhammad Farhan Hanif Farrukh Arsalan Siddiqui Masooma Amjad Khokhar

Since the late 1980s, additive manufacturing (AM) has emerged as a prominent fabrication technology, experiencing significant advancements over the past decades. Even with its rapid development, this technology still faces many manufacturing challenges. Driven by the development of AM, 5D printing evolved from conventional 3D printing by incorporating five controlled degrees of freedom (three translational and two rotational axes) to enable non-planar deposition, curved-layer fabrication, and improved control of deposition orientation. This review critically analyses and summarizes 5D printing technology, detailing its development, material innovations, applications, and future outlook. The study starts with the evolution of printing from 1D printing, through 2D printing, to 3D printing, detailing its limitations and the paradigm shift to 5D printing. Further insights are also discussed regarding material selection, which plays a crucial role in determining the functionality and performance of 5D printing. Moreover, various applications of 5D printing across the aerospace, automotive, biomedical, jewelry, and food industries have been discussed, highlighting its potential for lightweight, high-strength, and tailored components. Furthermore, a detailed SWOT analysis of 5D printing has been presented to evaluate the strength, weaknesses, opportunities and threats of the technology, providing a strategic perspective of 5D printing in the industry. Lastly, future prospects for multi-material integration, AI-optimized printing and hybrid manufacturing methods are discussed.

Journal of Manufacturing and Materials Processing doi: 10.3390/jmmp10100397

Authors: Delong Zhao Heyu Zhang Zijie Huang Ke Xu

Surface inspection in continuous steel-pipe production is increasingly expected to provide timely and traceable quality information for downstream review and disposition, rather than only identifying visible defects. This requirement becomes challenging when changes in pipe specification simultaneously alter point-cloud scale and cylindrical surface geometry, while surface disturbances, processing-time constraints, and asymmetric field costs further affect inspection decisions. To address these coupled issues, this study develops a traceable 3D inspection framework that connects point-cloud organization, defect-sensitive representation, and production-oriented detector calibration. Source-index-preserving regularization first converts variable-size point clouds into a unified representation while retaining access to the original data. A multi-scale residual projection method is then introduced to suppress cylindrical trends and slowly varying surface undulation while preserving local geometric deviations for efficient detection. For deployment, class-specific confidence thresholds, selective 3D candidate review, and overlap-graph consolidation are jointly calibrated according to production priorities related to missed defects, review workload, and computational cost. Experiments using data acquired from an actual steel-pipe production environment show that the proposed method improves defect-sensitive representation while maintaining a P95 front-end latency of 83.62 ms. The calibrated workload-balanced profile further increases defect recall from 87.28% to 92.76% compared with the regular best model. The results demonstrate that source data and production requirements can be incorporated into a unified inspection chain, providing a practical route for adapting general vision detectors to variable-specification, continuously operated industrial inspection.

Journal of Manufacturing and Materials Processing doi: 10.3390/jmmp10100396

Authors: Mohd Kaswandee Razali Suk Hwan Chung Man Soo Joun

Control of carbide morphology during heat treatment plays a decisive role in achieving stable dimensions, improved cutting performance, and reliable mechanical properties in precision steel components. In this work, a computational approach is developed to analyze the spheroidization behavior of cementite in eutectoid Fe-0.8 wt.% C steel subjected to cyclic thermal processing. The model, implemented within a finite element method (FEM) framework, links the transient local temperature history to temperature-dependent spheroidization kinetics. The kinetic formulation is physically motivated by established mechanisms of cementite spheroidization, including carbon diffusion and curvature-driven reduction of interfacial energy; however, carbon concentration and interface curvature are not explicitly solved as independent FEM field variables. Instead of relying on empirical correlations, the transformation kinetics are described through physically based rate equations that account for temperature dependence and accumulated thermal exposure. A morphology evolution parameter is introduced to quantitatively represent the transition from lamellar pearlite to spheroidal carbide particles during repeated heating cycles. Numerical predictions indicate that cyclic reheating enhances the transformation rate due to progressive lamella fragmentation and increased interfacial stability, leading to accelerated approach toward equilibrium morphology. The simulated evolution trends are consistent with reported experimental behavior, confirming the validity of the modeling strategy. This study demonstrates the feasibility of integrating microstructural kinetics into process simulation platforms, providing a practical tool for optimizing heat-treatment schedules in precision manufacturing applications while minimizing experimental iterations.

Journal of Manufacturing and Materials Processing doi: 10.3390/jmmp10100393

Authors: Andrey A. Aksenov Ilya V. Bardin Vitali V. Doroshenko Darya M. Strekalina Vasily O. Tomshin Tatiana D. Lubimova Ivan V. Shkalei Olga A. Yakovtseva

Coatings with thicknesses of 25, 50, and 100 μm were formed in an alkaline-silicate electrolyte at a constant anodic current density of 10 A/dm2 in the Soft-mode. A multi-technique approach, including SEM-EDX, XRD, EIS, and microhardness testing, was employed to characterize the coatings. The coatings with thicknesses of 50 and 100 μm consisted of three layers: a base layer, a pancake layer, and an outer porous layer. The outer layer of the coating is enriched in silicon (from electrolytes) and alloying elements of the substrate, due to the occurrence of micro-arc discharges, type-B discharges, which eject plasma containing these elements into the surface layers of the coating. Phase analysis reveals a progressive increase in the α-Al2O3 modification with an increase in coating thickness, which correlates with enhanced microhardness. Electrochemical testing in a 3% NaCl solution demonstrates that the 100 μm Soft-mode coating provides the highest corrosion protection, significantly outperforming both thinner coatings and Arc-mode counterparts. In the Soft-mode, small “external” discharges organize into moving groups, enabling uniform thickness build-up. A model of these discharges is proposed, interpreting them as “type B discharge light” that does not reach the surface due to the presence on the surface of the “pancake-like” layer formed by type-B discharges of a hydrogen-saturated porous outer layer.

Journal of Manufacturing and Materials Processing doi: 10.3390/jmmp10100395

Authors: Ji Zhang Weijian Zhang Yunfeng Jia Ruiguang Chen Rongpei Shi Boxuan Cao Suzhu Yu Xiangli Liu Jun Wei

Laser powder bed fusion (L-PBF) of near-β titanium alloys typically produces coarse columnar grains and strong <001> textures, which induce anisotropic mechanical behavior. Here, 5 wt.% tantalum (Ta) particles were doped into Ti-5Al-5Mo-5V-3Cr (Ti-5553) powder to concurrently inhibit microstructural anisotropy and contribute to enhanced strength–ductility synergy via solidification modification. During the L-PBF process, unmelted Ta particles provided heterogeneous nucleation sites, while dissolved Ta generated local constitutional undercooling. Together, these effects reduced the average β-grain size from 47.23 ± 27.5 to 12.28 ± 11.8 μm and weakened the <001> texture, as well as increased yield strength from 870 to 990 MPa while retaining 28% elongation. After solution treatment and aging, Ti-5553-Ta reached a yield strength of 1196 MPa and 16.0% elongation. Local Ta-enriched precipitate-free zones and refined α precipitates contributed to the improved post-treatment ductility.

Journal of Manufacturing and Materials Processing doi: 10.3390/jmmp10100394

Authors: Han Wang Xiutao Tang Rui Ma Shouzhen Zhou Hao Chang Chengkun Li Fang Han Zhihang Zhang Chengcheng Wang Xiaoqing Zhu Zhibo Dong

Low-angle overhang structures in laser powder bed fusion (LPBF) experience strongly geometry-dependent thermal conditions because the underlying material progressively changes from consolidated solid to low-conductivity powder, which raises a fundamental question regarding the conventional use of a uniform inherent strain for efficient residual stress and distortion prediction. In this study, the dynamic inherent strain (DIS) method is employed to investigate the inherent strain behavior of LPBF overhang structures with different tilt-angles. The results reveal that after excluding the boundary-affected stages of the build, the representative inherent strain exhibits a systematic dependence on tilt-angle in both magnitude and tensor characteristics. Based on this angle dependence, compact angle-dependent expressions are established using trigonometric basis functions for engineering implementation. Comparisons with residual stress measurements at the experimentally investigated 30° and 90° geometries further indicate that angle-specific inherent strain assignment has a greater influence on the mechanical response toward the lower bound of the investigated angular range.

Journal of Manufacturing and Materials Processing doi: 10.3390/jmmp10100392

Authors: Alessandro Pellegrini Maria Grazia Guerra Riccardo Cristiani Fulvio Lavecchia

Material Extrusion of metals (MEX/M) followed by debinding and sintering is a cost-effective multi-step route for producing complex metallic components. However, the inherent staircase effect and sintering-induced distortions often necessitate aggressive post-treatment processes to meet industrial requirements. The aim of this study is to investigate the effect of multi-stage surface mechanical treatment on a comprehensive benchmark sample containing diverse geometric primitives such as overhang prismatic features, cylinders, holes, pyramids, etc. A 3D structured light scanner was adopted to evaluate the evolution of dimensional accuracy and geometrical characteristics. The results indicate that sequential treatment effectively mitigates the layer-by-layer deposition. However, this effect carried an improvement in circular features such as cylinders or hollow rings, while for prismatic features such as prisms or pyramids it caused a measurable edge roll-off effect, highlighting a critical trade-off between smoothness and sharp-feature retention. Dimensional analysis reveals strong orientation-dependent shrinkage behavior during sintering, which is further modified by the material removal rates of the surface mechanical treatment stages. This work provides a qualitative and quantitative analysis of the final geometrical limits of the MEX/M technology cycle and offers insights into optimizing surface post-treatment parameters for high-performance applications.

Journal of Manufacturing and Materials Processing doi: 10.3390/jmmp10100391

Authors: Suyash Niraula Brendon S. Dodge Justin D. Gillham Thomas A. Berfield

This study presents a detailed microanalysis and microstructural characterization of the multi-material 316L–IN718 system produced in a prior work by the powder binning method for Laser Powder Bed Fusion (L-PBF), in which these multi-material samples were fabricated in a single build and then mechanically tested. This effort extends the investigation by applying X-ray micro-computed tomography (Micro-CT), electron backscatter diffraction (EBSD), energy-dispersive X-ray spectroscopy (EDS), and X-ray diffraction (XRD) techniques to specimens produced under the baseline single-scan condition to examine the interface transition in volumetric porosity, crystallographic structure, and elemental composition. Micro-CT analysis revealed that the interface region exhibited the highest void volume ratio among the three analyzed regions, reaching 0.91%, compared to 0.32% for 316L and 0.37% for IN718. The interface also contained the largest defects, including the only voids with volumes exceeding 500,000 µm3, indicating that critical flaws, while not widespread, were concentrated at the dissimilar material boundary. EDS line scanning across four locations along the interface confirmed a diffuse compositional transition that closely and consistently supports the interface width independently reported via microhardness for the same material pairing in the original study. EBSD mapping showed a gradual grain structure transition with coarser equiaxed grains on the 316L side, and the entire scan indexed successfully with a single face-centered cubic structure file, with no secondary or intermetallic phases detected at the resolution of the measurement. Collectively, these results explain the failure behavior reported previously: the compositionally strengthened, defect-rich interface sheds plastic strain into the adjacent, softer 316L, which fails first due to its lower strength and coarser void population. Under monotonic tensile loading, improving binning-based multi-material performance therefore depends primarily on strengthening or targeting defect-reduction strategies at the weaker 316L constituent.

Journal of Manufacturing and Materials Processing doi: 10.3390/jmmp10100389

Authors: Yashar Javadi

Residual stress influences dimensional stability, fatigue, fracture and structural integrity in welded and additively manufactured components. Ultrasonic methods offer a non-destructive and deployable alternative to diffraction and strain-relief techniques because stress changes elastic-wave velocity through acoustoelasticity. This review traces ultrasonic residual stress measurement from nonlinear elasticity and single-element longitudinal critically refracted (LCR) waves to finite-element-assisted LCR, robotic phased-array inspection and Phased-Array Ultrasonics for Residual Stress Measurement (PAURS). It critically examines time-of-flight precision, depth and path averaging, reference-state uncertainty, temperature, coupling, geometry, Type I residual stress and its interaction with phase transformation, microstructure and texture. PAURS improves multi-path redundancy and diagnostic capability, while quantitative accuracy remains dependent on calibration and material-state effects. PAURS+ is proposed as the convergence of PAURS with phased-array microstructure characterisation; unlike experimentally demonstrated PAURS, it remains a conceptual multi-observable framework requiring quantitative validation. The review concludes that integrated in-process material-state measurement requires PAURS+ for multi-observable sensing, robotic high-temperature inspection for deployment, and coupled process, material and wave models for interpretation. Physics-informed AI, independent ground truth, uncertainty assessment and digital-twin updating are required to connect these capabilities to traceable manufacturing decisions.

Journal of Manufacturing and Materials Processing doi: 10.3390/jmmp10100390

Authors: Alexey Markov Evgeniy Yakovlev Evgeniy Pesterev Andrey Solovyov Vsevolod Petrov Massimiliano Bestetti Alexandr Shmakov

The results are presented for an in situ synchrotron investigation of phase composition evolution during surface alloy synthesis. Surface alloys 3–5 µm thick are synthesized using pulsed melting with a microsecond low-energy, high-current electron beam. Three bilayer systems are studied: Ti(1000)/Zr, Y(1000)/Zr, and Mo(1000)/Zr, representing (1) alloys forming continuous solid solutions, (2) alloys with limited solubility and (3) alloys forming intermetallic compounds, respectively. In the first case, a surface alloy forms through the continuous solution of Ti in α-Zr as a homogeneous equilibrium substitutional solid solution with an average Ti concentration of 40 at.%. In the second case, gradual dissolution of Y in α-Zr forms an inhomogeneous metastable oversaturated solution with average and surface Y concentrations of 18 and 32 at.%, respectively. In the third case, an inhomogeneous metastable surface alloy forms, consisting of α- and β-Zr phases, with the latter predominating. The average and surface Mo concentrations are 30 and 42 at.%, respectively. Prior to the formation of β-Zr with a high Mo content, a nonequilibrium unidentified phase appears that could be referred to as a high-concentration solid solution of crystalline Mo with Zr embedded in it from the melt.

Journal of Manufacturing and Materials Processing doi: 10.3390/jmmp10100388

Authors: Jianhua Yin Shihao Liu Zhijun Zheng Zhongchen Lu

Extrusion is a core branch of advanced metal forming. Over the past century, it has evolved from conventional hot and cold extrusion into a diversified family of processes that now encompasses severe plastic deformation (SPD) techniques. The industrial limits of these processes are governed by a small set of dominant physical mechanisms: dynamic recrystallization (DRX), which dictates grain refinement; adiabatic heating and the associated hot shortness (surface cracking), which bound the maximum usable extrusion speed; and, in porthole-die and hybrid extrusion, the pressure-temperature-time criteria that govern solid-state seam-weld integrity. This review examines metal extrusion and the closely related SPD technologies from this mechanism-oriented perspective. First, it elucidates the fundamentals governing metal flow and deformation behavior (MFDB) during extrusion, including the primary shear zone, the dead metal zone, and container-wall friction, together with the influence of material-intrinsic factors (alloy composition and initial grain morphology) and external conditions (die design and process parameters). Second, it discusses the key role of die design and manufacturing in regulating metal flow and ensuring product precision, including the application of finite element analysis (FEA) and intelligent algorithms to die optimization. The core of this review is a comparative analysis of state-of-the-art processes, organized into two kinematically distinct categories: continuous profile-forming extrusion, in which the billet is forced through a die orifice (direct, indirect, lateral, field-assisted and shear-assisted variants), and discrete SPD-based conditioning, in which large strains are accumulated at constant cross-section, covering cyclic extrusion compression (CEC), high-pressure torsion (HPT), equal-channel angular extrusion (ECAE), field-assisted extrusion (FAE), and shear-assisted processing and extrusion (ShAPE). For each technology, the working principle, die structural features, and distinctive effects on microstructural evolution (grain refinement, phase transformation, texture regulation) and mechanical properties (strength, ductility, wear resistance) are detailed. Finally, current industrial applications are summarized, and future development trends are outlined, including intelligent monitoring systems, modular equipment, and hybridization with additive manufacturing, with the aim of achieving green and efficient forming of metallic materials.

