Search Results (68)

The micro-geometry of the cutting edge plays a crucial role in material flow ahead of the cutting edge and chip formation, primarily influencing chip formation mechanisms and the minimum cutting thickness. In the context of turning 304 stainless steel, however, existing research still lacks a unified quantitative framework linking “cutting edge micro-geometry—material separation behavior (separation point/minimum uncut chip thickness)—microstructural evolution of the machined surface.” This gap hampers mechanistic optimization design aimed at enhancing machining quality. This study examines the turning of 304 stainless steel by integrating analytical modeling, finite element simulation, and experimental validation to develop a predictive model for minimum cutting thickness. It analyzes the effects of tool nose radius and asymmetric edge morphology, and a microstructure evolution prediction subroutine is developed based on dislocation density theory. The results indicate that the minimum cutting thickness exhibits a positive correlation with the tool nose radius, and their ratio remains stable within the range of 0.25 to 0.30. Under asymmetric edge conditions, the minimum cutting thickness initially increases and then decreases as the K-factor varies. The developed subroutine, based on the dislocation density model, enables accurate prediction of dislocation density, grain size, and microhardness in the machined surface layer. Among the factors considered, the tool nose radius demonstrates the most pronounced influence on microstructure evolution. This research provides theoretical support and a technical reference for optimizing cutting-edge design and enhancing the machining quality of 304 stainless steel. Full article

This paper investigates the influence of design parameters on fluid leakage in axial piston pumps. Particular emphasis is placed on the analysis of operating clearances, sealing surfaces, and geometric relationships that affect volumetric efficiency and system reliability. Through a systematic review of 32 relevant sources, key components contributing to both internal and external leakage are identified, along with approaches for their optimization through material selection, microgeometry, tolerances, and thermodynamic conditions. Modern methods for diagnostics and leakage prediction are also considered, including the application of artificial intelligence and numerical simulations. The findings of this review may serve as a basis for improving the design and maintenance of axial pumps, with the aim of increasing efficiency and reducing losses. Full article

In the modern automotive industry, one of the most challenging tasks is minimizing energy losses caused by friction. Despite its significance, only a limited number of numerical simulation tools are available for effectively addressing lubrication-related problems. The accurate modeling of lubrication phenomena requires solving a specialized form of the Navier–Stokes equations, which accounts for cavitation effects within a thin fluid film. To address this, a finite element software is currently under development to solve the Reynolds equation while incorporating cavitation effect. This advanced tool enables the precise simulation of how the microgeometry of contacting surfaces influences the lubrication characteristics of the fluid film. By optimizing these surface features, the research aims not only to reduce energy dissipation but also to ensure the long-term durability of mechanical components. The findings obtained thus far demonstrate promising improvements in lubrication efficiency and structural longevity. These results, along with the methodological advancements, will be presented in detail at the upcoming conference. Full article

This paper investigates the influence of substrate grain size on the behavior of a multilayer CrN/CrAlN coating, with the bilayer thickness varying across the cross-section in the range of 200–1000 nm. The substrate tools were made of WC-Co sintered carbide with three different grain sizes. The coatings were subjected to mechanical and tribological tests to assess their performance, including nanohardness, scratch resistance, and tribological testing. The coating’s roughness was measured using a 2D profilometer. Additionally, the chemical composition and surface morphology were analyzed using Scanning Electron Microscopy (SEM) and Energy Dispersive X-Ray Spectroscopy (EDX). The durability tests were performed on an industrial CNC machine tool on the particleboard. The results revealed that tools with ultra-fine nano-grain (S) and micro-grain (T) WC-Co substrates exhibited a significant increase in tool durability by 28% and 44%, respectively. Significant differences in the microgeometry of the substrate U, especially in relation to the tool based on substrate S, explain the lack of improvement in its durability despite the use of a multilayer coating. Full article

