Search Results (6,038)

This review paper presents a comprehensive and system-oriented analysis of advanced non-destructive testing (NDT) technologies for metal additive manufacturing (AM), including X-ray computed tomography (XCT), ultrasonic testing (UT), infrared thermography, acoustic emission (AE), and electromagnetic techniques. While the existing literature often focuses on the physical principles of individual NDT methods, this work addresses a critical knowledge gap by analyzing NDT as a digitally integrated “quality intelligence layer” rather than a standalone post-process inspection tool. The primary motivation is to bridge the disconnect between raw inspection data and cyber–physical production systems. Particular focus is given to NDT data analytics and digitalization, where machine learning (ML) and digital twin (DT) integration are discussed as fundamental enablers of intelligent manufacturing. The review systematically examines image and signal processing pipelines required for quantitative defect characterization, highlighting challenges related to voxel resolution, signal-to-noise ratio, anisotropic microstructures, and operator dependency. It further analyzes supervised learning, deep learning, and multi-sensor data fusion approaches for automated defect classification and predictive quality assessment. Furthermore, the role of digital twins in coupling in situ monitoring data, ex situ NDT results, and physics-based models is discussed as a transformative pathway toward closed-loop process control and evidence-based certification. By synthesizing NDT science with digital manufacturing architectures, this review contributes a unique framework for transitioning from traditional inspection-centric quality control to a predictive, adaptive, and digital twin-enabled quality assurance paradigm. The work concludes by identifying key research gaps in data standardization and computational scalability, providing a strategic roadmap for the future of smart AM production. Full article

The rapid growth of global air traffic places the aviation industry under dual pressure: meeting increasing demand for aircraft while substantially reducing life-cycle environmental impacts. As advancements in aerodynamics, propulsion, and the adoption of lightweight composite materials continue to reduce operational fuel burn, the relative significance of manufacturing and End-of-Life phases is expected to increase. This study develops a low-fidelity aerostructural optimization framework for high aspect ratio wings that integrates life-cycle considerations into early-stage material selection. Using aluminum and carbon fiber reinforced polymers (CFRP) as reference materials, the framework quantifies trade-offs in mass savings, fuel burn, and CO₂ equivalent emissions across production, operations, and disposal phases. Results show that while CFRP offers substantial benefits in structural efficiency and operational emissions, aluminum performs more favorably in End-of-Life scenarios due to its high recyclability. The study further evaluates the potential of Sustainable Aviation Fuel (SAF) blending as a complementary decarbonization lever, revealing that moderate SAF adoption can offset part of the operational advantage of CFRP. Overall, this work demonstrates the importance of coupling material choice with life-cycle assessment in aerostructural design and outlines a pathway toward multi-objective optimization frameworks that balance performance with environmental sustainability. Full article

Sustainable production in dental and orthodontic 3D printing has gained increasing attention due to environmental concerns and the need for cost-effective and resource-saving solutions. This study presents a proof of concept for using recycled polymers and fused granular fabrication (FGF) in a closed-loop 3D printing approach, omitting intermediate filament manufacturing. A desktop 3D printer served as the kinematic platform and was modified with a pellet-based extruder to directly process recycled polyethylene terephthalate glycol (PETG) flakes, obtained by shredding previously printed PETG parts, into dental models. Dimensional accuracy was evaluated using optical 3D scanning analysis. The results indicate that models produced from recycled PETG are, in principle, suitable for dental and orthodontic applications within the investigated scope. This technical note provides initial evidence supporting the integration of recycled thermoplastics into dental and orthodontic model fabrication as part of sustainable additive manufacturing workflows. Potential pathways for workflow integration in clinical and laboratory environments, as well as directions for future research, are outlined, including the optimization of printing parameters and process stability. The main technical challenges were unreliable feedstock flow, causing bridging and jamming, while thermal creep from insufficient inlet cooling promoted premature softening of the flakes, causing torque spikes and unstable feeding. Full article

Metal additive manufacturing (AM) has progressed from prototyping toward industrial deployment, yet adoption remains uneven because many initiatives are still driven by isolated process demonstrations rather than system-level manufacturing strategy. This framework review proposes a gated decision workflow for integrating metal AM into industrial systems by coupling process-family selection and route definition, Design for Additive Manufacturing (DfAM) and sustainability considerations. The paper consolidates a comparative matrix of six metal AM process families for early down-selection, introduces a minimal evidence checklist linking each decision gate to required artifacts, and contextualizes the workflow through representative part archetypes. The framework is further supported by practical guidance on process-specific DfAM constraints, including support strategy, residual stress, and surface integrity in powder bed fusion; shrinkage-driven design in sinter-based routes; and machining allowances in repair and hybrid manufacturing. Rather than positioning metal AM as a universal substitute for conventional manufacturing, this work defines it as a complementary, strategy-dependent enabler whose sustainability benefits depend on system-level integration and application context. Full article