Journal of Manufacturing and Materials Processing doi: 10.3390/jmmp10100387

Authors: Ping Zhang Shuai Ge Jie Gao Hui Yang Youqiang Wang

A three-dimensional coupled finite element model incorporating the cutting tool, workpiece, and simulated impact pin was developed using ABAQUS/Explicit to investigate the machining behavior of Inconel 718 under conventional cutting and ultrasonic impact-assisted cutting conditions. Three ultrasonic impact trajectory spacings of 2, 3, and 4 mm were considered, where the trajectory spacing denotes the transverse distance between the centerlines of adjacent ultrasonic impact trajectories. Single-factor analyses were conducted by varying the cutting speed, depth of cut, and tool rake angle. The investigated cutting speeds ranged from 400 to 2000 mm/min, the depths of cut from 0.09 to 0.21 mm, and the tool angle from 10° to 30°. Experiments were performed using a KZUIT-20C ultrasonic system operating at 20 kHz with a 4 mm diameter impact head and a Mitsubishi MV820 CNC machine tool equipped with a titanium-alloy cutting tool. The numerical model was established based on the Johnson–Cook constitutive model and validated against experimentally measured cutting forces, with a maximum relative error of 11.23%. The results show that the ultrasonic impact trajectory spacing has a pronounced influence on the subsequent cutting-force response of Inconel 718. With increasing cutting speed, the X-direction cutting force generally increases under all investigated conditions, whereas the Y-direction force exhibits a more condition-dependent response. At a cutting speed of 2000 mm/min, the X-direction cutting forces under conventional cutting and 2, 3, and 4 mm trajectory spacings are 53.48, 56.38, 56.45, and 40.49 N, respectively. The 4 mm spacing consistently produces the lowest X- and Y-direction cutting forces over the investigated cutting-speed range. As the depth of cut increases, the X-direction cutting force generally increases, particularly at larger cutting depths, while the 4 mm condition maintains a comparatively low and smooth force response. The Y-direction cutting force shows stronger fluctuations depending on the trajectory spacing and cutting depth. Variation in tool angle produces relatively moderate changes in the X-direction force, whereas the Y-direction force exhibits a more pronounced condition-dependent response, including a localized increase under the 3 mm spacing condition. The residual stress and tool-temperature responses further demonstrate that the spatial distribution of ultrasonic impact trajectories affects the subsequent thermomechanical behavior of the machined material. Within the investigated parameter range, the 4 mm trajectory spacing generally maintains relatively low cutting-force levels and a comparatively stable thermal response. These results suggest that an appropriate separation between adjacent impact trajectories can reduce excessive interaction between neighboring impact-affected regions and thereby modify the mechanical resistance encountered during subsequent material removal. The present findings provide a numerical and experimental basis for selecting suitable ultrasonic impact trajectory spacing and machining parameters for the high-performance machining of Inconel 718.

Journal of Manufacturing and Materials Processing doi: 10.3390/jmmp10100386

Authors: Natalia Menshutina Andrey Abramov Yan Sulkhanov Victoria Zharlikova Roman Akasov Ekaterina Volina

Additive manufacturing makes it possible to create objects with complex geometry for various applications, including personalized implants. Hydrogel scaffolds with shape-morphing effects are of particular interest in the field of soft tissue engineering. This work describes the technology of extrusion-based 3D printing of objects of complex spatial shape based on biopolymer viscous ink. A technique for producing viscous ink based on sodium alginate, hydroxypropylmethylcellulose and silver nanoparticles embedded in a polymer matrix has been developed. The sizes of silver nanoparticles were determined via dynamic light scattering. The colloidal stability of silver nanoparticles was assessed by analyzing the peak of surface plasmon resonance using UV-VIS spectroscopy. The compliance of the developed viscous ink with the requirements for materials for extrusion-based 3D printing was confirmed by the results of comprehensive rheological research. The main patterns of the relationship between the infill pattern parameters during 3D printing and the degree of deformation of hydrogel structures resulting from anisotropic swelling of sections of various thicknesses have been identified. The developed Alg3/HPMC3/AgNPs scaffolds exhibited preliminary cytocompatibility and supported cell viability. The deformation of hydrogel structures was modeled using finite element analysis, which enables the prediction of their spatial shape for further design of personalized cartilage implants.

Journal of Manufacturing and Materials Processing doi: 10.3390/jmmp10100385

Authors: Mohammad Lotfalian Graziano Chila Sivakumar Narayanswamy

This study investigates the process control and improvement in the repeatability of UV nanosecond laser ablation of polyamide-coated platinum micro-wires while preserving post-ablation mechanical integrity. For this purpose, a jig was developed to control wire positioning, alignment, focal distance, rotation, and immersion depth during water-assisted laser processing. Selected ablation conditions were repeated and compared with corresponding results from previous work, while additional uncoiled and unablated specimens were included to examine the influence of prior wire condition and provide a mechanical reference. Surface quality was evaluated using microimaging and surface roughness measurements, and mechanical response was assessed through pull-to-rupture testing. The surface results showed that the selected processing conditions produced different levels of roughness and surface uniformity, while the mechanical results showed improved consistency in the jig-assisted trials compared with the previous datasets. The comparison also indicated that prior wire handling and mechanical history can influence rupture behavior independently of the laser process. Overall, the results support the use of controlled mechanical referencing as an effective approach for improving repeatability in water-assisted laser coating removal.

Journal of Manufacturing and Materials Processing doi: 10.3390/jmmp10100384

Authors: Guihua Liu Yuchao Wu Shineng Peng Qingjie Liu

A reconfigurable, flexible, and modular fixture system is proposed for the milling of irregular thin-walled parts, which are commonly encountered in aerospace applications and require high machining precision. Conventional universal fixtures often fail to provide adequate support for such components, particularly in terms of clamping stress, operational efficiency, and vibration control, while dedicated fixtures tend to be costly. The developed design, guided by the Theory of Inventive Problem Solving (TRIZ), incorporates six independently adjustable jaws. These jaws can be reconfigured according to the part geometry, enabling flexible adaptation to different workpiece shapes. Through a pre-processing step applied to the jaw surfaces, the fixture achieves area-based contact with the part, replacing the line-contact mode typical of conventional setups. This improves clamping stability, reduces localized stress, and mitigates vibration during machining, thereby contributing to improved accuracy. In addition, once the jaw positions are determined based on a trial cut of the initial workpiece, they remain fixed for subsequent parts, streamlining the setup process. Machining trials showed that surface-contact clamping reduced roundness tolerance from 0.0523 mm to 0.0287 mm, flatness from 0.0106 mm to 0.0036 mm, and parallelism from 0.0190 mm to 0.0105 mm. The resulting fixture offers a combination of structural simplicity, adaptability, cost-effectiveness, and machining reliability, making it suitable for thin-walled components in small-batch or varied production contexts.

Journal of Manufacturing and Materials Processing doi: 10.3390/jmmp10100383

Authors: Pavan Hiremath R. C. Shivamurthy Manjunath Shetty Satisha Prabhu Terence Xiaoteng Liu P. Krishnananda Rao

Gas carburization is widely used to improve the surface durability of load-bearing steels, yet alloy-dependent thermodynamic and kinetic effects often cause large variability in case development and component life. This study presents a physics-guided comparison of carburization behavior in EN3, 20MnCr5, and EN353 steels by integrating hardness profiles, mechanical and wear testing, and thermodynamic–diffusion analysis. Under an identical boost–diffuse–equalize cycle at 930 °C, distinct surface carbon levels of 0.764 wt.% (EN3), 0.792 wt.% (20MnCr5), and 0.822 wt.% (EN353) were obtained. These corresponded to effective case depths of ~1 mm in EN3 and ~2 mm in 20MnCr5 and EN353. Near-surface hardness reached ~12–13 HRC in EN3, ~33 HRC in 20MnCr5, and ~35–36 HRC in EN353. Ultimate tensile strength increased from ~620 MPa (EN3) to ~870 MPa (EN353), while wear mass loss decreased from ~28 mg to ~21 mg. Thermodynamic interpretation showed alloy-dependent moderation of carbon activity and sustained chemical-potential gradients, promoting deeper diffusion. Reconstructed carbon profiles confirmed diffusion-controlled case growth. By enabling longer service life and reduced material replacement, the results support durability-oriented and resource-efficient surface engineering for engineering steels.

Journal of Manufacturing and Materials Processing doi: 10.3390/jmmp10100382

Authors: Ping Zhang Zhimin Zhao Jie Gao Junbao Zhang

This study investigates the micro-cutting mechanism of a 7A09 aluminum matrix composite reinforced with CoCrFeNiAlX (referred to as AlX) high-entropy alloy particles, chosen for their superior wetting properties with aluminum. Using simulation analysis, the research explores how high-entropy alloy particles with varying aluminum content influence the micro-cutting behavior of the aluminum-based composite. The results indicate that cutting force is minimized when the cutting path is above the particle and maximized when below, with a difference of approximately 201 N. Cutting force increases with cutting speed, but the rate of change varies significantly across speeds, with a maximum increase of 67%. The highest cutting temperatures, at 301 °C and 304 °C, are observed when cutting depth and speed are maximized, respectively, with temperature more strongly influenced by cutting speed, leading to a temperature variation of up to 148 °C across different speeds. For composites with different aluminum contents, cutting temperatures follow the order Al1 > Al0.6 > Al0. When the cutting path passes above the particle, thinner chips undergo multiple fractures due to tensile stress; as the path shifts downward, chip breakage frequency increases with cutting depth. At a constant cutting depth, low-speed cutting produces discontinuous chips, while higher speeds yield more continuous chips, achieving the most complete chip formation at 1500 m/min. The surface smoothness, qualitatively reflected by nodal displacement, ranks as follows: path b > path d > path c > path a > path e. This research provides valuable data to enhance machining performance for high-entropy alloy particle-reinforced aluminum matrix composites.

Journal of Manufacturing and Materials Processing doi: 10.3390/jmmp10100381

Authors: Shihui Tian Jingxu Han Jinyu Ma Han Wu Xiao Han Yan Yan Yi Zhang Ke Xu

Accurate and efficient detection of interfacial delamination in Cu/Al clad sheets is essential for evaluating bonding quality in multilayer metallic structures. This study proposes an electromagnetic acoustic transducer (EMAT)-based nonlinear frequency modulation (NLFM) resonance method for non-destructive delamination characterization of Cu/Al clad strips. A two-layer resonance frequency model was implemented and validated through theoretical analysis, finite element simulations, and EMAT experiments, showing good agreement among the three approaches. To overcome the long acquisition time associated with conventional frequency-sweep methods, an NLFM excitation waveform incorporating frequency-dependent pre-emphasis was proposed to achieve broadband excitation with an optimized energy distribution over the target resonance frequency range. Compared to linear frequency modulation (LFM), the proposed NLFM method provided enhanced resonance amplitudes, reduced out-of-band energy leakage, and improved signal-to-noise ratio (SNR). An NLFM-based B-scan inspection method was further developed for delamination detection using artificial T-slot defects in Cu/Al clad sheets. The proposed method successfully identified defects with widths of 1.5–9.5 mm through resonance frequency variations. The detected defect distributions showed good agreement with the actual defect dimensions, demonstrating the capability of NLFM resonance analysis for non-contact and high-sensitivity delamination detection in multilayer metallic structures.

Journal of Manufacturing and Materials Processing doi: 10.3390/jmmp10100380

Authors: Hai Chung Luong Trung Nguyen Hoanh Son Truong Van-Huong Tran Nguyen Binh Thuan Nguyen Trong Thanh

This study investigates the factors governing the distribution of surface roughness in the finish grinding of complex freeform bone plates using a single-layer electroplated CBN ball end wheel on Ti6Al4V alloy. Eight independent workpieces were machined under fixed process parameters, four in the as-machined condition and four heat treated to 41 HRC, with each group ground sequentially by a dedicated wheel. Roughness was measured at twenty-one locations with three repeated measurements per location, and radial wheel wear was monitored across eight cross sections throughout the grinding sequence, yielding 504 observations. The spatial distribution of roughness proved reproducible, with intraclass correlation coefficients of 0.852 and 0.768 for the two groups, and was preserved across both material conditions. Wheel wear exhibited a two-stage behaviour and reduced roughness by 5.53 nm per micrometre of cumulative wear, consistent with the levelling of grain protrusion heights during run in. Heat treatment reduced mean roughness by 91.8 nm, corresponding to 24.0 percent, while regions of larger radius of curvature exhibited roughness higher by up to 77.5 nm. The measured roughness exceeded the geometric scallop limit by a factor of 16 to 103, indicating that the governing mechanism resides in the abrasive grit regime rather than in toolpath kinematics within the range of conditions examined.

Journal of Manufacturing and Materials Processing doi: 10.3390/jmmp10100379

Authors: Mohammed Abdulridha Abbas Muhannad Ahmed Anwer Hammoodi Shaheed Al-Luhaibi Mohd Amri Lajis Ramin Hashemi

Biomaterials such as polylactic acid (PLA) are utilized in tissue engineering to produce bone scaffolds by 3D printing; to resemble and integrate with natural bone, the scaffolds need a precise pore structure. However, PLA scaffold surfaces show indenting behavior when loads are applied, indicating that they are hard. Based on this behavior, the D-Shore index is a direct dimensionless measure of surface hardness, compared with the Brinell test, which uses the ratio of applied load to the area of the spherical indentation. In addition, the D-Shore method lacks analytical tools, has measurement variance due to PLA rebound and creep during measurement, and is affected by printed lines in the surface layers; it also lacks a mathematical model. Therefore, the current study focuses on developing an empirical model for D-Shore hardness based on experimental data from the Brinell and D-Shore methods. At the same time, explicit finite element analysis (EFEA), as a preliminary step, can predict a feasible scaffold design that provides the best resistance to indentation on the printed surface. Design-wise, the efficient levels used for the scaffold samples were 100, 150, and 200 μm for pore size, and 0°/90° and −45°/45° for layer orientation, to predict and validate the Brinell number and experimentally determine the D-Shore. Accordingly, the analysis of variance reveals that the layer orientation is a dominant parameter, and the feasible level was 100 × 100 μm2, with −45°/45° for pore sizes and layer orientation, respectively; the best correlation factor was R2 = 0.995. Ultimately, this practical approach shows that the empirical model for D-Shore is a robust tool for computing the hardness based only on Brinell outputs and can estimate the hardness of biomaterials fabricated from PLA without extensive testing, helping identify the optimal path for bone scaffold design.

Journal of Manufacturing and Materials Processing doi: 10.3390/jmmp10100378

Authors: Sándor Fenyvesi Róbert Zsolt Keresztes

Wire Arc Additive Manufacturing (WAAM) based on Cold Metal Transfer (CMT) welding produces near-net-shape metallic components, but post-process machining remains essential for dimensional accuracy and surface quality. This study investigates the dry turning machinability of EN AW-5083 aluminium alloy parts produced by CMT-based WAAM, focusing on tool-holder temperature (Tth) as a relative thermal indicator and surface roughness. Tth was monitored with a K-type thermocouple embedded in the tool holder and an Arduino-based data acquisition unit, while surface roughness (Ra) was measured with a portable contact profilometer after each pass. Three machining parameters—cutting speed, feed rate, and depth of cut—were investigated using a Taguchi L18 orthogonal array, with significance assessed through S/N ratio analysis and ANOVA. Grey Relational Analysis (GRA) was applied for multi-response optimisation, benchmarked against published machinability data for wrought and WAAM-fabricated aluminium alloys. Surface roughness was governed predominantly by feed rate, while Tth was most strongly influenced by depth of cut. The combined Taguchi–GRA optimisation identified a parameter set minimising both responses simultaneously. Benchmarking against three literature sources showed that the surface roughness achieved for the investigated CMT-WAAM material falls within the range reported for wrought EN AW-5083 under comparable machining conditions. These findings provide practical guidance for post-process machining of WAAM-produced aluminium components in hybrid manufacturing chains.

