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Chip formation is considered one important indicator to evaluate machining processes. In particular, geometric features of chips may provide important insights for the assessment of machining stability and productivity. In fixed-abrasive machining processes, such as grinding and honing, chips are simultaneously produced by many of the geometrically undefined cutting edges. Despite being "undefined," geometric features of abrasive grains can still be statistically characterized or described. Accordingly, it can be assumed that, under stable machining conditions, the geometric features of abrasive chips may also conform to certain statistical patterns. However, statistical characterization of abrasive chips can be very challenging due to their large quantity, irregular shapes, minuscule size, and sometimes tangled condition. In this study, an analysis method combining metallographic preparation and micro-computed tomography (micro-CT) has been developed to characterize abrasive chips produced by a honing stone. The results regarding the geometric characteristics of the obtained massive abrasive chips, i.e., their sizes and shapes, were presented and statistically described. It was found most chips had a size around 50 µm and the shape being a slightly elongated and curved cone. Most of the geometric features could meet a positive skewness distribution. [ABSTRACT FROM AUTHOR]

The existence of striations, and scratches in Abrasive waterjet (AWJ) cutting surface necessitates an exploration of these features for enhancing the cutting accuracy of AWJ machining. This article investigates surface roughness and micro-scratch morphology characteristics on brass cutting surfaces. According to the variation law of surface roughness values, the cutting section can be divided into three regions: the initial region, smooth region, and rough region. Numerous micron-scale scratches were observed in the cutting section. The scratch length, width, and depth values all show an increasing trend as the cutting depth increases, with the scratch length experiencing the greatest growth and variability. The influence of position and traverse speed on scratch size was studied using variance analysis. Furthermore, the length and width of the scratches on the cutting surface are significantly influenced by their position, accounting for 89.19% and 81.13%, respectively. Traverse speed had a minor effect on scratch length and width, accounting for 0.01% and 2.64% respectively. The depth of the scratches is influenced by their position on the cutting surface at a rate of 41.12%, while traverse speed had an impact of 38.10%. Finally, a mathematical method based on standard scores was proposed to assess the quality of the cutting section based on micro-scratch dimension. [ABSTRACT FROM AUTHOR]

Abrasive machining processes have long been integral to various manufacturing industries, enabling precise material removal and surface finishing. In recent years, the integration of non-Newtonian fluids has emerged as a promising strategy to enhance the performance and efficiency of these processes. This review paper provides a comprehensive overview of the current state of research on abrasive machining processes, including abrasive lapping, abrasive polishing, and chemical mechanical polishing, and then analyzes in detail the abrasive machining processes enhanced with non-Newtonian fluids. It explores the fundamental principles underlying the rheological behavior of non-Newtonian fluids and their application in abrasive machining, with a focus on shear-thickening fluids. The paper will begin by introducing the abrasive machining processes, including abrasive lapping, abrasive polishing, and chemical mechanical polishing. Then, the current research status of non-Newtonian fluids will be comprehensively analyzed, and we will explore the enhancement of abrasive machining processes with non-Newtonian fluids. Finally, the paper will conclude with a discussion of the future directions and challenges in the field of abrasive machining enhanced with non-Newtonian fluids. Overall, this review aims to provide valuable insights into the potential benefits, limitations, and opportunities associated with the use of non-Newtonian fluids in abrasive machining, paving the way for further research and innovation in this promising area of manufacturing technology. [ABSTRACT FROM AUTHOR]

This paper introduces an Acoustic Emission (AE)-based monitoring method designed for supervising the Abrasive Waterjet Cutting (AWJC) process, with a specific focus on the precision cutting of Carbon Fiber-Reinforced Polymer (CFRP). In industries dealing with complex CFRP components, like the aerospace, automotive, or medical sectors, preventing cutting system malfunctions is very important. This proposed monitoring method addresses issues such as reductions or interruptions in the abrasive flow rate, the clogging of the cutting head with abrasive particles, the wear of cutting system components, and drops in the water pressure. Mathematical regression models were developed to predict the root mean square of the AE signal. The signal characteristics are determined, considering key cutting parameters like the water pressure, abrasive mass flow rate, feed rate, and material thickness. Monitoring is conducted at both the cutting head and on the CFRP workpiece. The efficacy of the proposed monitoring method was validated through experimental tests, confirming its utility in maintaining precision and operational integrity in AWJC processes applied to CFRP materials. Integrating the proposed monitoring technique within the framework of digitalization and Industry 4.0/5.0 establishes the basis for advanced technologies such as Sensor Integration, Data Analytics and AI, Digital Twin Technology, Cloud and Edge Computing, MES and ERP Integration, and Human-Machine Interface. This integration enhances operational efficiency, quality control, and predictive maintenance in the AWJC process. [ABSTRACT FROM AUTHOR]