Non-contact, non-destructive testing of surface microgeometry plays a key role in such industries as microelectronics, additive manufacturing, and precision engineering. This paper presents the development and experimental testing of a digital holographic system based on a low-coherence laser diode operating at two close wavelengths, designed to measure height differences in the micrometer range. The method is based on a Michelson interferometer and reconstruction of the complex amplitude of the object wave, which allows phase measurements with subsequent phase conversion into heights. The tests were carried out on micrometer roughness standards with a trapezoidal profile with a groove depth from 24.5 μm to 100 μm and a profile width from 65 μm to 150 μm, as well as on reference strokes with a width from 25 to 200 μm. The obtained data demonstrate the possibility of three-dimensional and two-dimensional visualization of the objects under study with a relative error in height from 5.3% to 11.6% and in width up to 18.6%. It is shown that the system allows reliable measurement of defects of metal surfaces in the range from 25 to 100 μm both vertically and horizontally. Thus, the developed method can be used for high-precision, non-destructive testing in a wide range of technological tasks. Full article

Gear whine noise is governed not only by intentional microgeometry modifications but also by unavoidable pitch (indexing) deviation. This study presents a workflow that couples a tooth-resolved surface scan with a calibrated pitch-deviation table, both imported into a multibody dynamics (MBD) model built in MSC Adams View. Three operating scenarios were evaluated—ideal geometry, measured microgeometry without pitch error, and measured microgeometry with pitch error—at a nominal speed of 1000 r min⁻¹. Time domain analysis shows that integrating the pitch table increases the mean transmission error (TE) by almost an order of magnitude and introduces a distinct 16.66 Hz shaft order tone. When the measured tooth topologies are added, peak-to-peak TE nearly doubles, revealing a non-linear interaction between spacing deviation and local flank shape. Frequency domain results reproduce the expected mesh-frequency side bands, validating the mapping of the pitch table into the solver. The combined method therefore provides a more faithful digital twin for predicting tonal noise and demonstrates why indexing tolerances must be considered alongside profile relief during gear design optimization. Full article

Background/Objectives: Accurate implant impressions are critical for capturing the three-dimensional (3D) spatial positioning of implants. Digital workflows using intraoral scanners (IOSs) and scan bodies offer distinct advantages over conventional elastomeric techniques. However, the geometry of scan bodies may influence the precision and trueness of IOS-acquired data, and optimal design parameters remain undefined. This systematic review aims to evaluate the effects of scan body geometry on the trueness of digital implant impressions captured using IOSs. Methods: A systematic search was conducted across PubMed, Scopus, EMBASE, Web of Science, the Cochrane Library, and Google Scholar up to 25 February 2025. Eligible studies assessed the impact of scan body geometry on the accuracy of implant-level impressions acquired with IOSs. Study quality was assessed using the Quality Assessment Tool for In Vitro Studies of Dental Materials (QUIN). Results: Twenty-eight studies were included, of which twenty-six were in vitro. The included studies, published between 2020 and 2025, demonstrated that variations in macro- and micro-geometries influenced both linear and angular trueness. Cylindrical designs with optimal dimensions generally outperformed cuboidal or spherical forms. Structural modifications, such as rigid bar extensions and surface facets, often improved scan accuracy. Some hybrid or modified designs performed comparably to conventional scan bodies. According to QUIN, 27 studies were moderate quality and one had high quality. Conclusions: Scan body geometry affected the accuracy of intraoral implant digital impressions. Designs featuring rigid extensions or simplified geometries improve trueness and precision. Further standardized clinical studies are needed to define optimal design features and validate current in vitro findings. Full article

The present work intends to assess the impact of trochoidal toolpath rounding radius loop adjustments on surface roughness, nose radius wear, and resultant cutting force during end milling of AISI D3 steel. Twenty experimental trials have been performed utilizing a face-centered central composite design through a response surface approach. Artificial Neural Network (ANN) models were built to forecast outcomes, utilizing four distinct learning algorithms: the Batch Back Propagation Algorithm (BBP), Quick Propagation Algorithm (QP), Incremental Back Propagation Algorithm (IBP), and Levenberg–Marquardt Back Propagation Algorithm (LMBP). The efficacy of these models was evaluated using RMSE, revealing that the LMBP model yielded the lowest RMSE for surface roughness (Ra), nose radius wear, and resultant cutting force, hence demonstrating superior predictive capability within the trained dataset. Additionally, a Genetic Algorithm (GA) was employed to ascertain the optimal machining settings, revealing that the ideal parameters include a cutting speed of 85 m/min, a feed rate of 0.07 mm/tooth, and a rounding radius of 7 mm. Moreover, the detachment of the coating layer resulted in alterations to the tooltip cutting edge on the machined surface as the circular loop distance increased. The initial arc radius fluctuated by 33.82% owing to tooltip defects that alter the edge micro-geometry of machining. The measured and expected values of the surface roughness, resultant cutting force, and nose radius wear exhibited discrepancies of 6.49%, 4.26%, and 4.1%, respectively. The morphologies of the machined surfaces exhibited scratches along with laces, and side flow markings. The back surface of the chip structure appears rough and jagged due to the shearing action. Full article