Journal of Manufacturing and Materials Processing doi: 10.3390/jmmp10100377

Authors: Yan Lu Songsong Zhang Kaizhou Zhang Jinsong Xiong Yong Luo Yibo Li Yong Zhang

Thermoplastic fiber-metal hybrid structures have attracted increasing attention for lightweight structure applications owing to their high specific strength and damage tolerance. Al/CF/PEEK hybrid components are promising lightweight structures in which the aluminum alloy and CF/PEEK layers undergo coupled deformation during hot stamping. However, how the presence of the aluminum layer modifies the deformation behavior of CF/PEEK in hybrid component forming has not been systematically clarified, particularly regarding its influence on stress–strain response, wrinkling, and subsequent spring-back. This study investigates the deformation behavior of Al/CF/PEEK hybrid V-shaped components through comparative finite element analyses of monolithic aluminum, single-material CF/PEEK, and hybrid structures. The material flow and stress–strain responses of the aluminum and CF/PEEK layers are comparatively analyzed between the monolithic and hybrid configurations, followed by an examination of the wrinkling behavior of CF/PEEK and Al/CF/PEEK and the spring-back responses of monolithic aluminum and the hybrid structure. The results show that, during the hot-stamping stage, the hybrid structure exhibits an S-shaped deformation pattern similar to that of monolithic aluminum, while the aluminum layer constrains the bending and fiber-direction shear deformation of the CF/PEEK layers. This constraint reduces the bending amplitude and shear deformation of CF/PEEK and consequently mitigates wrinkle formation. During the subsequent cooling stage, the differences in the coefficients of thermal expansion, elastic modulus, and crystallization-induced shrinkage between aluminum and CF/PEEK result in different free contraction tendencies. Because the two layers remain mechanically coupled during cooling, this mismatch results in mutual constraint and stress redistribution, leading to a reverse S-shaped residual stress distribution. The resulting residual stress state partially counteracts the spring-back tendency and reduces the spring-back deformation of the hybrid component. These results clarify how aluminum–CF/PEEK interaction modifies the deformation and stress–strain states of the constituent layers and thereby affects wrinkling and spring-back in thermoplastic fiber-metal hybrid structures.

Journal of Manufacturing and Materials Processing doi: 10.3390/jmmp10100376

Authors: Dastan Buitkenov Bauyrzhan Rakhadilov Piotr Kowalewski Yernar Altayev Aiym Nabioldina Balym Alibekova

The aim of this work is to investigate the influence of high-velocity oxygen-fuel spraying (HVOF) process regimes on the microstructure, phase composition, and mechanical and tribological properties of 86WC–10Co–4Cr coatings on a 12Kh18N10T stainless steel substrate. The coatings were formed under three HVOF spraying regimes, differing in oxygen and fuel flow rates. The study included microstructure (SEM), elemental composition (EDS), phase composition (XRD) analysis, instrumental indentation, confocal laser profilometry, and tribological tests using the ball-on-disk scheme under dry friction conditions. It was found that all coatings are characterized by a dense structure, low areal porosity of about 1.4%, and a relatively uniform distribution of the main elements. X-ray phase analysis confirmed the predominance of WC with the formation of an insignificant amount of W2C due to limited decarburization. The instrumented indentation hardness (HIT) ranged from 13.03 to 13.56 GPa, and the elastic modulus ranged from 334.4 to 342.0 GPa. The maximum hardness was obtained for C1 (13.56 ± 0.58 GPa), and the maximum modulus was for C3 (342 ± 19.1 GPa). The Ra values ranged from 2.8 to 4.19 μm. Tribological tests revealed differences in the mean wear values among the spraying regimes; however, these differences were not statistically significant (p = 0.921). The results obtained can serve as an experimental basis for selecting promising HVOF processes for the hardening and restoration of components used in pumping, mining, and metallurgical equipment; their operational effectiveness must be further confirmed under actual industrial conditions.

Journal of Manufacturing and Materials Processing doi: 10.3390/jmmp10100375

Authors: Jiri Hajnys Quoc-Phu Ma Aneta Jansova Marek Pagac Jakub Mesicek Antonin Trefil

Additive Manufacturing (AM) has revolutionized modern production. However, its integration with conventional or subtractive manufacturing remains underexplored. Therefore, this study investigates the machinability of 316L stainless steel (SS) produced by rolling and Powder Bed Fusion Laser Beam (PBF-LB) technologies under dry turning. The metrics investigated include cutting force, vibration, surface roughness, cutting-zone temperature, tool wear, and tool durability. Under the same experimental conditions, the PBF-LB samples exhibited greater variation in machining responses than the rolled samples. Among the tested conditions, the PBF-LB sample machined at the highest feed was associated with the highest cutting force (1351 N), highest cutting-zone temperature (477 °C), and shortest tool durability (60 s). The largest measured tool damage (4.12 mm), however, was observed for a different PBF-LB sample machined at a lower feed, with possible contribution of sample-to-sample variations in material and surface condition to tool wear. Optical microscopy on this sample revealed scratch-like marks and severe edge damage, which may be attributed to sliding and abrasive interactions. The observed differences in behavior between PBF-LB and rolled samples should be interpreted cautiously as independent sample replication and direct characterization of the tested materials were not performed. Overall, the results do not establish definitive statistical effects of manufacturing route but provide experimental observations of dry-turning behavior under a predefined set of cutting conditions, identifying sample variability and material characterization as considerations for future studies.

Journal of Manufacturing and Materials Processing doi: 10.3390/jmmp10100374

Authors: Hyunjo Yoo Juyoung Kim Dongyeop Shin Sanghyeon Yoon Kunmo Koo Heesoo Lee

We investigated the effects of relative humidity (30–80%) and temperature (5–35 °C) on the flow characteristics and hydration behavior of CaO powder used for basic oxygen furnace injection. We measured the untapped and tapped densities, angle of repose, and particle-size distribution to analyze the flow characteristics. Furthermore, microstructural characterization and phase analysis were performed to study the hydration behavior. The packing characteristics changed and the flowability of the CaO powder decreased under high-relative-humidity conditions, whereas no noticeable changes were observed with variations in temperature. In particular, large agglomerated particles were observed at 80% relative humidity, and the Ca(OH)2 phase fraction reached 56.9% in the relative-humidity series. These results indicate that the decrease in CaO powder flowability under high-humidity conditions is associated with hydration-related microstructural changes and moisture-promoted interparticle agglomeration, in addition to changes in the overall hydration state.

Journal of Manufacturing and Materials Processing doi: 10.3390/jmmp10100373

Authors: Morteza Mehralitabar Firoozjah Hassan Moslemi Naeini Mohammad Mehdi Kasaei Mehdi Karimi Firouzjaei Behnam Abbaszadeh Lucas F. M. da Silva

Fracture is one of the most common defects that occur during the roll forming process. However, several process-based strategies can be employed to minimize its occurrence. This paper investigates the fracture mechanisms of AA3105 aluminum alloy sheets during the flexible roll forming (FRF) process, focusing on methods to reduce damage and prevent failure throughout forming. Experimental tests were carried out to determine the mechanical properties of the sheet and to calibrate the modified Mohr–Coulomb fracture criterion. The digital image correlation technique was used to measure the experimental strain field at the onset of fracture. Finite element simulations of the calibration tests were then performed to validate the failure criterion, showing good agreement with experimental results. After calibration, the FRF process was simulated in ABAQUS, and a user subroutine was implemented to predict fracture evolution during forming. The simulation results were validated against experimental data obtained from the FRF machine, confirming the model’s accuracy. The results revealed that increasing the sheet thickness from 0.5 mm to 1.5 mm increased the damage at the critical element by approximately 52%, whereas increasing the transition radius from 250 mm to 550 mm and the bending radius from 1 mm to 3 mm reduced the damage by approximately 28% and 13%, respectively. In addition, increasing the number of forming stands reduced the damage by approximately 10%. These findings demonstrate that both thinner sheets and multi-stage forming significantly enhance formability and reduce fracture risk in FRF of aluminum sheets.

Journal of Manufacturing and Materials Processing doi: 10.3390/jmmp10100372

Authors: Jie Yi Kaiwen Yang Pengyu Fu Xing Xu Junfeng Xiang

Difficult-to-machine materials, including titanium alloys, nickel-based superalloys, hardened and high-strength steels, stainless steels, and fiber-reinforced composites, are widely used in advanced manufacturing but impose severe thermo-mechanical–chemical loads on cutting tools, resulting in progressive wear and degradation, localized damage, and, in severe cases, catastrophic failure. This review summarizes recent advances in tool condition monitoring and prognostics following the framework of material characteristics–tool deterioration mechanisms–condition sensing–predictive modeling–manufacturing decision making. The relationships between material properties and tool condition deterioration are first discussed, distinguishing progressive wear mechanisms, such as abrasion, adhesion, diffusion, and oxidation, from thermally induced degradation and localized damage phenomena such as cracking, coating delamination, and edge chipping. Direct tool measurement and indirect process-response monitoring based on force and torque, vibration and acoustic signals, thermal signals, and machine-tool electrical signals are then reviewed, while machining-quality characteristics are treated separately as machining-outcome-based condition indicators. Multisource information fusion is further discussed for integrating complementary tool condition information from these different sources. Tool condition assessment and prognosis are further examined in terms of wear estimation, tool-condition state identification, remaining useful life prediction, and catastrophic-failure risk prediction. Physics-based, data-driven, and hybrid models are compared with respect to accuracy, interpretability, uncertainty, and generalization. Finally, industrial deployment through online inference, edge-cloud collaboration, CNC integration, and digital-twin-supported closed-loop tool health management is discussed, together with key challenges in limited-data learning, cross-condition generalization, multimodal fusion, uncertainty quantification, standardized evaluation, and sustainable manufacturing.

Journal of Manufacturing and Materials Processing doi: 10.3390/jmmp10100371

Authors: Leandro Bolzoni Valentin Roduit Efrain Carreno-Morelli Fei Yang Stella Raynova

Reducing the cost of Ti alloys, both from a processing and compositional point of view, is a pathway forward for harnessing more extensively the industrial and environmental benefits associated with their uses, and it is an outstanding manufacturing challenge. Thus, this study investigated the manufacturing of a low-cost Ti alloy using different induction sintering strategies where both aspects are designed to reduce the final cost. The primary conclusion is that induction sintering of Ti alloys by cycling the temperature above and below the allotropic phase transformation (i.e., beta transus) suffices for the need for high green density values, which are commonly achieved using more expensive methods. This is due to faster densification kinetics. The fast uniform heating of the alloys leads to homogenous pore distribution in the entire volume and the dissolution of the alloying elements, especially during cycling sintering due to the fine particle size of the alloying elements. Consequently, despite the low homologous sintering temperatures used, the induction sintered low-cost Ti alloys do not fail catastrophically, although the ability to sustain plastic deformation is affected by the features of the residual porosity.

Journal of Manufacturing and Materials Processing doi: 10.3390/jmmp10090370

Authors: Nikolay Tonchev Miroslav Leventov Kokalarov Ivan Georgiev Nikolay Hristov Meglena Delcheva Lazarova

This paper presents an integrated modelling and decision-support reanalysis of a published 24-run experiment on diamond-spark grinding (electrical-discharge diamond grinding) of two hard alloys—the tungsten-free cermet TN-20 and the WC–TiC–Co alloy HS123—machined jointly with C45 steel; no new experiments are performed. Established components are deliberately combined into one reproducible workflow: quadratic response-surface models fitted by least squares and by minimax (Chebyshev) approximation, validation by prediction-oriented criteria including nested leave-one-out cross-validation of the entire model-selection pipeline, the addressable DEFMOT representation of the 94-factor grid formalized as an ε-constraint procedure, and benchmarking against desirability-function and Pareto analyses. Minimax fitting reduces the maximum absolute residual by 22.5–36.9% at the cost of higher aggregate errors. Nested validation exposes model-selection instability for the TN-20 responses, and a dedicated sensitivity analysis shows that the surrogate-model choice can change the recommended regime: the TN-20 compromise is efficient or one grid step from efficient under all three surrogate families, whereas the preferred HS123 regime shifts qualitatively (including a reversal of the wheel-speed setting) between least-squares and minimax surrogates. A residual-bootstrap analysis propagates data uncertainty through the complete optimization and quantifies how frequently each recommended regime is re-selected. Within the legacy cost basis, point estimates indicate comparable productivity (difference below 9%), an approximately 35% lower specific machining cost for TN-20 and approximately 1.8 times higher diamond consumption; the 95% confidence intervals for the between-material contrasts include zero, so experimental confirmation is required before industrial substitution. The framework quantifies, rather than hides, how surrogate uncertainty propagates into the engineering decision.

Journal of Manufacturing and Materials Processing doi: 10.3390/jmmp10090369

Authors: Jiaming Wang Taiki Tsuchiya Abrar Ahmed Seungwon Lee Kenji Matsuda

Post-quench natural aging can alter the response of Al–Mg–Si alloys to further artificial aging, while post-artificial-aging hardness, Hpost-AA, may obscure changes in the retained artificial-aging response. Five high-purity alloys containing 0.95–0.99 mol% Mg + Si, with Mg/Si ratios of 0.52, 1.1, 1.9, 3.0, and 4.0, were solution-treated at 848 K for 3.6 ks, quenched, and artificially aged at 473 K. Under direct artificial aging, after a minimum practical delay of approximately 0.1 ks, the Mg/Si = 1.1 alloy showed the highest Hpeak of approximately 72–73 HV0.1, whereas Mg/Si = 4.0 reached approximately 53–55 HV0.1. The precipitate areal density was highest near Mg/Si = 1 and decreased markedly in Mg-rich alloys. Operational HRTEM classification indicated that β″-related precipitates predominated in the Si-excess alloys, whereas β′-like and parallelogram-type precipitates were more prominent in the Mg-rich alloy. For Mg/Si ratios of 0.52, 1.9, and 4.0, quench-to-aging delays of up to 6000 ks produced non-monotonic changes in Hpost-AA. However, the additional hardening increment, ΔHAA, decreased from 38.5 to 26.1 HV0.1 at Mg/Si = 0.52 and from 33.5 to 26.9 HV0.1 at Mg/Si = 1.9. These results show that both Hpost-AA and ΔHAA are required to evaluate quench-to-aging delays.

Journal of Manufacturing and Materials Processing doi: 10.3390/jmmp10090368

Authors: Sergey N. Grigoriev Marina A. Volosova Yury A. Melnik Anna A. Okunkova Alexander S. Metel

Producing complex-shaped products of oxynitrides is one of the biggest challenges of the modern industry. The machining of those ceramics encounters challenges in terms of their physical and mechanical properties, such as their high brittleness and insulating electric properties. The problem may be solved by assisted electrical discharge machining by depositing multifunctional coatings by a plasma vacuum method that can contribute to electrical conductivity of the ceramic surface to provide wear-resistant properties. And that is the original solution because other authors either prefer using monofunctional coatings to provide electrical conductivity on the ceramic surface. The study employed TiN and quatronitride (Ti,Al,Cr,Si)N coatings, which were deposited on SiAlON samples. The adhesion strength and wire electrical discharge machining tests revealed the most favorable option (TiN coating) that demonstrated better adhesion and less brittle behavior. In addition to multifunctional coating, it is proposed to combine it with assisting powder by adding it in the interelectrode gap. MgO and CoO powder suspension (150 g/L) and erosion product suspension were chosen for kerf production. The MgO suspension was produced based on mineral oil, taking into account the chemical properties of magnesium-containing substances. Other suspension options were produced based on deionized water.