This study introduces innovative designs for abrasive tools aimed at enhancing surface finishing processes. Prototypes consisting of non-continuous abrasive films with discontinuous surface carriers and abrasive layers were developed to improve the efficiency and effectiveness of the smoothing process. Four distinct abrasive films with varying nominal grain sizes were fabricated to explore the versatility and efficacy of the prototypes. The results indicate that the incorporation of carrier irregularities significantly influences surface finishing processes, leading to improvements in material removal efficiency and surface quality. Longitudinal discontinuities facilitate faster removal of irregularities from workpiece materials, reducing the risk of deep scratches on surfaces. Additionally, this study highlights the importance of tool motion patterns in optimizing material removal processes and ensuring surface quality. The integration of carrier irregularities with additional oscillatory tool motion shows promise for further improving surface quality. These findings advance our understanding of abrasive machining processes and provide valuable insights for optimizing abrasive tool designs and machining strategies for enhanced surface finishing. [ABSTRACT FROM AUTHOR]

To investigate the rail repair process based on high-pressure abrasive water jet, simulation analysis of its machining process is carried out based on smoothed particle hydrodynamics with finite element method (SPH-FEM). First, through the water jet cutting experiment, analysis of simulation data and experimental results are compared, and the results are basically the same in terms of values and trends. The depth of cut decreases with the increase of transverse speed, increases with the increase of abrasive flow, and tends to increase and then decrease with the jet pressure and target distance. Then, the rail top surface is repaired by high-pressure abrasive water jet technology, and the experimental results show that the repaired rail surface fully meets the rail grinding and repair standards. The repaired rail surface roughness of 2.648 μm is better than the rail milling train repair index value of 56.2%, which verifies the feasibility and effectiveness of rail repair based on high-pressure abrasive water jet technology. [ABSTRACT FROM AUTHOR]

Non-conventional machining processes offer significant advantages over conventional ones, especially in terms of the productivity, cost, and surface integrity of the produced parts due to their higher flexibility. Abrasive waterjet machining, in particular, constitutes an ecologically friendly process with a negligible thermal impact on a workpiece, and it has considerable capabilities for obtaining the desired outcome by regulating some of its numerous parameters. Among these parameters, the abrasive type is particularly important due to its hardness, mesh size, and shape, which lead to considerable deviations on the obtained depth, kerf characteristics, and productivity. Thus, in this work, a comprehensive comparison is conducted on the use of garnet and silicon carbide particles for the slot milling of the Ti-6Al-4V alloy under different conditions. The capabilities of both abrasive materials are evaluated by statistical analysis regarding the depth of penetration, kerf width, kerf taper angle, and material removal rate (MRR), which are obtained under the same process conditions. Finally, a multi-objective optimization based on grey relational analysis (GRA) is performed for several different practical cases. It was found that, although silicon carbide is more efficient in optimizing individual process outputs, the use of a garnet abrasive can lead to considerably better trade-offs between two or more objectives of the machining process. [ABSTRACT FROM AUTHOR]

The presented paper is focused on the evaluation of material removal during machining via an abrasive water jet with a controlled depth of cut. In the introductory parts of the work, a theoretical analysis of water jet technology and an analysis of the current state of the problem are presented. The experimental part of the work is devoted to testing the effects of technological parameters on material removal from the point of view of the maximum erosion depth and volume loss of material during machining with a low water pressure of 50 MPa. The tested material was a Ti 6Al 4V titanium alloy. The experiments were carried out by changing the traverse speed of the cutting head, the mass flow of the abrasive and the angle of inclination of the cutting head, according to the DoE 33 experiment plan. The obtained values were evaluated using the method of variance (ANOVA) and regression analysis. Furthermore, the values of the width of the erosion track and the maximum and minimum erosion effects for both tested materials were evaluated. [ABSTRACT FROM AUTHOR]