This study investigates the mechanical behaviour of continuous carbon-fibre-reinforced additively manufactured composite structures aimed at applications in aeronautical structures, through a combination of experimental testing and numerical simulation. Tensile, compressive, and shear tests established stiffness and failure characteristics, while finite element analyses were used for a preliminary calibration-based reproduction of the measured coupon response, with an emphasis on the initial elastic part of the impact event. The integration of measured data with structural modelling provides a clearer understanding of load transfer and damage initiation in continuous-fibre AM, supporting more accurate simulation-based design of additively manufactured composite components. Experimental results show pronounced anisotropy, and a stable, rate-dependent impact response. The preliminary numerical model based on CT-derived homogenized properties accurately reproduces the initial part of the measured quasi-static and dynamic responses. Full article

This study investigates the influence of specific heat input and weld configuration on heat affected zone hardness and residual stress of S960MC high strength steel welds. In total, five types of weld samples were manufactured by Tungsten Inert Gas (TIG) autogenous welding and Metal Active Gas (MAG) butt welding to simulate the effect of increasing heat input and constraining the relative motion of welded parts during the heating and cooling phase. The obtained results show that the highest axial tensile residual stresses with magnitude above 900 MPa, combined with a hardness drop in a range from 13 up to 18%, occur mostly in the sub-critical heat affected zone, making it the critical zone of the weld. Increasing the heat input during welding does not have a simple correlation with generating more residual stresses and the trends obtained on the surface are different from results evaluated at a depth of 0.2 mm. Restraining the relative part motion during the welding affects mostly the tangential residual stresses, causing an increase in their tensile magnitude localized in the middle of the heat-affected zone while almost no influence on the axial residual stress component was recorded. Full article

Modern requirements for highly critical threads, such as drilling tool-joint threads or trapezoidal threads of heavy machine tools, impose requirements for high accuracy and at the same time wear resistance of thread cutters. Conventional thread cutters available on the global market have a profile that coincides with the thread profile. Their rake angle and the angle of inclination of the cutting edge are typically zero. However, to ensure long tool life and high cutting performance, such tools should have optimal values of the geometric parameters of the cutting part, particularly the rake angle and the inclination angle of the cutting edge. Non-zero values of these angles distort the thread profile, and there are currently no established algorithms for profiling such cutters. This analytical study aims to develop an algorithm that enables the straightforward manufacture of high-performance and at high-precision thread cutters with interpolated straight sides profile flanks for producing trapezoidal, triangular and buttress threads, including those made of difficult-to-machine materials. The obtained analytical expressions accurately describe the cutting edge of such cutters as a hyperbola, functionally dependent on geometric parameters such as pitch, diameter and thread profile angle, as well as on the rake angle and the inclination angle of the cutting edge. To simplify manufacturing, methods of rectilinear approximation of the curvilinear profile are proposed. The validity of such a replacement has been theoretically confirmed, as the maximum deviation of the hyperbolic profile from the linear approximation does not exceed 2 micrometers. The results indicate no significant deviations in the profile angle of the cutters with relatively large rake and inclination angles (γ = 10° and λ = 7°). Deviations from the nominal profile angle of the trapezoidal thread profile angle of 15° do not exceed 0.1°, while for tool-joint threads (30°), they range from 0.01° to 0.09°. However, significant deviations in the profile (up to 0.49°) occur in the case of machining buttress threads with a profile of 7°/45°. Experimental verification on a lathe confirms the theoretical results. Full article

This article addresses the lack of repeatability and reproducibility that has inhibited the widespread adoption of Laser Powder Bed Fusion Additive Manufacturing (PBF-LB/M) for service-critical part fabrication in production. A rigorous analysis of critical dimensional variations at a statistically significant scale is essential to understand the influence of process co-factors in PBF-LB/M, serving as a vital step toward process control. Structured white-light profilometry provides an effective balance of capability and features for performing such analysis, including advanced focus variation-based feature extraction. In this work, two types of samples were fabricated, each having either thin gaps or thin walls of varying widths ranging from 200 to 1000 µm. Samples containing these features were designed with and without a constraining base geometry and built along different orientations across various locations on the build plate in two layer thicknesses: 30 µm and 60 µm. Co-factors such as base geometry, specimen orientation, layer thickness, and location on the build plate were investigated for their impact on measurement variations in the as-built condition. The achievable resolution and repeatability was found to be 500 μm, and thus did not conform to the machine manufacturer’s stated minimum of 150 μm. The presence of a base geometry effectively reduced the variations preferentially for features larger than this limit. Features smaller than 500 µm exhibited a variation of approximately 1.5–3 times the D50 size of the powder feedstock, regardless of the co-factors. The tightest control over the variations was observed to occur at the center of the build plate. This study aims to quantify the combined effect of multiple process co-factors on the repeatable dimensional process capability of sub-millimeter PBF-LB/M features in Ti6Al4V. Full article