Journal of Manufacturing and Materials Processing doi: 10.3390/jmmp10090367

Authors: Tanuj Namboodri Csaba Felhő István Sztankovics

In thin-walled cylinder turning, wall thickness decreases with each pass. It reduces workpiece stiffness and shifts the stability limit of the cutting process. In this study, wall thickness and axial segment position are established as important factors that affect chatter occurrence in this geometry. To the best of the authors’ knowledge, there are no prior studies that used these geometric features as machine learning input. The objective of this study is to present a physics-informed framework for chatter detection in the thin-walled cylindrical turning of 1.4301 austenitic stainless steel. Five physics-informed features were extracted per segment: RMS resultant force, kurtosis, dominant non-harmonic frequency, normalized segment position and wall thickness. Four classical classifiers—Random Forest, Logistic Regression, Support Vector Machine (SVM) and Neural Network (NN)—are evaluated on 135 segments of 15 machining passes. For validation, Leave-One-Pass-Out (LOPO) cross-validation was performed. It holds out segments of each pass to reflect deployment conditions. Random Forest and Logistic Regression achieved above 95% recall and accuracy, exceeding the 90% safety threshold. A feature ablation study was performed to measure the importance and impact of individual input features; the results suggest that using geometric features achieves 100% recall with three classifiers. In addition, three validation schemes, LOPO, forward chaining, and fixed split, were used to evaluate the generalizability of the developed model. The non-tree classifiers ranked wall thickness and RMS cutting force as strong predictors, whereas the tree-based ensembles relied mostly on RMS. The results suggest that physics-informed feature engineering with classical ML is a promising approach for chatter detection in thin-walled cylindrical turning.

Journal of Manufacturing and Materials Processing doi: 10.3390/jmmp10090366

Authors: Panwen Su Ravi Menon Narayanan Murali Anoop Samant Bryan A. Webler Petrus C. Pistorius

Controlling the titanium concentration in weld deposits plays an important role in establishing weld metal microstructure. This work tested the effect of the reaction between the steel melt pool and liquid slag (molten flux) on titanium control during submerged-arc welding. Laboratory equilibration experiments confirmed that welding conditions are oxidizing towards titanium, with an expected equilibrium distribution coefficient of titanium between slag and metal of around 1000. Analysis of multilayer weld deposits confirmed the low recovery of titanium, but also a change in oxide inclusion composition in response to the titanium recovery in the weld metal. Both an approximate analytical model and a transient model considering full equilibration at the steel–slag interface demonstrated that titanium recovery is poorer if the steel–slag reaction proceeds further towards equilibrium. The relative importances—for the titanium concentration in the weld metal—of the rate of the steel–slag reaction and dilution of the added wire by remelted material are quantified with kinetic weighting factors. Considering these relative weights leads to general guidelines for control of the weld deposit composition.

Journal of Manufacturing and Materials Processing doi: 10.3390/jmmp10090365

Authors: Ella Spurina Alise Sapata Genadijs Sahmenko Vesna Zalar Serjun Lucija Hanzic Lidija Korat Bensa Evaldas Serelis Maris Sinka

This study presents the development and comprehensive characterisation of a sustainable 3D-printable cementitious composition in which up to 40 wt.% of Portland cement was replaced by a ternary binder containing oil shale ash (OSA) and metakaolin (MK). Following laboratory optimisation, the developed formulations were successfully transferred to industrial production as pre-blended dry mixes at Sakret Latvia Ltd., demonstrating the feasibility of large-scale manufacturing of printable cementitious materials. Attention was devoted to the characterisation of the raw materials and dry mixtures using particle size distribution (PSD), scanning electron microscopy with energy-dispersive spectroscopy (SEM/EDS), and X-ray diffraction (XRD). Two compositions—a reference mixture (REF) and the ternary OSA mixture—were evaluated in terms of printability, mechanical performance, durability, and the influence of the type of sample production. The ternary composition (due to the pozzolanic activity of MK and OSA) exhibited strength development resulting in compressive strength (60.6 MPa) exceeding that of the reference mixture after 90 days of curing (55.3 MPa). Mechanical testing of compression and flexural properties indicated direction-dependent differences between printed and cast specimens. Durability assessment, including capillary water absorption and surface freeze–thaw scaling tests performed using two standardised methods, confirmed frost resistance and the suitability of both mixtures for outdoor applications. The results further indicate that the layered manufacturing process governs moisture transport and direction-dependent mechanical behaviour associated with interlayer interfaces. The developed pre-blended OSA–MK composite represents a promising low-carbon material for industrial 3D concrete printing, combining reduced cement consumption with reliable printability, mechanical performance, and durability.

Journal of Manufacturing and Materials Processing doi: 10.3390/jmmp10090364

Authors: Rayson Pang Mun Kou Lai Siti Madiha Muhammad Amir Tze Chuen Yap

This study investigates the effect of reheating on previously deposited layers in material extrusion (MEX) 3D printing, commonly known as Fused Deposition Modeling (FDM), considering the combined effects of deposition sequence (unidirectional and bidirectional) and key process parameters, including printing temperature, printing speed, and layer height. Two temperature measurement methods were used to record changes during printing, and the results from local and global approaches were compared. The temperature of the interface between the first deposited layer and the build platform was measured with thermocouples. The findings show that the reheating effect at the first layer fades with increasing build layer, with no further increase in heating profile after the eighth layer, regardless of the process parameters investigated. The measured minimum temperatures at the investigated location remained above the glass transition temperature, Tg, which is critical for bonding and polymer chain rearrangement to continue taking place. Printing temperature was found to be the strongest observed factor influencing reheating, as it provides the heat for conduction into previous layers. Deposition sequence also played an important role, with bidirectional deposition leading to higher reheating and 25–50% more layers above the crystallization temperature, Tc. Overall, the results confirm that deposited roads undergo cyclic heating, and understanding the influence of process parameters on reheating is important for interpreting bond formation in MEX 3D printing.

Journal of Manufacturing and Materials Processing doi: 10.3390/jmmp10090363

Authors: Yueyu Huang Jianzhong Ye Xingxin Wei Ruilin Zeng Shequan Wang Ninghua Long Chao Yin Yuheng Bao Kongmin Yan Qun Wang

Valve sealing surfaces demand coatings with high load-bearing capacity, low friction, and corrosion resistance. This study presents a duplex coating system, comprising an AISI 4130 steel substrate, a WC-10Co4Cr interlayer, and a tetrahedral amorphous carbon (ta-C) top film—a hydrogen-free member of the diamond-like carbon (DLC) family—designed for such applications. A thick HVOF-sprayed WC-10Co4Cr interlayer (~300 µm, ~1100–1200 HV) provides mechanical support for a thin PVD-ta-C top layer (1.8 µm), preventing the “eggshell effect” on the soft steel substrate. A NiCr/Ti sublayer (650 nm) is added to improve compliance. Four systems—AISI 4130 steel substrate (S), single WC-10Co4Cr (WC), single ta-C, and duplex (WC-ta-C)—were tested under dry sliding (Al2O3, 20 N, 300 min) and in 3.5 wt.% NaCl solution. The duplex WC-ta-C coating achieves a mean CoF of 0.084 under dry sliding against Al2O3, representing a reduction of approximately 74% relative to the uncoated steel substrate. The corresponding specific wear rate is 2.08 × 10−8 mm3/(N·m), which is substantially lower than those of the single WC-10Co4Cr coating (by ~42%) and the single ta-C film (by ~90%), and more than three orders of magnitude lower than that of the bare steel. Electrochemically, WC-ta-C exhibits Ecorr = −0.181 V vs. SCE, Icorr = 1.19 × 10−8 A/cm2, and a total charge-transfer resistance Rtotal = 3.32 × 107 Ω·cm2, orders of magnitude higher than single coatings. These results demonstrate that the WC-10Co4Cr interlayer enables the ta-C layer to fully express its tribological and anti-corrosion functions, offering an effective surface strategy for valve seals in aggressive environments.

Journal of Manufacturing and Materials Processing doi: 10.3390/jmmp10090362

Authors: Thomas Reindl Georgij Safronov Stefan Rotzsche Tom-Eric Adams Peter Mayr Josip Vincic

Wire-arc directed energy deposition (WA-DED) using dynamic multi-axis hardware is typically restricted to a neutral position (90°), limiting process flexibility and full exploitation of multi-axis capabilities. To unlock torch positioning and stick-out distance as levers for tailored process manipulation, this study examines energy distribution across 124 samples using ER70S-6 filler wire. A 6 × 6 process window spanning wire feed speed (WFS = 2–7 m/min) and travel speed (v = 400–900 mm/min) was evaluated alongside continuous stick-out ramps (5–35 mm) and ten torch inclinations in push (45°, 60°, 75°), neutral (90°), drag (105°, 120°, 135°), and lateral (L15°, L30°, L45°) orientations. A synchronized multi-sensor framework captured electrical, thermographic, and melt pool dynamics while integrating airborne sound acoustic monitoring of process instabilities. Metallographic cross-sections, microhardness mapping, and EBSD grain analysis indicated microstructural shifts. Across the parameter matrix, volumetric energy density (VED) remained within 19–23 J/mm3 (measured), while thermal tracking revealed progressive heat accumulation. Stick-out extensions reduced heat input by 1.1–1.5%/mm, raising peak hardness in single beads from 290–310 HV to 350–385 HV. Torch orientation redistributed thermal energy at nearly constant heat and mass input. In the walls tested, melt pool length shifted by up to 30% and mean grain size by 11.1%, and penetration depth followed the push to drag sequence. Short-circuit frequency and cycle-period variation mirrored the approach to the humping limit, and acoustic envelope statistics accompanied overmelting. Thus, torch orientation and stick-out provide sensor-observable levers to influence process dynamics and component properties.

Journal of Manufacturing and Materials Processing doi: 10.3390/jmmp10090361

Authors: Michal Demko Marek Vrabeľ Jozef Brindza Ján Kušnír Todor Gavrilov Vladimír Pata

Surface roughness is a key quality characteristic in machining Invar 36 components used in dimensionally stable applications. This study evaluates the effects of cutting parameters on surface roughness and internal spindle torque during peripheral side milling of annealed Invar 36 and examines the feasibility of estimating roughness from CNC internal data. A Taguchi L9 orthogonal array was used to vary cutting speed, feed per tooth, and radial depth of cut. Surface roughness was measured by three-dimensional optical profilometry, while spindle torque was recorded at an 8 ms sampling interval. The first and final tool paths were analysed separately using Box–Cox-adjusted mean values. Feed per tooth and radial depth of cut were the dominant factors affecting roughness, whereas radial depth of cut had the strongest influence on torque. Within the investigated range of 20–40 m/min, cutting speed produced the smallest S/N response and was not statistically significant in the reduced models. Strong bivariate correlations were obtained (r = 0.938 and 0.932). The fitted linear relationships explained 88.1% and 86.9% of the in-sample variability. The results indicate potential for process-specific surface-roughness screening without a dedicated external torque sensor; however, the fitted equations require independent validation before predictive use.

Journal of Manufacturing and Materials Processing doi: 10.3390/jmmp10090360

Authors: Paolo Emilio Di Nunzio

Electrochemical permeation and thermal desorption spectroscopy (TDS) are widely used to characterize hydrogen transport and trapping in steels, but are commonly interpreted through separate modelling approaches. This work presents a unified one-dimensional kinetic framework for the coupled simulation of hydrogen permeation, room-temperature free desorption, and thermal desorption. Lattice diffusion is coupled with explicit McNabb–Foster trapping and detrapping kinetics for multiple effective trap populations characterized by their density and binding energy. The formulation enables the consistent transfer of hydrogen distributions and trap occupancies between successive simulation stages, thereby linking hydrogen uptake, retention, and release within a single framework. The kinetic equations are expressed in concentration form, employ the Eyring transition frequency, and recover the Oriani relationship as the equilibrium limit. Sensitivity analyses show that stationary permeation flux is governed primarily by charging concentration and specimen thickness, whereas permeation transients and residual hydrogen content are strongly affected by trapping. Thermal desorption peak temperature and shape depend on trap energy, trap density, diffusion length, and hydrogen distribution, demonstrating that peak position is not a unique measure of trap strength. Kissinger plots remain highly linear under all investigated conditions, although the recovered energies systematically underestimate the nominal trap energies and should therefore be interpreted as effective desorption parameters. An application to an industrial ferritic stainless steel demonstrates the practical use of the framework for interpreting complex TDS spectra and estimating effective trapping parameters. The framework provides a computationally efficient tool for integrated interpretation of hydrogen transport, trapping, and thermal desorption in steels.

Journal of Manufacturing and Materials Processing doi: 10.3390/jmmp10090359

Authors: Prakash Marimuthu Jana Petru Thenarasu Mohanavelu

Background: When a small design-of-experiments dataset is used to optimize a machining process with particle swarm optimization (PSO), the regression model chosen as the fitness function is rarely validated against more than one candidate response, checked against alternative model families, or checked for the optimization that follows from using the same cross-validation score to both tune and report a model. Methods: We revisit 24 end-milling trials on AISI 1045 steel (fifteen one-factor-at-a-time runs plus a Taguchi L9 array; every value was independently verified against the underlying thesis records) in which cutting force, cutting-zone temperature, and X-ray diffraction residual stress were measured. A multiple linear regression (MLR), a quadratic response-surface model (RSM), a support vector regression (SVR), and a Gaussian process regression (GPR) were each cross-validated by nested leave-one-out cross-validation against every response, with bootstrap 95% confidence intervals and paired bootstrap significance tests on the resulting R2 values, as well as a variance-inflation-factor check on the combined design matrix. The best-validated model per response was then used inside an identical constricted-PSO routine, which was run across 30 random seeds per fitness function to assess the convergence stability. Results: Design collinearity was not a concern (all VIF ≤ 1.28). Under the nested validation, the response-specific pattern held for temperature and residual stress but not for cutting force: the SVR was the only model to beat the MLR by a margin that survived a paired bootstrap test (residual stress, P (SVR not better) = 0.02); for force, a quadratic RSM model outperformed all three other families (R2 = 0.72 vs. 0.39 for MLR and 0.28 for GPR), and the GPR’s earlier apparent advantage for force did not survive the leakage-free hyperparameter selection. The residual-stress PSO result was stable across seeds: 27 of 30 of the SVR-fitness runs converged to the same interior optimum (579.8 rpm, 40 mm/min, 0.413 mm; mean −472.5 MPa, SD 3.4 MPa), against a boundary optimum found deterministically by every MLR-fitness run (355 rpm, 40 mm/min, 0.5 mm, −434.6 MPa). The validated interior optimum also predicted a 55% lower cutting force and a slightly lower temperature at the same operating point. Conclusions: Whether a nonlinear surrogate should replace a linear one is response-specific and must be checked with a leakage-free validation scheme rather than assumed; for this dataset, that check overturns the original force-model recommendation while confirming the residual-stress result under both cross-model and multi-seed checks. The residual-stress optimum remains a model prediction pending physical confirmation.

Journal of Manufacturing and Materials Processing doi: 10.3390/jmmp10090358

Authors: Wanglin Dai Dongqing Cai Wenkai Luo Fenglei Li Victor Komarov Roman Karelin Dongdong You

To further refine rehabilitation protocols for transverse patellar fractures, this study conducted numerical simulations in Abaqus to investigate the interaction between a nickel–titanium shape-memory-alloy patellar concentrator and fractured patellar bone under variations in patellar loading, quadriceps muscle tension, knee-flexion angle, and fracture-site width. Lower knee-flexion angles primarily generated bending moments in the patellar concentrator, whereas greater flexion angles primarily generated tensile forces. Across the simulated knee-flexion range of 0–150°, the predicted quadriceps muscle force ranged from 240 to 670 N. Based on the simulated mechanical response, under the prescribed modeling assumptions, the 60–90° knee-flexion range showed a comparatively favorable balance between predicted fracture closure and implant loading. Comparison with previously published computational studies showed that the loading and angular conditions examined in this study were within the ranges reported in the literature, while extending the analysis to less frequently studied flexion conditions. However, because direct experimental validation, mesh-convergence testing, and comprehensive sensitivity analysis were not included, these values should be interpreted as model-based estimates requiring further experimental and clinical validation.