As time passes, a significant number of reinforced concrete (RC) constructions will require maintenance and transformation. RC repair and renovation often require localized crushing and removal of the distressed area. Abrasive water jet (AWJ) crushing RC has significant advantages in terms of safety, environmental protection, and quality. However, AWJ works with high specific energy consumption and the effective crushing range of the jets is small, and the key to solving these problems lies in an in‐depth study of the general destructive law and cracking mechanism of RC materials under the action of high‐speed liquid impact. Therefore, this thesis focuses on the above key scientific issues, combining mechanical impact tests, smooth particle hydrodynamics numerical simulation methods and computer tomography scans techniques to carry out systematic research. Through the study, it is found that: The fracture characteristics of RC are mainly reflected in crushing pits and cracks, which will produce macrocracks extending along the reinforcement on the side of RC. AWJ impacting RC is mainly divided into three stages: crater formation, upper concrete fragmentation, and concrete damage development in the reinforcement impact area. During the whole impact process, the shear stress, compressive stress and tensile stress of the reinforcement will change continuously with the increase of the impact time of the AWJ. [ABSTRACT FROM AUTHOR]

This paper presents the research results on the influence of vibration abrasive machining parameters on the surface layer integrity of elements made by LPBF technology from Inconel 939. The research was carried out on samples of various sizes on vibrating smoothing machines. The influence of the size of the processed elements, the type of abrasive shapes, the processing time, and the supporting fluid on the surface roughness and microstructure of the processed elements was analyzed. Tests have shown that as a result of using vibration processing, it is possible to reduce the surface roughness five times to the value of Ra = 1.1 µm. A significant influence of the type of abrasive shapes was found. There was no significant effect of the machining fluid on the process. [ABSTRACT FROM AUTHOR]

Radial jet drilling (RJD) is an innovative geological resource development technology. Swirling impeller abrasive water jet (SAWJ) is an excellent rock drilling method and is expected to drill larger branches during RJD. However, the rock drilling performance of a SAWJ is affected by various parameters. Here, we conducted SAWJ rock drilling experiments under different parameter combinations. Jet-drilled hole morphology, diameter, depth and volume were utilized to evaluate the rock drilling performance. Besides the SAWJ rock-breaking mechanisms, differences between SAWJ and conical abrasive water jet were discussed. The results indicated that the SAWJ has the ability to create a large diameter (56 ~ 79 mm) hole on granite, limestone, conglomerate, gray sandstone, yellow sandstone and coal. The jet-drilled hole diameter strongly depends on standoff distance, and large hole diameter was obtained at a long standoff distance. The jet-drilled hole depth and volume tends to increase with an increase in the jetting pressure, abrasive mass concentration, abrasive particle diameter and exposure time and with a decrease in the standoff distance. The critical jetting pressure and effective standoff distance were 10 MPa and 30 mm, respectively. Besides, the rock failure modes during SAWJ drilling are not only the compressive failure but also the tensile failure and shear failure. In addition, the SAWJ has the characteristics of large impact area (28.26 cm2) and short effective standoff distance (3 cm). The experiments results are expected to provide a theoretical basis for parameters selection during RJD filed applications. Highlights: SAWJ rock drilling performance under different parameter combinations were studied by laboratory experiments. SAWJ had the ability to break the common rocks during RJD process and created a large diameter hole (56-79 mm). The critical jetting pressure and effective standoff distance of SAWJ in our experiments were 10 MPa and 30 mm, respectively. [ABSTRACT FROM AUTHOR]

In recent years, biocomposites are developed to tackle the environmental legislation towards sustainable growth with renewable resources. Biocomposites are the most promising materials owing to their high strength-to-weight ratio and competitive cost. Among several biocomposites, Jute fiber and wood plastic composites (WPC) are preferred due to their wide applicability and availability. Abrasive water jet machining (AWJM) is a proven process for machining such biocomposites as it overcomes the drawbacks of conventional machining processes such as delamination and heat generation. In this work, experimental investigations for the effect of AWJM process parameters such as Standoff Distance, Traverse Speed and Water Pressure on responses Surface Roughness (Ra) and Kerf Taper Angle (Ta) for Jute Fiber and WPC through nanoabrasives-assisted AWJM have been carried out. The experiments are designed using response surface methodology (RSM) and further optimized using a genetic algorithm (GA). It is observed that water pressure is the most significant parameter irrespective of the material since higher pressure always yields better results compared to the lower pressure owing to the kinetic energy (impact) and molecular dynamics of abrasives. Further, this work explores the applicability of nanosized aluminum oxide as abrasives and results show that nanoparticles have significantly improved the surface finish. [ABSTRACT FROM AUTHOR]