Additive manufacturing (AM) has revolutionized industrial production. However, the repair of AM components remains a critical challenge due to their unique microstructural features. While repair approaches for conventionally manufactured alloys are well established, their direct transferability to AM parts remains largely unexplored due to the unique thermal history and anisotropic microstructure of additive components. This study investigates a novel repair and improvement strategy for Powder Bed Fusion–Laser Beam/Metal (PBF-LB/M)-fabricated AlSi10Mg components, combining Electrospark Deposition (ESD) for dimensional restoration with subsequent Ultrasonic Peening Treatment (UPT) for surface enhancement. Microstructure, porosity, surface roughness, hardness profiles, residual stresses, and corrosion behaviour were systematically characterized using SEM, optical microscopy, profilometry, Vickers microhardness testing, XRD, and electrochemical polarization tests. The results show that the ESD process is capable of producing coatings with excellent interfacial adhesion to the substrate, with an initial porosity of 3.6 ± 0.5%. The subsequent UPT induces a significant densification effect on the deposited material, reducing porosity by approximately 50% and increasing surface hardness by up to 48% in the upper region of the coating. Furthermore, XRD analysis reveals that UPT completely reverses the residual stress state from tensile (typical of the ESD process) to compressive in all measured directions, thereby improving the overall structural integrity. Ultimately, the combined ESD + UPT alters the electrochemical response of AlSi10Mg deposits, resulting in a nobler corrosion potential, albeit with a slightly higher corrosion current density. Full article

Medical device manufacturing requires strict quality control, reliable traceability, and compliance with regulatory requirements. In many cases, inspection activities are still carried out manually and production information is recorded separately, which can result in inconsistent defect detection and limited visibility of manufacturing performance. This paper presents the development and industrial implementation of an integrated closed-loop quality control architecture for a sterile single-use medical device assembly line, addressing the lack of integration between inspection, traceability, and control systems in existing manufacturing approaches. In the proposed approach, we combine radio-frequency identification, machine vision inspection, programmable logic control, and centralized production monitoring. RFID tags store the status of each unit at individual stations so that defective products cannot proceed to downstream operations. Machine vision systems verify component presence, detect missing parts, and confirm color-specific assembly requirements during production. The architecture was tested through implementation on an assembly line and evaluated with comparative pilot studies against a traditional manual inspection process. The upgraded line achieved scrap cost reductions of 52.77% and 53.23% while also improving inspection consistency and production traceability. The results demonstrate that integrating machine vision inspection with RFID traceability can significantly improve quality control and manufacturing efficiency in regulated medical device production. Full article

The use of parts made of polymeric materials has occasionally highlighted the need for them to possess the best possible mechanical properties. One of the currently widely used processes for manufacturing parts from polymeric materials is fused deposition modeling. This process allows for variations in the magnitudes defining the mechanical properties of polymeric materials to be obtained through an appropriate selection of the process input factor values. The analysis of the process has highlighted the primary factors capable of affecting the values of parameters corresponding to the mechanical properties of polymeric materials. The opinions formulated by various researchers regarding the influence of fused deposition modeling application conditions on some of the mechanical properties of polymeric materials have been synthetically and systematically presented. In terms of mechanical properties, tensile strength, compression strength, elongation at break, flexural strength, torsional strength, impact strength, fatigue resistance, and hardness were taken into consideration. Some modeling and optimization solutions for the influence exerted by the 3D printing process input factors on the values of the parameters defining the mechanical properties of polymeric materials in parts manufactured via the FDM process were also highlighted. Full article