Journal of Manufacturing and Materials Processing doi: 10.3390/jmmp10090357

Authors: Gianluca Palangio Maria Pia Desole Massimiliano Barletta Annamaria Gisario

The spunbond process is one of the main technologies for producing polypropylene (PP)-based nonwoven fabrics, widely used in industrial applications and in the automotive sector. In this work, an injection-molding-grade polypropylene was modified through the addition of 0.5 wt% Nexamite R202, a concentration representative of the levels typically employed in commercial controlled-rheology grades for spunbond applications. The effects of controlled degradation on the material’s properties were then evaluated, together with its potential suitability to produce nonwoven fabrics intended for car cover coatings. Characterization included mechanical tests (tensile and impact), thermal analysis (DSC, VICAT) and rheological measurements. The results show that peroxide addition increases melt flow rate (MFR) from 12.5 to 33.3 g/10 min (+167%), reduces capillary viscosity, lowers the maximum tensile stress from 25.5 to 22.7 MPa, keeps the strain at break statistically comparable (18.9% to 18.6%) and reduces the impact energy from 139.6 to 102.2 kJ/m2. In the regrading stage, formulation SB#4, containing a regrading additive, antioxidants, and a virgin fraction, showed the best compromise between processability and toughness, although without fully restoring the properties of the virgin material. These results indicate that a combined regrading strategy represents an effective route for valorizing reprocessed PP within a circular economy framework.

Journal of Manufacturing and Materials Processing doi: 10.3390/jmmp10090356

Authors: Afshin Tanouri Afrooz Bayat Matthew Stephenson Angie Shafei Reza Shabahang

This study aimed to investigate the application and perceptions about the use of immersive technology-based training in manufacturing contexts. This study employed a quantitative approach surveying a total of 1000 manufacturing professionals in Australia regarding their perceptions of workplace training, as well as immersive-based training, using self-report questionnaires. Descriptive statistics, Pearson correlation analysis, and structural equation modelling were employed for statistical analyses using R software. In the structural equation model, controlling for demographic variables, perceived benefits of workplace training were positively associated with positive anticipation, perceived usefulness, and perceived ease of use of immersive technologies in workplace training. In contrast, perceived value of learning through workplace training was associated only with perceived ease of use of immersive technologies in workplace training. This study suggests general optimistic views toward immersive workplace training in the Australian manufacturing sector, particularly the extent to which they perceive workplace training as beneficial rather than aligned with individuals’ value. Given the ongoing need for continuous skill development in manufacturing, the increasing reliance on immersive technologies for training purposes, and promising outcomes associated with such approaches, increasing acceptance of immersive technology-based training warrants consideration.

Journal of Manufacturing and Materials Processing doi: 10.3390/jmmp10090355

Authors: Jorge Jiménez-Armendáriz Mariel Alfaro-Ponce Moises Jimenez-Martinez

The mechanical properties of fiber-reinforced polymer matrix composites are largely influenced by the characteristics of their constituents, including the matrix and fibers. During injection molding, various process parameters such as thermal and pressure variations play a critical role in shaping the final properties of the molded parts. This study investigates the impact of key process parameters controlling the solidification of glass fiber-reinforced polypropylene (PPGF) plates, including injection temperature and packing pressure, on warpage, hardness, tensile strength, and flexural properties. To the best of the authors’ knowledge, studies on the characterization of changes induced in flexural properties by modifications to injection molding process parameters in fiber-reinforced polymers are limited. Through a statistical analysis, the relationship between process parameters and the contribution of fibers to the composite’s mechanical performance is assessed by comparing the properties of reinforced and unreinforced materials. While the addition of fibers tends to increase warpage, optimal combinations of process parameters significantly reduce warpage while enhancing mechanical properties such as tensile and flexural moduli. These findings offer valuable insights into optimizing injection molding conditions to minimize warpage and improve mechanical properties.

Journal of Manufacturing and Materials Processing doi: 10.3390/jmmp10090354

Authors: Saravanamurugan Sundaram Jana Petru Karjagi Kiran Suresh Awsan Mohammed Thenarasu Mohanavelu

Regenerative chatter severely limits productivity in machining operations, and tuned mass dampers (TMDs) are widely used for passive chatter suppression. However, most existing TMD designs neglect workpiece dynamics and rely on two-degree-of-freedom assumptions, leading to suboptimal performance when tool and workpiece dynamics are comparable. This paper presents a three-degree-of-freedom analytical stability model incorporating the coupled dynamics of the cutting tool, workpiece, and TMD. Stability lobes are derived in the frequency domain, and a max–min optimization strategy is proposed to determine optimal TMD parameters across varying workpiece dynamic conditions. The results indicate that variation in workpiece dynamics significantly hinders the improvement in machining stability achieved by the TMD, and its effectiveness is drastically affected when the cutting tool and workpiece have similar dynamic characteristics. To enhance TMD effectiveness in changing workpiece dynamic conditions, tuning parameters should be optimized to reflect these variations. The proposed analytical and optimization framework may provide a basis for future adaptive chatter-control systems that identify changes in tool–workpiece dynamics online and use them to determine appropriate absorber tuning parameters. However, the present study is limited to offline optimization of a passive TMD and does not implement real-time parameter adaptation. Experimental validation using an additively manufactured TMD demonstrates a clear modification of the fundamental dynamic behaviour, wherein the original single resonance is split into two distinct natural frequencies. Though the extent of this frequency separation is marginal, a significant reduction in peak amplitude is observed: 91% in the low-stiffness workpiece and 69.8% in the high-stiffness workpiece, indicating stronger interaction between the absorber and the machining system under compliant conditions.

Journal of Manufacturing and Materials Processing doi: 10.3390/jmmp10090353

Authors: Tiaoqi Fu Mingxing Li Bing Peng Jincheng Zhang Gaowei Li Xiaowang Sun Tao Wang Xianhui Wang

Conventional design paradigms for vehicle underbody armor face an inherent trade-off: enhancing blast protection invariably incurs a prohibitive weight penalty. Here, we investigate a mechanical pre-stressing strategy for high-strength steel V-shaped vehicle underbody structures. A conventional V-shaped baseline structure was first subjected to a 6 kg TNT blast test, and the measured response was used to validate the numerical model. Based on the validated numerical model, four mass-equivalent (100 kg) configurations were subsequently compared numerically under escalating threats (2~8 kg TNT): pre-stressed steel, homogeneous steel, and all-metallic honeycomb sandwich panels (comprising high-strength steel face sheets and an aluminum alloy core) with both positive and negative Poisson’s ratios. The numerical results predict that the pre-stressed steel configuration exhibits the smallest maximum permanent floor deformations among the four configurations, with values of 22 mm, 46 mm, 131 mm, and 208 mm under 2, 4, 6, and 8 kg loads, respectively. Mechanistically, we reveal that for V-shaped geometries, residual-stress-induced stiffening and geometric arching are profoundly more effective than core crushing in controlling global bending, while the auxetic steel-faced aluminum honeycomb offers only marginal improvements over its conventional counterpart. This study offers a potential pathway for overcoming the weight–protection trade-off in underbody armor design. While the numerical predictions are encouraging, direct experimental validation of the pre-stressed configuration remains necessary prior to practical application.

Journal of Manufacturing and Materials Processing doi: 10.3390/jmmp10090352

Authors: Massimiliano Ceppi Mumtaz Alam Hafiz Federico Scalzo Barbara Motyl Marco Sortino

Manufacturing-as-a-service (MaaS) platforms require fast and accurate manufacturing cost estimation to support quotation and resource allocation across distributed networks. However, existing machine learning approaches are often constrained by limited data availability, proprietary information, and insufficient interpretability. This work presents an engineering-based framework for generating high-fidelity synthetic data to develop scalable and interpretable cost estimation models, culminating in a SHAP-interpreted XGBoost model. A parameterized prismatic workpiece was sampled using a Hammersley sequence design of experiments, producing 1355 geometrically feasible parts with representative drilling and pocket milling features. For each configuration, cutting tools, machining parameters, and CNC toolpaths were automatically generated and optimized through an integrated SolidWorks, MATLAB, and VERICUT workflow. Over 70,000 physics-based simulations were performed to obtain reference values for machining time, tool usage, and manufacturing cost. The resulting dataset integrates geometric descriptors and optimized process parameters, enabling the training and evaluation of machine learning models. The proposed methodology demonstrates that engineering-driven synthetic data provides a physically consistent foundation for fast and interpretable AI-enabled cost estimation. While applied to a specific family of three-axis milled parts, this approach serves as a proof-of-concept for predictive micro-services required in next-generation platform-based manufacturing systems.

Journal of Manufacturing and Materials Processing doi: 10.3390/jmmp10090351

Authors: Angelos Kourepis Nikolaos Kladovasilakis Elias D. Georgakoudis Michael A. Madas

Finite-buffer production systems are widely used in manufacturing, where performance depends on the interaction among machine reliability, buffer capacity, and maintenance policies. This study proposes a unified Continuous-Time Markov Chain (CTMC) framework for modeling and comparatively evaluating alternative finite-buffer production systems. Three configurations are considered: a serial production line with unreliable machines, a workstation-based system with parallel machines, and a condition-based maintenance system incorporating multi-state machine degradation and preventive maintenance. For each configuration, the state space, transition structure, infinitesimal generator matrix, and steady-state probability distribution are derived to estimate throughput, work-in-process inventory, cycle time, and total operating cost. Numerical experiments investigate the effects of buffer capacity, workstation parallelization, maintenance policies, degradation severity, reliability parameters, and financial factors. Under the baseline setting, the conventional serial configuration achieves a throughput of 0.8300 products/min, while workstation parallelization increases throughput to 1.6840 products/min, corresponding to a 102.9% improvement. The condition-based maintenance configuration achieves 0.8173 products/min while accounting for equipment deterioration and preventive-maintenance interventions. Overall, the framework enables the consistent evaluation of operational and economic trade-offs and supports production planning, maintenance optimization, and manufacturing system design.

Journal of Manufacturing and Materials Processing doi: 10.3390/jmmp10090350

Authors: Yanju Wang Xufeng Song Shehui Tang Qun Li Hongyi Du Quanyi Zuo Erbo Liu Qingqing Lü Liquan Yang

The GH4202 nickel-based superalloy is widely used in aero-engine hot-section components, where surface integrity is critical to fatigue performance. This study combined Abaqus/Explicit 2023 single-shot simulations, single-factor experiments, and an L16(44) orthogonal array to evaluate the effects of shot diameter, peening duration, pressure, and impact angle. Qualitative single-shot simulation results show that an increase in the prescribed impact velocity leads to higher simulated compressive residual stress and plastic deformation, whereas the growth rate slows down significantly when the velocity exceeds 30 m/s. Orthogonal main-effect analysis indicated that pressure had the greatest effect on Ra, whereas duration had the greatest effect on HV0.1. The Pareto evaluation identified Runs 1, 6, 11, and 16 as non-dominated combinations. A3B3C1D2 (0.8 mm, 45 s, 0.2 MPa, and 45°) was selected as a representative intermediate compromise for characterization and independent confirmation. The confirmation batch yielded Ra = 0.243 μm and HV0.1 = 345.3 HV. Within the tested domain, the candidate ranges for subsequent validation were 0.6–0.8 mm, 30–45 s, 0.2–0.3 MPa, and 45–60°.

Journal of Manufacturing and Materials Processing doi: 10.3390/jmmp10090349

Authors: Rafaa Saaidia Houcem Ltaeif Imed Miraoui Abdallah Bouabidi Arman Ameen Lazhar Ayed

This study explores the development of sustainable composite materials based on phosphogypsum (PG), an abundant industrial by-product, reinforced with olive and eucalyptus wood chips. The objective is to valorize waste streams while enhancing the mechanical, thermal, and acoustic performance of the base material for eco-efficient construction applications. Composites were prepared with fiber contents of 5%, 10%, 15%, and 20% and evaluated through standardized experimental tests. Mechanical behavior was assessed via three-point bending tests, revealing a 26% improvement in flexural strength at 15% eucalyptus content. Water absorption increased with fiber content but remained lower in eucalyptus-reinforced composites due to better fiber–matrix cohesion. Thermal conductivity decreased significantly from 5% to 20% fiber content, reaching 0.60 W/m·K at 20% eucalyptus content, indicating enhanced insulation potential. Acoustic tests, performed using an impedance tube in accordance with ISO 10534-2, showed strong frequency-dependent absorption. The 20% olive composite achieved a peak absorption coefficient of 0.78 and an NRC of 0.68, demonstrating excellent sound-damping characteristics. This work introduces a novel integration of two underutilized Mediterranean biomasses into PG matrices and highlights their multifunctional benefits. The resulting composites offer a low-cost, low-carbon solution for thermally and acoustically optimized building components, advancing circular economy principles in the construction sector.

Journal of Manufacturing and Materials Processing doi: 10.3390/jmmp10090348

Authors: Yura Choi Jinyoung Kim Namchul Cho

The uniformity of polymer matrices can strongly influence pattern retention during negative-tone development. In this study, two 3-arm star terpolymers, designated HTM Random and HTM Block, were synthesized via reversible addition–fragmentation chain transfer polymerization using simultaneous and sequential monomer-addition strategies, respectively. Both polymers were prepared using the same nominal feed ratio of 2-hydroxyethyl methacrylate, dicyclopentanyl methacrylate, and 2-methyl-2-adamantyl methacrylate. Although the two materials exhibited controlled molecular weight distributions and similar FT-IR spectral changes after ultraviolet exposure and post-exposure baking, differences were observed in their chain-packing characteristics, thermal behavior, and developed pattern morphology. The two materials exhibited comparable initial thermal stability but distinct multistep degradation profiles and glass-transition behavior. In contrast, the simultaneous-feed material showed more clearly retained and spatially uniform patterns under the tested development conditions. These results indicate that the materials produced by the two monomer-addition strategies exhibited differences in thermal response and development behavior under the investigated conditions.

Journal of Manufacturing and Materials Processing doi: 10.3390/jmmp10090347

Authors: Masoud Ahmadnia Eskandar Fereiduni Mohamed Elbestawi

The Fe–6.5 wt.% Si alloy is a promising soft magnetic material for electric motor applications owing to its high electrical resistivity and low core loss. However, the intrinsic brittleness of this alloy precludes fabrication of thin laminates using conventional rolling processes. Laser Powder Bed Fusion (LPBF) has therefore been considered as an alternative manufacturing route, offering both geometric flexibility and the inherent advantages of additive manufacturing. Nevertheless, successful LPBF processing of Fe–6.5 wt.% Si has remained challenging due to its high-silicon content. In this study, the Fe–6.5 wt.% Si alloy was modified by introducing 1 wt.% Cr, and LPBF process variables were optimized to yield defect-free parts. The effect of Cr addition on suppressing the disorder–order phase transformation during solidification was investigated through Thermo-Calc® thermodynamic simulations and quantified via X-ray diffraction phase analysis. Crack morphology analysis from optical micrographs revealed a marked reduction in both solidification and liquation cracks, attributed to the role of Cr in mitigating silicon segregation and consequently lowering the fraction of ordered phases. Preheating the build plate to 200 °C was found to effectively eliminate vertical cracks by reducing thermal stresses within the parts; however, a limited number of horizontal cracks initiated at the sample edges and propagated inward, likely due to elevated thermal gradients at the perimeter. To address this issue, sacrificial walls were introduced at distances of 1.0 mm and 0.2 mm from the cube edges, locally reducing the cooling rates and effectively increasing the primary dendrite arm spacing (PDAS). The reduced cooling rate also led to lower lattice misorientation, confirmed by electron backscatter diffraction (EBSD), and a significant decrease in the crack length from ~2 mm to ~0.7 mm.