This article presents the implementation of the Six Sigma methodology in the electro-discharge texturing process of cold mill work rolls. The final surface quality of sheet metal must meet the specific demands of car body part producers, which require a specific surface texture described by surface microgeometry parameters: the average roughness and the peak density. The requirements for the surface microgeometry of sheet metal are mainly related to improving the formability and adhesion of the paint in the body painting process. These microgeometry parameters can be controlled by the texture of work rolls: this texture is transferred onto the sheet metal surface. The electro-discharge texturing process allows for control of the average roughness and peak density according to individual customer specifications. In this study, a model is proposed to predict the average roughness based on the input parameters of the electro-discharge texturing process: current, voltage, and time. Compared to previous models, this model includes more input parameters. The process suitability was analyzed using control charts, capability indices, and Z scores. The modified weighted product method was used to create a purpose function describing the relationships between the input and output quality parameters. Based on the agreement of the target quality characteristics and the calculated values according to the models obtained, an algorithm to control the texturing process of the work rolls was designed. The proposed model was also validated on results published by other authors and demonstrated good agreement. This study should contribute to the philosophy of continuously improving the surface quality of cold-rolled sheet metal. Full article

The study evaluates models produced using fused deposition modeling (FDM) technology in five orientations, fabricated from polycarbonate (PC) material with a FORTUS 360mc printer. The models included simple shapes (planes and cylinders) and complex free-form surfaces. Accuracy was assessed using a GOM Scan 1 scanner and GOM Inspect 2019 software, focusing on 3D deviations and dimensional and geometric deviations (form, position, and orientation, which have not yet been analyzed in similar studies and may limit the usage of the printed elements). Surface roughness was analyzed using a MarSurf XR profilometer, measuring Ra and Rz parameters. All models were characterized by a predominance of negative 3D deviations. The analysis of variance showed no effect of model orientation on the values of linear dimensional deviations and geometric deviations. The largest deviations were negative and associated with the size of the models. The average value of the absolute deviation of linear dimensions associated with the size of the model was 0.30 mm. The average value of the absolute deviation of other linear dimensions was 0.07 mm. The average value of orientation and position deviations for each model varied in the range of 0.15–0.20 mm, and for form deviation 0.16–0.20 mm. One of the models had a higher surface roughness (Ra = 17.2 µm, Rz = 71.3 µm) than the other four models (Ra in the range of 12.7–13.8 µm, Rz in the range of 57.2–61.2 µm). During the research, three distinct surface types were identified on the models. The research indicated the validity of taking surface type into account when analyzing its microgeometry. Full article

Microbubbles, acting as cavitation nuclei, undergo cycles of expansion, contraction, and collapse. This collapse generates shockwaves, alters local shear forces, and increases local temperature. Cavitation causes severe changes in pressure and temperature, resulting in surface erosion. Shockwaves strip material from surfaces, forming pits and cracks. Prolonged cavitation reduces the mechanical strength and fatigue life of materials, potentially leading to failure. Controlling bubble size and generating monodispersed bubbles is crucial for accurately modeling cavitation phenomena. In this work, we generate monodispersed microbubbles with controllable size using a novel and low-cost microfluidic method. We created an innovative T-junction structure that controls the two-phase flow for tiny, monodispersed bubble generation. Monodisperse microbubbles with diameters below one-fifth of the channel width (W = 100 µm) are produced due to the controlled pressure gradient. This microstructure, fabricated by a CNC milling technique, produces 20 μm bubbles without requiring high-resolution equipment and cleanroom environments. Bubble size is controlled with gas and liquid pressure ratio and microgeometry. This microbubble generation method provides a controllable and reproducible way for cavitation research. Full article