Reducing the ecological footprint of aviation is a key objective in the development of future aircraft. This is particularly relevant in the emerging field of Urban Air Mobility, which demands sustainable yet industrially feasible solutions due to expected high production rates. As part of the cooperative research project KONKAV, innovative materials and manufacturing methods are being explored to meet these demands. One such approach is the partial consolidation of nonwovens made from recycled carbon fibers, aimed at producing multifunctional, recyclable components for Urban Air Mobility cabin linings for high bending stiffness requirements. This study presents the experimental characterization of various nonwoven architectures, focusing on how different levels of consolidation affect their specific mechanical properties. The partially consolidated structure enables tailored stiffness profiles, making it possible to optimize structural performance while integrating functions such as thermal insulation and acoustic damping directly into the lining. An analytical material model has been developed by analyzing the experimental results. The findings demonstrate that partially consolidated nonwovens can achieve a competitive stiffness-to-weight ratio, with advantages over conventional glass-fiber-reinforced composites in terms of eco-efficiency and circularity. The proposed construction method offers potential for cost-effective, lightweight solutions that support closed-loop material use in aviation interiors. Full article

In response to the growing demand for sustainable manufacturing, 3D printing using recycled polyethylene terephthalate (rPET) offers a novel waste-to-value conversion method. Although the application of rPET in additive manufacturing has attracted significant attention from both the academic and industrial sectors, substantial challenges impede its further development, notably the high processing shrinkage and poor mechanical properties of the final product. This study focuses on developing recycled PET-based composites with favorable processing, thermal, and mechanical properties. Regranulates were produced via twin-screw extrusion using PET flakes, multifunctional chain extenders, and short glass fibers (GFs). The rPET-GF composites were characterized in terms of their processing, thermal, thermomechanical, and mechanical properties. Epoxy-functional chain extender modification effectively increased the molecular weight and improved the processability, whereas GF reinforcement enhanced the tensile properties of both injection-molded and FDM-manufactured parts. A primary advantage of the rPET systems developed in this study is their delayed crystallization kinetics. These findings highlight the significant potential of the composites developed herein for extrusion-based additive manufacturing (MEX-AM), as delayed crystallization facilitates enhanced interfacial adhesion, lower volumetric shrinkage, and superior dimensional stability. Full article

The demands of competitiveness in global markets require the integration of Industry 4.0 (I4.0) digital technologies for any manufacturing company, regardless of size. Industrial operations require complete supply chain visibility to ensure data protection and authenticity throughout the process. This document presents a distributed architecture based on RAMI 4.0, designed for product traceability in industrial environments. It integrates automation tools, IIoT communication, cloud storage, artificial intelligence, and secure data transmission using encrypted communication protocols. The system consists of a hybrid architecture; only the first, lower-level layer corresponds to a simulated manufacturing plant with deterministic and stochastic dynamics within the production line. In the second part, the middle and upper layers are implemented, where plant data is transmitted to a cloud instance, stored in a PostgreSQL database, and subsequently analyzed using automated scripts. Reporting capabilities are incorporated with ChatGPT-3.5 Turbo, and visualization is provided through Odoo. Experimental tests demonstrated an average end-to-end communication latency of less than 200 ms, a packet loss rate of 2.67%, and 100% reliability in verifying requested reports when using the cognitive computing service. Furthermore, the results of the systematic vulnerability identification process for the architecture show a significant reduction in overall risk for most assets, with a predominant shift from high or moderate to low or moderate. The proposed architecture is validated in a simulated industrial environment under controlled conditions, demonstrating its viability as a prototype rather than as a fully implemented industrial solution. Full article

Unsupported and weakly supported overhang features remain a critical challenge in laser powder bed fusion (LPBF) due to their strong susceptibility to geometric degradation, residual stress accumulation, and part distortion. In this study, bridge-shaped structures with four different arch sizes are fabricated to systematically investigate geometry-dependent macroscopic forming quality, stress evolution, and distortion behavior. Experimental results show that increasing arch size leads to progressive thickness reduction at the arch bottom and eventual overhang closure loss, indicating a monotonic deterioration in geometric fidelity. A thermo-mechanically coupled finite element model is developed and calibrated using 3D scanning measurements of warpage, achieving a maximum deviation below 0.03 mm between predicted and measured displacements. Numerical analyses reveal that larger arch sizes promote local heat accumulation and reduced cooling rates beneath the arch, which reduce the instantaneous load-bearing capacity of the material and increase its susceptibility to downward deformation. Meanwhile, arch size significantly influences the establishment of structural continuity and stress transfer during printing; incomplete closure in large arches interrupts load-bearing paths and alters stress redistribution at intermediate stages, whereas similar stress evolution trends are observed once geometric continuity is achieved. These findings demonstrate that arch closure acts as a key structural transition controlling stress transmission and distortion development during LPBF, thereby providing mechanistic insight into geometry-induced defects and offering quantitative guidance for the design of unsupported features in additively manufactured components. Full article