Journal of Manufacturing and Materials Processing doi: 10.3390/jmmp10090346

Authors: João Paulo Nobre Thorsten Manns Altino Loureiro

This study provides a detailed comparison between X-ray diffraction (XRD, sin2ψ method) and incremental hole-drilling (IHD, regularised integral method) for assessing residual stresses in steel plates MAG-welded with three commonly used joint configurations (II-, X- and V-grooves), with and without mechanical constraints. Surface and in-depth residual stresses were evaluated on both faces of each sample, supported by hardness and metallographic analysis. After removal of the mechanical constraints and sectioning, XRD revealed similar tensile stresses at the weld toe for all joints, with longitudinal values of approximately +200 MPa, but marked differences at the weld centre, where compressive stresses of approximately −390 MPa were measured in the II-joint, associated with the combined effects of groove geometry, welding sequence and pass-specific heat input during welding under common restraint conditions. IHD provided smooth depth profiles but consistently overestimated stress magnitudes relative to XRD, with differences reaching approximately 150–200 MPa at depths ≥ 0.2 mm in the X-joint. Plasticity effects were identified as an important contributor to these discrepancies. The plasticity factor was used as a complementary indicator of when local yielding may influence IHD results, exceeding the adopted reference value of f=0.2 near the surface in all joint configurations and supporting the interpretation that yielding occurred during the first drilling increments in all joints. The integral method, used for non-uniform in-depth stress evaluation by IHD, propagates near-surface inaccuracies into deeper layers. A preliminary application of a plasticity-correction procedure, developed for uniform stress fields, reduced IHD stresses but was not fully effective. Overall, the results highlight the strengths and limitations of XRD and IHD for residual-stress evaluation in MAG-welded joints and emphasise the need for caution—and ideally correction—when applying IHD to determine welding residual stresses.

Journal of Manufacturing and Materials Processing doi: 10.3390/jmmp10090345

Authors: Alexander Schilling Andrea Knöller Philipp Ninz Wolfgang Eberhardt Frank Kern André Zimmermann

Due to the superior thermal, mechanical and chemical properties of ceramics, metallized ceramics are widely used as circuit carriers and interconnect devices, wherever standard polymer-based circuit boards come to their limits. 2D metallization represents the current state of the art. The metallization of 3D-shaped ceramics cannot be achieved with standard metallization techniques, such as screen printing, but, for example, with the so-called laser-induced direct metallization (LDM). For LDM, a pulsed laser is used to locally activate the ceramic surface, followed by a selective electroless copper plating on the laser-irradiated areas. Although it has already been shown that LDM on Al2O3-based ceramics is possible with different laser systems, a comprehensive study on the effect of different laser parameters on ablation and activation, which includes the influences of structuring on inclined surfaces, has not been done yet. In this study, laser power, pulse repetition frequency, pulse overlap and the number of passes were varied systematically to determine the parametric sensitivity of the ablation and metallization behavior for pulsed infrared laser activation of Cr2O3-doped ZTA. It was found that ablation is necessary for the metallization and that the peak fluence is the governing factor for the ablation and metallization process. It was further shown that ablation can be well predicted with an accumulated fluence, which includes pulse overlap. Structuring under an inclination angle up to 60° does not result in a reduced activation or adhesion strength of the deposited copper. Injection-molded 3D ceramic substrates were successfully metallized and functionalized by applying an optimized set of laser parameters, showing that LDM enables the functionalization of complex 3D ceramic substrates and therefore opens up new possibilities for integrated ceramic circuit carriers.

Journal of Manufacturing and Materials Processing doi: 10.3390/jmmp10090344

Authors: Prachid Saramolee Siraporn Sakphrom Choosak Rittiphet Supawat Kotchparadit Koki Ogura Sarawuth Chaimool

Encapsulation for wireless dairy-cattle implants must resist acidic, moisture-rich gastrointestinal conditions while remaining transparent to radio-frequency (RF) signals. This study evaluated vulcanized natural rubber (NR) latex as an intraruminal encapsulant, examining how total solid content (TSC; 30, 40, 50 wt%), stirring duration (24–72 h), and TiO2 loading affect tensile and tear strength, acidic swelling, dip-coating thickness, and received signal strength indicator (RSSI) at 433 MHz. Multilayer dip-coating produced films 0.25–0.38 mm thick. Tensile strength rose with TSC and stirring (26.6 → 32.2 MPa), whereas tear strength peaked at 40 wt% (31.97 N mm−1). Adding 5 phr (parts per hundred rubber) TiO2 cut pH-4 swelling ~four-fold (21.1 → 5.25%) with a negligible RSSI penalty, and 3–5 coating layers kept the link well above the −120 dBm sensitivity floor over 5–55 m. The optimum—40 wt% TSC, 72 h stirring, 5 phr TiO2—best balanced mechanical integrity, swelling resistance, thickness, and wireless performance. Vulcanized NR is therefore a promising bio-based encapsulant under simulated conditions; dielectric characterization, long-term aging, and in vivo validation remain future work.

Journal of Manufacturing and Materials Processing doi: 10.3390/jmmp10090343

Authors: Mohsen Lalehparvar Alex Nuttall Dhruva Bavaria Felix Massó Etxeberria Kaustubh Dwivedi Hessam Ghasemnejad Pablo Coladas Mato Wydo van de Waerdt

Bird strikes cause aircraft damage, create serious risks to human safety and can contribute to catastrophic incidents, while continuing to impose substantial economic costs on airlines. The impact combines high kinetic energy with discontinuous, strongly nonlinear contact over a short duration, producing large structural deformations; appropriate nonlinear simulation techniques are therefore required to capture this complex interaction. For this purpose, the present study applies established Smoothed Particle Hydrodynamics (SPH)–finite element modelling ingredients to a controlled matrix of aerospace material systems and target geometries. The approach is first benchmarked against a published aluminium flat-plate bird-impact test using a raster-digitised force-history comparison, after which monolithic metallic and composite structures and source-described honeycomb-sandwich alternatives are assessed in flat-panel and curved leading-edge configurations. The results show that contact-force and local-displacement rankings depend strongly on target geometry and response metric, with the curved leading edge changing the ordering observed for the flat panel. More compliant systems generally permit greater local displacement, whereas stiffer systems restrict displacement but can sustain higher short-duration force peaks; consequently, no universal material ranking follows from a single response measure, and the results are most suitable for preliminary design screening.

Journal of Manufacturing and Materials Processing doi: 10.3390/jmmp10090342

Authors: Fatema Tuz Zohra Hribhu Chowdhury Bahram Asiabanpour

The performance of Peltier-driven atmospheric water generation (AWG) systems depends strongly on the surface geometry and wetting behavior of the condensation structure. Triply periodic minimal surfaces (TPMS) provide high surface area-to-volume ratio and geometric tunability, but their effectiveness as three-dimensional condensation structures requires experimental evaluation. In this study, five additively manufactured TPMS geometries, Gyroid, Diamond, Lidinoid, SplitP, and Schwarz, were evaluated in a Peltier-driven AWG setup under controlled laboratory conditions. The measured water collection response varied among the tested TPMS geometries, which showed different condensation, retention, and collection trends. Water collection was measured with and without surface treatment, while the monitored surface temperature remained below the calculated dew point during testing. Without surface treatment, total water collection ranged from approximately 0.9 to 1.4 g, whereas surface-treated specimens collected approximately 0.6 to 1.2 g. The specimens with surface treatment exhibited predominantly discrete droplets rather than the film-wise morphology observed without surface treatment, but the total water collection did not increase consistently. Gyroid and Lidinoid showed slight increases with surface treatment, while SplitP, Diamond, and Schwarz showed reductions. Water collection also did not scale directly with calculated TPMS surface area, which suggests that effective air exposure, droplet retention, drainage, and coating uniformity contributed strongly to the observed performance. These findings provide experimental insights into additively manufactured TPMS geometry and surface treatment conditions for Peltier-driven AWG.

Journal of Manufacturing and Materials Processing doi: 10.3390/jmmp10090341

Authors: Sanjeevi Sharma R Venkatachalaiah K N Ramakrishna Pramod M. E. Shashi Kumar

Laser powder bed fusion (LPBF) is a disruptive additive manufacturing process for producing high-performance Inconel superalloy parts with complex shapes for the aerospace, energy, and other demanding industries. However, uniform part quality remains a persistent challenge, as process parameters, melt-pool dynamics, microstructural evolution, defect formation, and mechanical performance are closely coupled across a wide range of spatial and temporal scales. In previous reviews, these dimensions have been considered in isolation with limited insight into their interactions and implications for predictive process control. The present review aims to address this lacuna by proposing a unified Process–Structure–Property–Control (PSPC) framework for LPBF-produced Inconel 625, 718, and 738. The discussion begins with material attributes governing alloy processability, and then synthesises the melt-pool physics governing thermal behaviour, solidification, and energy transfer. Attention then turns to a critical assessment of grain evolution, defect formation, and process stability, showing how the thermal history governs microstructural development and, in turn, mechanical performance via linked process–structure–property relationships. Progress in multiscale numerical modelling, such as finite-element analysis, computational fluid dynamics, phase-field modelling, cellular automata, and phase-diagram calculation (CALPHAD), is reviewed to establish a comprehensive modelling ecosystem for predictive LPBF. The review also discusses the potential of emerging technologies, such as beam shaping, multi-laser processing, in situ monitoring, artificial intelligence, and powder recyclability, to increase the robustness and productivity of the process. Building on these advances, a digital-twin-enabled predictive-manufacturing framework that integrates physics-based models, data-driven algorithms, and real-time monitoring is introduced to enable closed-loop process optimisation. The review ends with a scientific synthesis and future research roadmap for intelligent, reliable, and autonomous LPBF of next-generation Inconel superalloys.

Journal of Manufacturing and Materials Processing doi: 10.3390/jmmp10090340

Authors: Vladimir Zagoya-Juárez Héctor Plascencia-Mora Jaime Navarrete Damián Ismael Ruiz-López Juan Francisco Reveles Arredondo María Cristina López-Mendez

Injection molding is a plastic material processing technique used in the polymer industry. Because it is a complex process that requires injection cycles to achieve the desired aesthetic quality in the molded parts, it is essential to evaluate and configure all process parameters to predict and reduce defects, thereby decreasing the processing time and energy consumption. This study presents the results of tests performed on molded HDPE parts, including modeling and simulation using ANSYS® (2025 R1), a design of experiments (DOE), and 3D scanning of the molded parts. The study compares the behavior of defects (warpages and sink-marks) in molded parts using 3D scanning with the results obtained from coupled thermal-structural field finite element simulations. These simulations were performed using software to assess the residual thermal stress of the ejection phase. The results visually display information that helps designers and engineers in the polymer processing sector evaluate molding-process failures using different software.

Journal of Manufacturing and Materials Processing doi: 10.3390/jmmp10090339

Authors: Oleksandr Burdin Armin Schleinitz Florian Morczinek Martin Dix

The environmental impact of technical systems is becoming increasingly important. Particularly in mechanical engineering, with its high demands on process stability and product quality, environmentally beneficial materials such as wood, with its heterogeneous and anisotropic structure, present challenges. Therefore, understanding the cutting process and the cutting forces is of great importance. This publication builds upon an established cutting force model and presents experiments to determine the specific cutting force (kc0.5) and normal cutting force (kcn0.5) for birch plywood. Furthermore, the influence of the rake angle (Kγc and Kγcn) and the cutting speed (Kvc and Kvcn) on the cutting forces is investigated. These correction factors are integrated into the established cutting model and verified under the assumption of no relevant directional dependence of the cutting forces due to the fibers of the plywood under investigation at the macroscopic level. The correction factors were determined based on the experiments and show a high degree of agreement with experimentally measured values. The correction factors lead to an increase in accuracy of predicting cutting forces during the peripheral milling of birch plywood. The model enables the prediction of cutting force with an average 30% increase in accuracy compared to the reference model. The results thus allow for a more accurate description of the cutting forces, from which important insights can be derived in the future for optimizing the cutting process and the tool, as well as for addressing tool wear and process quality.

Journal of Manufacturing and Materials Processing doi: 10.3390/jmmp10090338

Authors: Sun Jeong Hwang Hae June Lee

Wafer-edge uniformity is a critical issue in plasma etching because local variations in ion bombardment can directly affect the etch profile and process yield. Ion transport near the wafer-edge is strongly influenced by the sheath formed around the boundary between the wafer and the focus ring. Although focus ring geometry, dielectric properties, and applied voltage conditions can all modify this local sheath, their respective roles in controlling ion incidence angle and energy have not been clearly distinguished. In this study, two-dimensional particle-in-cell Monte Carlo collision simulations were performed for an argon capacitively coupled plasma to compare the effects of focus-ring height, electrode-to-focus-ring gap width, dielectric permittivity, and applied voltage conditions. The electrical conditions included a single-frequency waveform and a pulsed dual-frequency waveform with a variation in the low-frequency (LF) voltage amplitude. Geometric changes in focus-ring height and gap width modify the local sheath contour and ion acceleration direction, leading to more pronounced changes in the ion incidence angle than those caused by dielectric permittivity. The ion energy, however, is more strongly influenced by the applied voltage condition, particularly the LF voltage amplitude. These findings provide fundamental insights into wafer-edge ion control, although their quantitative applicability to reactive and electronegative etching remains to be verified.

Journal of Manufacturing and Materials Processing doi: 10.3390/jmmp10090337

Authors: Luis Alberto Flores Chaires José Ricardo Gómez Rodríguez Hugo Pineda Martínez Ana Gabriela Castañeda Miranda Remberto Sandoval Aréchiga Víktor Ivan Rodríguez Abdala Salvador Ibarra Delgado Oscar Osvaldo Ordaz-García

Small-scale clay-brick yards require molding equipment that increases output while remaining mobile, locally serviceable, and compatible with intermittent material supply. This article documents the functional architecture and exploratory operational performance of the mobile 12-cavity hydraulic clay-brick molding machine (ML12). Its design contribution is the integration of a dimensioned wheeled steel chassis, seated paired-lever controls, a translating feed hopper/distributor, a 12-cavity mold, two vertical hydraulic actuators, and a water-spray cleaning subsystem in a four-stage operating cycle. A retrospective concept-appraisal matrix compares this architecture with fixed automated and mobile manual concepts; equal weighting and one-at-a-time ±25% weight variations preserve the ML12’s highest internal score, without establishing stakeholder preference or empirical superiority. The evidence base also comprises sequential daily production logs: ten days of traditional manual molding followed by ten days of ML12-assisted molding. Mean gross green-brick output was 720 ± 86 bricks/day in the traditional period and 1495 ± 16 bricks/day in the ML12 period; corresponding descriptive throughputs were 86.5 and 186.9 bricks/h. A rejection-rate sensitivity analysis shows that, if traditional production had no rejects, ML12 conforming output would equal the traditional gross mean at a 51.8% ML12 rejection rate; this quantity boundary is not an estimate of quality or economic break-even. A preliminary linear-static finite-element case for a reconstructed frame returned a maximum von Mises stress of 112.3 MPa, 1.82 mm resultant displacement, and a minimum elastic safety factor of 2.23 on the reported medium mesh; the result is limited to the specified 1.0 kN load case and is not structural certification of the complete machine. Because the operational comparison was non-randomized and did not control staffing, operators, clay batch, moisture, weather, energy use, or rejection rate, the observed difference cannot be attributed exclusively to the machine. The results establish the machine architecture, an operational signal, and a bounded preliminary frame response, but not brick quality, ergonomic benefit, full structural safety, environmental benefit, or commercial return.