Surface microgeometry created by the energy of electric discharges is related to surface wetting behavior. These relationships change depending on the scale of observation. In this work, contact angles correlated with the surface complexity of AA 6060 after electro-discharge machining were analyzed at different observation scales. This research focuses on the methodology of selecting the best scales for observing wetting phenomena on irregular surfaces, as well as indicating the topographic characterization parameters of the surface in relation to the scales. Additionally, the geometric features of the surface that determine the contact angle were identified. In this study, the surfaces of an aluminum alloy are rendered using focus variation 3D microscopy and described by standardized ISO, area-scale, and length-scale parameters. The research also confirms that it is possible to design surface wettability, including its hydrophilicity and hydrophobicity, using electrical discharge machining parameters. The static and dynamic behavior of liquids on surfaces relevant to contact mechanics was also determined. Full article

This investigation sought to characterize the combined influence of cutting-edge microgeometry and cooling/lubricating strategies on process thermo-mechanics and the resultant surface integrity in orthogonal machining of the Ti-6Al-4V alloy. Reverse waterfall cutting inserts were prepared with varying cutting-edge geometries, and machining experiments were conducted under cryogenic cooling with liquid nitrogen (LN₂), minimum quantity lubrication (MQL), and dry machining conditions, using constant machining parameters. The induced surface integrity was characterized in terms of the developed cutting forces and through-thickness microhardness, grain morphology, dislocation generation, and residual stress formation. The experimental results revealed that the governing process physics are strongly influenced by variation in the implemented machining parameters. As a greater proportion of the cutting edge is distributed on the flank face, competing mechanical ploughing and thermal-based frictional effects both become more pronounced. Utilization of advanced cooling strategies to control cutting interface thermal gradients thus provides a processing route to generate tailored microstructures and surface integrity during the machining of this alloy. Full article

The selection of the right tool path trajectory and the corresponding machining parameters for end milling is a challenge in mold and die industries. Subsequently, the selection of appropriate tool path parameters can reduce overall machining time, improve the surface finish of the workpiece, extend tool life, reduce overall cost, and improve productivity. This work aims to establish the performance of end milling process parameters and the impact of trochoidal toolpath parameters on the surface finish of AISI D3 steel. It especially focuses on the effect of the tool tip nose radius deviation on the surface quality using precision measurement techniques. The experimental design was carried out in a systematic manner using a face-centered central composite design (FCCD) within the framework of response surface methodology (RSM). Twenty different experiment trials were conducted by changing the independent variables, such as cutting speed, feed rate, and trochoidal pitch distance. The main effects and the interactions of these parameters were determined using analysis of variance (ANOVA). The optimal conditions were identified using a multiple objective optimization method based on desirability function analysis (DFA). The developed empirical models showed statistical significance with the best process parameters, which include a feed rate of 0.05 m/tooth, a trochoidal pitch distance of 1.8 mm, and a cutting speed of 78 m/min. Further, as the trochoidal pitch distance increased, variations in the tool tip cutting edge were observed on the machined surface due to peeling off of the coating layer. The flaws on the tool tip, which alter the edge micro-geometry after machining, resulted in up to 33.83% variation in the initial nose radius. Deviations of 4.25% and 5.31% were noted between actual and predicted values of surface roughness and the nose radius, respectively. Full article

The paper investigates the feasibility of plasma electrolytic treatment (PET) of 90CrSi tool steel to enhance hardness and wear resistance. The influence of electrophysical parameters of PET (polarity of the active electrode, chemical-thermal treatment, and polishing modes) on the composition, structure, morphology, and tribological properties of the surface was studied. Tribological tests were carried out under dry friction conditions according to the shaft-bushing scheme with fixation of the friction coefficient and temperature in the friction contact zone, measurements of surface microgeometry parameters, morphological analysis of friction tracks, and weight wear. The formation of a surface hardened to 1110–1120 HV due to the formation of quenched martensite is shown. Features of nitrogen diffusion during anodic PET and cathodic PET were revealed, and diffusion coefficients were calculated. The wear resistance of the surface of 90CrSi steel increased by 5–9 times after anodic PET followed by polishing, by 16 times after cathodic PET, and up to 32 times after subsequent polishing. It is shown that in all cases, the violation of frictional bonds occurs through the plastic displacement of the material, and the wear mechanism is fatigue wear during dry friction and plastic contact. Full article