Journal of Manufacturing and Materials Processing doi: 10.3390/jmmp10090335

Authors: Mohammad Mehdi Kasaei

The continuing evolution of transportation, aerospace, energy, electronics, and other high-performance engineering sectors is placing increasingly demanding requirements on manufacturing technologies [...]

Journal of Manufacturing and Materials Processing doi: 10.3390/jmmp10090336

Authors: Mohd Shahneel Saharudin

Additive manufacturing (AM) has moved beyond prototyping and now produces functional, load-bearing components [...]

Journal of Manufacturing and Materials Processing doi: 10.3390/jmmp10090334

Authors: Alejandro Frechilla Yasser Zekalmi José Antonio Albajez María José Oliveros Sergio Aguado

Surface topography plays a critical role in the functional performance of machined freeform components, yet its assessment traditionally takes place only after manufacturing. This work presents a simulation-assisted framework for predicting the surface topography generated during freeform ball-end milling and using these predictions to support machining-strategy selection. Three finishing strategies (3-axis square, SQ3, 3-axis spiral, SP3, and 5-axis spiral, SP5) were investigated on a representative freeform benchmark by combining high-resolution UVRMAP simulations with experimental topography measurements. Surface signatures were characterized using ISO 25178 areal parameters together with two- and one-dimensional Fast Fourier Transform (FFT) analyses, enabling quantitative evaluation of surface amplitude, preferential orientations, anisotropy, and characteristic spatial periodicities. The results demonstrate that machining strategy and local surface geometry produce distinctive topographical signatures that cannot be fully described by conventional roughness parameters alone.Theproposed UVRMAP methodology accurately reproduces the primary spatial organization of the geometric texture generated by the programmed toolpath, while the incorporation of a controlled non-ideal cutter-edge representation improves the prediction of experimentally observed fine-scale features. The combined experimental–simulation methodology provides a robust framework for comparing and validating the spatial and morphological characteristics of predicted surface topographies, providing a basis for future machining-strategy selection according to application-specific surface requirements.

Journal of Manufacturing and Materials Processing doi: 10.3390/jmmp10090333

Authors: Stoyan Slavov Georgi Valchev Volodymyr Dzyura Pavlo Maruschak Taras Dzhyvak Islam Zakiev

The present research investigates the optimization of ball burnishing (BB) process parameters to create regular lubricating grooves on multilayer connecting rod liners to prevent engine seizure. The study utilized a Taguchi L9 fractional orthogonal array to evaluate the impact of ball diameter, deforming force, and feed rate on the resulting groove widths. Statistical analysis (ANOVA) revealed that ball diameter is the primary driver of groove width variation, exhibiting a non-linear parabolic relationship where the diameter serves as a stabilizing threshold. While deformation force showed a steady linear progression in widening traces, higher feed rates were found to restrict localized plastic flow, resulting in narrower groove widths. For the bimetallic structure (steel back with AlSn20Cu coating), the research recommends tailoring forces to the specific layer—forces for the anti-friction layer and for the substrate to avoid structural destruction. Profilometry confirmed that the height of edge inflows directly correlates with groove depth, ranging from 6 to 30 μm. The optimized non-linear regression model developed in this study achieved an exceptionally high coefficient of determination (R2 = 99.84%), ensuring precise predictive accuracy. Overall, these findings provide a robust framework for researchers to enhance the durability of heavy-duty engine components through controlled surface topography.

Journal of Manufacturing and Materials Processing doi: 10.3390/jmmp10090332

Authors: Xin Chen Kai Cheng Yuanzheng Fu

Optical surface deviations in ophthalmic optics arise from fast tool servo errors, the tool footprint, freeform surface residuals, and the freeform surface curvature responses across processing stages. In this paper, a PAM-Net physics–AI dual-driven compensation control method is presented for addressing the issues in dynamically accurate positioning of a diamond cutting tool via the fast tool servo using existing methods, e.g., struggling to characterize micrometer-scale CNC following-up errors, spatial surface-form perturbations, and S/C optical quality simultaneously. PAM-Net maps Z-axis position, velocity, acceleration, jerk, and A/B-axis phases to surface-form residuals and S/C deviations through tool-lens projection and curvature-mediated optical-response operators, while jointly estimating uncertainty and safety risk for constrained NC compensation. The framework also preserves an interpretable mediation chain from servo dynamics to final optical quality. On holdout-35, removing acceleration/jerk increased RMSE from 0.512 to 5.395 μm, indicating strong predictive dependence on high-order servo dynamics. Closed-loop validation increased the strict ±0.12 D pass rate from 72.5% to 87.5%, alongside reduced surface-form and curvature residuals. These results indicate that learning-based compensation control for high-precision freeform-optics manufacturing requires joint consideration of prediction accuracy, physical interpretability, executable NC write-back, and manufacturing constraints.

Journal of Manufacturing and Materials Processing doi: 10.3390/jmmp10090331

Authors: Kapil Gangwar Mamidala Ramulu

Dissimilar friction stir welding (FSW) of titanium alloys offers a route to spatially optimized aerospace structures, but the asymmetric thermomechanical environment produces heterogeneous microstructures and textures whose interaction with mechanical performance is not well characterized. A near-α/α+β combination of titanium alloys, Ti–6242 SG (advancing side, ADV) and Ti–54M (retreating side, RET), was welded across a matrix of rotation speeds (225–325 rpm) and traverse speeds (100–150 mm·min−1), spanning rotation-to-traverse-speed ratios N/v of 1.80–2.75, which was used throughout as an empirical processing index that orders the conditions of this matrix rather than as a measure of specific heat input. Microstructure, phase identification, relative diffracted-intensity trends, and crystallographic textures were characterized by 2D-XRD at three cross-section locations (ADV, weld nugget center [CEN], RET) and correlated with transverse tensile properties and fracture locations. Partial pole figures were plotted in the simple-shear reference frame with ideal-orientation overlays, intensities in multiples of a random distribution (m.r.d.). The CEN develops the strongest textures, dominated by a basal {002}α component (20–31 m.r.d.) with poles near the normal direction; this concentration lies away from the ideal shear fiber loci and is more readily explained by orientation inheritance during the β→α transformation on cooling than by direct shear, although unambiguous identification of variant selection would require orientation-resolved measurements. The RET develops {101}α and {100}α pole concentrations clustering near the ideal P-fiber loci, consistent with deformation-related texture development, intensifying with both rotation and traverse speed. The ADV shows mixed textures varying non-monotonically with parameters. Two conditions of nearly identical N/v obtained from different parameter combinations (225 rpm/125 mm·min−1 and 275 rpm/150 mm·min−1) nevertheless develop measurably different streak morphologies, microstructures, textures, and tensile responses, showing directly that N/v orders but does not determine the thermomechanical state. Yield strength is uniform (≈900–940 MPa) across the full matrix, consistent with a Schmid-factor estimate in which the basal-near-ND CEN texture gives a very low resolved shear stress on basal systems under transverse loading; joint efficiencies reach ≈90–96%. Ductility, in contrast, tracks consolidation quality rather than texture severity: fracture strain rises almost monotonically with N/v, from ≈0.6–1.4% at N/v ≈ 1.8 (defect-driven, erratic failure) to ≈5.4–6.0% at N/v = 2.60, despite the latter condition carrying the strongest RET pyramidal texture. Full-field strain measurement shows the weld nugget to carry the lowest strain and the highest apparent stiffness of any zone in every condition for which the load record is reliable, with strain accumulating on the advancing side. Consolidated conditions fracture on the advancing side where deformation concentrates, whereas the lowest N/v and longest-exposure conditions fracture in the nugget center; all fracture surfaces are ductile, with the crack path following continuous α layers at prior-β grain boundaries. A favorable processing range within the investigated parameter matrix is N/v ≈ 2.2–2.6, with the best overall combination at 325 rpm and 125 mm·min−1 (N/v = 2.60: UTS ≈ 1010 MPa, ≈5.4–6.0% elongation). Within the parameter range examined here, consolidation quality is the first-order design variable for this dissimilar system, with the zonal texture architecture setting the yield strength level.

Journal of Manufacturing and Materials Processing doi: 10.3390/jmmp10090330

Authors: Ravipudi Venkata Rao Ajinkya Kishor Salve Joao Paulo Davim

Multi-objective optimization has become an indispensable tool for solving engineering design and manufacturing problems involving multiple conflicting objectives. This paper presents a novel parameter-less multi-objective optimization (MOO) framework that combines the strengths of evolutionary MOO techniques with the parameter-free search philosophy of the Jaya and Rao algorithms. The proposed framework incorporates non-dominated sorting, elite archiving, and crowding-distance mechanisms to achieve an effective balance between convergence and diversity while eliminating the need for algorithm-specific control parameters. The proposed framework is first validated on sixteen widely used unconstrained benchmark problems comprising five ZDT, seven DTLZ, two IDTLZ, and two SDTLZ test suites using the maximum number of function evaluations reported in the literature. Its performance is evaluated using five widely accepted quality indicators, namely Generational Distance (GD), Inverted Generational Distance (IGD), Hypervolume (HV), Spacing (SP), and Spread (SD). The benchmark results demonstrate that the proposed framework produces competitive Pareto-optimal fronts and exhibits excellent convergence, diversity, and solution distribution compared with several state-of-the-art evolutionary multi-objective optimization algorithms. The practical applicability of the proposed framework is demonstrated through five representative manufacturing optimization problems involving Selective Laser Melting, Microwave Hybrid Heating, Sustainable Machining, Wire Electrical Discharge Machining, and Wire Arc Additive Manufacturing. These case studies encompass additive, thermal, subtractive, and many-objective manufacturing optimization problems with conflicting performance measures. The generated Pareto-optimal solutions are subsequently ranked using the recently developed BHARAT (Best Holistic Adaptable Ranking of Attributes Technique) multi-attribute decision-making method to identify the most suitable compromise solutions. The obtained results demonstrate that the proposed parameter-less MOO framework provides a simple approach with competitive convergence, diversity, and decision-support capabilities for complex manufacturing optimization problems.

Journal of Manufacturing and Materials Processing doi: 10.3390/jmmp10090329

Authors: Oleh Derkach Andrejs Kovalovs Valerii Kobzar Artem Ratynskyi

An active vibration-based methodology for structural health monitoring of polymer-matrix composites is presented, in which piezoelectric actuators excite resonant vibrations and the diagnostic information is carried by two nonlinear characteristics: the backbone curve and the amplitude-dependent logarithmic decrement. Both are described by a single elastoplastic model of the Iwan (microplasticity) type with a power-law distribution of yield thresholds. The two characteristics share a common power-law exponent, and the model predicts a parameter-free ratio between the modulus defect and the hysteretic intensity. The four parameters are identified by a joint Bayesian fit. The methodology is applied to two carbon-fiber-reinforced polymer objects: a cantilever beam with a symmetric stacking sequence (three modes, 87 to 1431 Hz) and a plate strip with an unsymmetric one (two modes near 34 and 203 Hz), each tested intact and after controlled local damage. The measured ratio reproduces the prediction within 4 to 12%; whereas, the fundamental plate mode reveals a non-frictional, matrix-dominated dissipation. Local damage increases the hysteretic intensity 1.4 to 2.3 times and the modulus defect up to 2.7 times, while the resonant frequency changes by less than 0.8% and the background decrement remains nearly unchanged, giving a compact damage signature with minimal baseline requirements.

Journal of Manufacturing and Materials Processing doi: 10.3390/jmmp10090328

Authors: Himal Sapkota Prateek Neupane Ehsan Mehrdad Hongbing Lu Sangjin Jung

Geometric deviations in unsupported overhang features pose one of the most persistent quality challenges in Laser Powder Bed Fusion (LPBF), where even small deviations from the intended geometry can undermine part functionality and reliability. This study presents a geometrically informed conditional Generative Adversarial Network (cGAN), implemented through the Pix2Pix framework, to predict layer-wise geometric deviations in LPBF-printed parts with overhang geometries, using paired two-dimensional Computer-Aided Design (2D CAD) slices and corresponding X-ray Computed Tomography (XCT)-derived ground truth slices. The study investigates how geometric information can be encoded within the conditional input of the Pix2Pix framework to more effectively guide deviation prediction. A total of 18 models were trained and evaluated across multiple overhang geometry groups and batch size configurations, assessed through a combination of perceptual, structural, and boundary-focused metrics, namely Peak Signal-to-Noise Ratio (PSNR), Structural Similarity Index Measure (SSIM), Learned Perceptual Image Patch Similarity (LPIPS), Fréchet Inception Distance (FID), and Edge Intersection over Union (Edge IoU). The results demonstrated that color-coded inputs consistently improved prediction fidelity, perceptual similarity, and edge alignment relative to their non-color-coded counterparts. Furthermore, a model trained on a balanced multi-geometry dataset showed improved prediction performance on withheld 30° and 60° overhang configurations within the benchmark geometry family. The proposed framework offers a data-driven, design-stage tool for anticipating geometry-dependent deviations in LPBF overhang structures, supporting design for additive manufacturing.

Journal of Manufacturing and Materials Processing doi: 10.3390/jmmp10090327

Authors: Henry Titchener-Hooker Rakan Albarakati Hany Hassanin Khamis Essa

Auxetic polymers offer a route to deformation-activated sealing by transforming axial deformation into lateral expansion, enabling controlled conformity and retention within perforated structures. This paper presents the design-space-guided optimisation of a multi-material polymeric auxetic plug for mechanically activated sealing of circular perforation surrogates relevant to military ground-vehicle structures using a controlled thin-wall surrogate validation framework. The sealing combines an SLA-printed Elastic 50A photopolymer auxetic body with TPU 95A load-transfer and priming components. A parameterised re-entrant unit cell was optimised using response-surface design of experiments coupled with nonlinear finite-element analysis. The optimised geometry, with a height of 6 mm, length of 5 mm, strut thickness of 1.25 mm, and re-entrant angle of 31°, achieved a predicted negative Poisson’s ratio of −2.66 under 20% axial strain. Experimental validation using additively manufactured unit cells confirmed the intended auxetic deformation response. The optimised structure was then integrated into a multi-material plug and tested against a solid polymer benchmark, achieving sealing to approximately 22 kPa with improved anchoring across the tested 22–25 mm perforation range. The results establish a mechanism-driven pathway from polymer auxetic unit-cell optimisation to plug-level pressure-sealing performance, demonstrating the potential of multi-material auxetic architectures as deformation-activated sealing systems for temporary repair of perforated military ground-vehicle structures.

Journal of Manufacturing and Materials Processing doi: 10.3390/jmmp10090326

Authors: Yanjie Du Chuanqi Zhu Chenghui Wu Yuwen Sun

Titanium alloy thin-walled parts are widely used in the aerospace industry because of their excellent high-temperature performance. However, their low structural stiffness and poor machinability often result in substantial machining deformation and severe tool wear, thereby reducing machining accuracy and surface quality. To address these issues, an accurate method is proposed for predicting cutting force and force-induced deformation in the end milling of titanium alloy thin-walled parts while considering tool wear and material removal. First, a cutting force model incorporating tool wear is established to characterize the influence of tool wear on milling forces during titanium alloy machining. Subsequently, a force-induced deformation model is developed based on small-deflection theory to describe the deformation response of the flexible workpiece under milling loads. Furthermore, an iterative strategy is proposed to predict the coupled evolution of cutting force and force-induced deformation during successive material removal. In this strategy, the element stiffness matrix is updated at different feed positions according to the evolving material removal state, while the effects of workpiece deformation on the actual cutting state are incorporated into the cutting force calculation. This provides a framework for accurately predicting cutting force and force-induced deformation. Multilayer end-milling experiments were conducted for validation. The average peak-value errors of Fy and Fz were 7.8% and 5.5% for the new tool and 5.9% and 6.1% for the tool with VB = 0.05 mm, respectively, while the corresponding average deformation prediction errors were 11.8% and 14.5%. These results demonstrate the accuracy of the proposed method.

Journal of Manufacturing and Materials Processing doi: 10.3390/jmmp10090325

Authors: Lapshin V. Petrovich Ilya O. Dudinov

This article studies the problem of modeling the nonlinear characteristics of friction using digital twins for cutting process on metal-cutting machine tools. One of the important characteristics of a mathematical model for the cutting force response to the shaping movements of a cutting tool is the friction coefficient between a cutting tool’s flank wear land and the machined workpiece surface. The dependence of the friction coefficient on the temperature–velocity parameters during cutting is widely known, whereas the mathematical dependences within the general mathematical model for elastic–thermodynamic interaction during cutting have not been determined yet. Therefore, the aim of this study was to create a mathematical model that would reveal the dependence of the friction coefficient between the cutting tool’s flank and the machined workpiece on the temperature of this interaction. To create a model, the authors relied on both the analysis of theoretical studies and the results of a full-scale experiment conducted to determine the actual value of the friction coefficient. By achieving the aim of this study, the authors have refined the general mathematical model for elastic–thermodynamic interaction occurring in the process of cutting on a lathe by taking into account the adhesion–diffusion nature of friction in the contact zone of the cutting tool’s flank and the machined workpiece. Furthermore, the general mathematical model has been validated based on the data obtained in a series of additional experiments using the modern STD.201.1 measuring bench.

Journal of Manufacturing and Materials Processing doi: 10.3390/jmmp10090324

Authors: Chang Gao Xinjie Di Chengning Li

To clarify the effects of restraint conditions on the microstructure and mechanical properties of Gigapascal-grade deposited metal, this study conducted a self-designed weld restraint test using a flux-cored wire designed for Gigapascal-grade deposited metal. Simulation software was employed to calculate the uniform loading restraint intensity at different locations of the weld on the test plates, followed by corresponding welding experiments. Samples were extracted from areas with varying restraint intensities for microstructure characterization and mechanical property testing. The results indicate that as the restraint intensity decreases, the retained austenite content, dislocation density, proportion of low-angle grain boundaries, and kernel average misorientation value in the deposited metal increase, while the grain size progressively refines. As the restraint intensity decreases, the tensile strength and elongation of the deposited metal showed no significant variation. However, the yield strength gradually increased, reaching 978 ± 19 MPa, 1079 ± 24 MPa, and 1141 ± 25 MPa, while the hardness gradually decreased, with values of 433 ± 16 HV10, 371 ± 13 HV10, and 362 ± 10 HV10. The room-temperature impact absorbed energy increased gradually, recorded as 31.2 ± 1.3 J, 38.5 ± 0.9 J and 42.3 ± 1.5 J. Furthermore, the fracture morphology under the restraint intensity of 2.9 × 105 N/mm2 exhibited cleavage facets with river patterns, which are typical characteristics of quasi-cleavage fracture.

Journal of Manufacturing and Materials Processing doi: 10.3390/jmmp10090323

Authors: Andrea M. Rodríguez Mohammad Keshmiri Sajid U. Butt Brian A. Fleck Ahmed J. Qureshi

Infrared thermography is a well-established non-contact technique for surface temperature monitoring across diverse manufacturing and materials processing applications, such as thermal process monitoring, quality inspection, and high-temperature material evaluation; however, its measurement accuracy is affected by emissivity variations in multi-material environments, which distort the relationship between apparent radiometric temperature and true surface temperature. This study presents a sequential thermal correction framework to improve surface temperature estimation in heterogeneous material systems under normal viewing conditions (90° incidence angle). The methodology operates in two stages: first, apparent emissivity is predicted from infrared temperature and material-specific features using regression-based models; second, the estimated emissivity is incorporated into the temperature-correction model to estimate the reference surface temperature, validated against K-type thermocouple measurements. Controlled experiments were conducted on A36 structural steel and alumina ceramic specimens, representing multi-material combinations found in manufacturing environments, over approximately 20 °C to 700 °C. Synchronized thermal imaging and thermocouple data were acquired throughout heating. Polynomial regression and machine learning approaches were evaluated using leave-one-session-out validation. The framework achieved an out-of-session mean absolute error of 9.45 °C, supporting reliable thermal monitoring in manufacturing applications.

Journal of Manufacturing and Materials Processing doi: 10.3390/jmmp10090322

Authors: Tingting Wang Pengkai Wang Yang Yang Gang Yao Xuran Liu Gang Liu Kai Xu

This study quantitatively characterized the corrosion morphology evolution of Q355B steel under magnetic fields (MFs) using non-contact 3D scanning. MFs exert a threshold-dependent effect on the corrosion morphology and spatial distribution of Q355B steel; while the macroscopic mass loss rate remains largely stable across different MF intensities, the maximum local pit depth peaks at 60 mT, increasing by 42.9%. Spatial autocorrelation shifts from longitudinal long-range to enhanced transverse continuity. Depth distributions follow log-normal distributions. Under uplift, corroded helical anchor bearing capacity varies nonlinearly with MF intensity, reaching a maximum at 30 mT due to the optimal synergy between enhanced surface roughness-induced interface friction and localized cross-sectional reduction. These findings support corrosion assessment and mechanical prediction for Q355B components in MF-coupled environments.

Journal of Manufacturing and Materials Processing doi: 10.3390/jmmp10090321

Authors: Yifan Yu Shuxi Chen Liting Lei Depeng Gao Jianlin Qiu

Rolling element bearings are critical components in rotating machinery, yet assessing and predicting their reliability under heavy industrial noise remains challenging. Existing methods suffer from three major limitations: (1) single-channel signal processing and single-scale indicators lack robustness against non-stationary noise; (2) classical multi-channel decomposition methods, such as multivariate variational mode decomposition (MVMD), rely on empirical parameter tuning, which frequently leads to over- or under-decomposition; and (3) monolithic deep architectures and homogeneous ensemble models suffer from prediction drift and generalization bottlenecks during long-term temporal extrapolation. To address these issues, this paper introduces an automated framework that combines adaptive multi-channel signal purification with a heterogeneous stacking ensemble (HeteroStack-LR). Unlike conventional MVMD pipelines that fix [K,α] empirically, the Sequoia Optimization Algorithm (SOA) autonomously determines the globally optimal configuration, achieving a mean SNR of −2.08dB—a 1.88 to 2.50dB improvement over standard VMD/MVMD baselines—along with up to a 37.1% reduction in computation time. Rather than relying on conventional single-metric intrinsic mode function (IMF) selection, we construct a multi-domain hybrid index integrating the Fault Correlation Factor, energy ratio, and refined composite multiscale dispersion entropy (RCMDE) to robustly identify noise-resistant components, thereby enhancing denoising quality by 22.4% to 32.2% over single-scale criteria. Furthermore, contrasting with linear PCA-based reduction, Diffusive Topology Neighbor Embedding (D-TNE) effectively preserves the nonlinear manifold structure of degradation trajectories in a low-dimensional space. Finally, a heterogeneous stacked ensemble featuring an out-of-fold (OOF) leakage-prevention strategy and a logistic regression meta-learner is designed to suppress prediction drift while avoiding the over-parameterization typical of deep architectures. Experimental results across four bearing datasets demonstrate that HeteroStack-LR achieves a minimal MAE of 0.063 with a variance of ≤±0.002, outperforming state-of-the-art deep architectures (such as TCN, CNN-LSTM, BiLSTM-Attention, and Transformer) as well as classical baselines (Bi-LSTM, CNN, and LSSVM). Ablation studies confirm that removing SOA and MVMD degrades MAE by 12.7% and 19.0%, respectively, validating that the framework’s strength stems not from any isolated module, but from the end-to-end synergistic integration of signal purification and reliability prediction.

Journal of Manufacturing and Materials Processing doi: 10.3390/jmmp10090320

Authors: Jie Ren Peng Zhang Zhenqiang Zhang

Silicon carbide is a typical hard and brittle semiconductor material that is prone to high cutting resistance, surface defects, and subsurface damage during nanomachining. To reveal the atomic-scale material removal mechanism of 3C-SiC under low-power laser heating, a molecular dynamics model of single-crystal 3C-SiC cut by a diamond tool was established, and conventional cutting was compared with laser-assisted cutting. Under low-power laser irradiation, the evolution of system potential energy was generally similar to that observed in conventional cutting, indicating limited overall thermal disturbance. The average cutting force decreased from approximately 285 nN to 275 nN, while the maximum burr height was reduced by about 0.75 Å. In contrast, the chip pile-up height increased by approximately 1.68 Å, and the temperature under laser-assisted cutting was slightly higher than that under conventional cutting. The results indicate that moderate laser-induced thermal effects enhance atomic migration in the cutting region, reduce the resistance to material removal, and improve the flatness and edge quality of the machined surface. These findings provide theoretical insight into the mechanisms of the laser-assisted nanomachining of 3C-SiC.

Journal of Manufacturing and Materials Processing doi: 10.3390/jmmp10090319

Authors: Tugdual Amaury Marie Le Néel Mint Abat Ahmed El Hadi Philippe Feraud Matthieu Rauch

Metal additive manufacturing based on Fused Filament Fabrication (FFF) of metal-filled polymers is emerging as a cost-effective alternative to conventional processes such as Metal Injection Molding (MIM), but its industrial relevance remains limited by challenges in densification and mechanical performance. This study presents an exploratory investigation of a low-cost FFF process using 316L stainless steel filament for industrial applications in railway maintenance. A Taguchi L8 design was employed as a screening approach to evaluate the influence of key printing parameters, followed by sintering using both internal and external configurations. The mechanical response depended strongly on sintering temperature: sintering at 1350 °C increased the ultimate tensile strength to 216–278 MPa and Young’s modulus to 63–109 GPa, while the apparent porosity remained between 12.6% and 16.9%. In the exploratory main-effects analysis of variance (ANOVA), none of the investigated printing parameters had a statistically significant effect on the measured responses (p > 0.05). For porosity at 1350 °C, nozzle diameter nevertheless showed the largest descriptive contribution (23.81%, F = 2.06, p = 0.2241). Overall, porosity introduced during the printing stage remained a major limitation of the process. Although the achieved properties remain below those of conventionally processed 316L, the process demonstrates potential for non-structural and cost-sensitive applications. Because each factor combination was tested once, the ANOVA and signal-to-noise (S/N) results are interpreted as exploratory screening and response ranking rather than confirmatory inference or independent evidence of robustness.

Journal of Manufacturing and Materials Processing doi: 10.3390/jmmp10090318

Authors: Leonardo Pellin Rigon Adonis Pellin Richard Thomas Lermen Cristiano José Scheuer Rafael Luciano Dalcin

Medium-carbon steels are susceptible to heat-affected zone (HAZ) hardening during welding. This study evaluated the effects of preheating temperature and joint geometry on mechanized gas metal arc welded (GMAW) joints in 6.3 mm thick SAE 1045 steel. Butt and fillet joints were welded under conventional single-pass conditions from room temperature to 250 °C, while an additional two-pass procedure was evaluated separately. Metallography and hardness were evaluated for both joint geometries, whereas tensile and Charpy V-notch tests were performed only on butt joints. Significant joint geometry × preheating condition interactions were identified for weld metal (WM) area, HAZ area, WM hardness and HAZ hardness. Average HAZ hardness remained below 300 HV10 for all conventional single-pass conditions. Among the butt joint single-pass conditions, no statistically significant effect of preheating was detected for ultimate tensile strength (UTS) or Charpy absorbed energy, and all tensile specimens fractured in the base metal (BM). The two-pass procedure was treated descriptively because the second deposition simultaneously altered multiple welding variables. Overall, the effects of preheating on WM and HAZ areas and hardness were joint-geometry-dependent under the investigated conditions.

Journal of Manufacturing and Materials Processing doi: 10.3390/jmmp10090317

Authors: Kirill O. Akimov Konstantin V. Ivanov Andrey I. Dmitriev

The investigation of structure and properties in the intermetallic compound Ni3Al, synthesized via self-propagating high-temperature synthesis (SHS-compaction) under quasi-volumetric thermal-explosion conditions, is presented in this study. The effect of preliminary pressure gradient in the range of 33–136 MPa on the quantitative properties of the final microstructure has been identified. It was demonstrated that a preliminary pressure of 115 MPa suppresses secondary recrystallization via grain boundary pinning by Al2O3 particles, which halves the average grain size to 7–11 μm. Consequently, a pronounced room-temperature yield strength enhancement was documented, following the grain boundary strengthening mechanism. High-temperature testing up to 1000 °C revealed an anomalous yield strength peak attributable to the activation of Kear–Wilsdorf barriers. A comprehensive fractography analysis shows a profound transition from intergranular brittle fracture to a mixed mechanism featuring dimple rupture at extreme temperatures. This work illustrates SHS-compaction as a highly efficient powder metallurgy approach for synthesizing structural intermetallics.

Journal of Manufacturing and Materials Processing doi: 10.3390/jmmp10090316

Authors: Christoph Zachert Markus Meurer Thomas Bergs

Fir-tree slots provide the form-fit connection between turbine disks and blades in aerospace engines and therefore constitute highly stressed geometries in safety-critical components. These slots are manufactured by broaching, a machining process performed near the end of the manufacturing chain for turbine disks made from high-strength materials such as Inconel 718. The severe thermo-mechanical loads encountered during broaching result in pronounced wear of high-speed steel tools, potentially leading to cutting-edge chipping and, consequently, compromising component quality. Early and reliable detection of tool defects is therefore essential to ensure process stability and component quality. In this study, a data-driven process monitoring system based on internal machine signals was used to investigate the detectability of cutting-edge chipping of broaching tools with straight cutting edges, identifying relevant signal sources and features and evaluating different modeling approaches. Broaching experiments with intentionally induced defects were conducted, and features in the time and frequency domains were extracted from torque, current, and three-phase motor signals. These features were used to train and compare a support vector machine, a random forest, and a neural network. The results demonstrate that reliable classification is feasible, with the neural network and support vector machine achieving balanced accuracies of up to 98.96% and 99.13%, respectively. High-frequency motor signals showed the highest relevance, highlighting their potential for industrial applications.

Journal of Manufacturing and Materials Processing doi: 10.3390/jmmp10090315

Authors: Chun Kang Yufa Deng Mingji Huang Hongzou Chao Jinsong Liu Guangming Chen Tianle Liu Tingshu Chen

In this study, the hydrogen embrittlement (HE) susceptibility and hydrogen-induced cracking behavior of X70 pipeline steel were investigated in CH4–H2 mixed-gas environments containing 5–20% H2 at a total pressure of 7 MPa. Slow strain rate tensile tests, thermal desorption spectroscopy, fractography, and electron backscatter diffraction (EBSD) were employed to correlate hydrogen uptake, mechanical degradation, fracture morphology, and crack evolution. The results showed that increasing the hydrogen fraction progressively deteriorated the mechanical performance of X70 pipeline steel, as evidenced by reductions in tensile strength and elongation. This degradation was accompanied by a fracture-mode transition from micro-void coalescence to quasi-cleavage fracture. More importantly, EBSD analysis revealed a hydrogen-content-dependent change in the role of the heterogeneous microstructure. At relatively low hydrogen fractions, fine-grained regions and microstructural heterogeneity acted as effective barriers to hydrogen-induced crack propagation. However, at higher hydrogen fractions, this intrinsic crack-arresting capability was substantially weakened. Newly formed cracks were observed to initiate ahead of pre-existing cracks and propagate preferentially along grain boundaries, with limited local plastic deformation. These findings demonstrate that the increased HE susceptibility of X70 pipeline steel under high-H2 mixed-gas conditions is associated with the progressive loss of the crack-arresting resistance provided by its heterogeneous microstructure.