Purpose: Three-dimensional (3D) printed parts usually have poor surface quality due to layer manufacturing's "stair casing/stair-stepping". So post-processing is typically needed to enhance its capabilities to be used in closed tolerance applications. This study aims to examine abrasive flow finishing for 3D printed polylactic acid (PLA) parts. Design/methodology/approach: A new eco-friendly abrasive flow machining media (EFAFM) was developed, using paper pulp as a base material, waste vegetable oil as a liquid synthesizer and natural additives such as glycine to finish 3D printed parts. Characterization of the media was conducted through thermogravimetric analysis and Fourier transform infrared spectroscopy. PLA crescent prism parts were produced via fused deposition modelling (FDM) and finished using AFM, with experiments designed using central composite design (CCD). The impact of process parameters, including media viscosity, extrusion pressure, layer thickness and finishing time, on percentage improvement in surface roughness (%ΔRa) and material removal rate were analysed. Artificial neural network (ANN) and improved grey wolf optimizer (IGWO) were used for data modelling and optimization, respectively. Findings: The abrasive media developed was effective for finishing FDM printed parts using AFM, with SEM images and 3D surface profile showing a significant improvement in surface topography. Optimal solutions were obtained using the ANN-IGWO approach. EFAFM was found to be a promising method for improving finishing quality on FDM 3D printed parts. Research limitations/implications: The present study is focused on finishing FDM printed crescent prism parts using AFM. Future research may be done on more complex shapes and could explore the impact of different materials, such as thermoplastics and composites for different applications. Also, implication of other techniques, such as chemical vapour smoothing, mechanical polishing may be explored. Practical implications: In the biomedical field, the use of 3D printing has revolutionized the way in which medical devices, implants and prosthetics are designed and manufactured. The biodegradable and biocompatible properties of PLA make it an ideal material for use in biomedical applications, such as the fabrication of surgical guides, dental models and tissue engineering scaffolds. The ability to finish PLA 3D printed parts using AFM can improve their biocompatibility, making them more suitable for use in the human body. The improved surface quality of 3D printed parts can also facilitate their sterilization, which is critical in the biomedical field. Social implications: The use of eco-friendly abrasive flow finishing for 3D printed parts can have a positive impact on the environment by reducing waste and promoting sustainable manufacturing practices. Additionally, it can improve the quality and functionality of 3D printed products, leading to better performance and longer lifespans. This can have broader economic and societal benefits. Originality/value: This AFM media constituents are paper pulp, waste vegetable oil, silicon carbide as abrasive and the mixture of "Aloe Barbadensis Mill" – "Cyamopsis Tetragonoloba" powder and glycine. This media was then used to finish 3D printed PLA crescent prism parts. The study also used an IGWO to optimize experimental data that had been modelled using an ANN. [ABSTRACT FROM AUTHOR]

Abrasive water jet polishing has significant advantages in the manufacturing of complex optical components (such as high-slope optical component cavities) that require high-precision manufacturing. This is due to its processing process, in which the polishing tool does not make direct contact with the surface of the workpiece, and instead maintains a considerable distance. However, the removal functions of most existing abrasive water-jet polishing technologies do not possess strict symmetry, which significantly impacts the ability to correct surface figure errors. Therefore, this study implements rotating abrasive water-jet polishing based on traditional abrasive water jet processing to optimize the removal function, which turns it into a Gaussian form; thus, obtaining a type of removal function more suitable for CCOS polishing. This paper derives an empirical formula between the distance s' from the peak removal point of the removal function to the stagnation point and the nozzle tilt angle α, based on geometric relationships and experimental results, analyzes the relationship between material removal efficiency, nozzle tilt angle, and standoff distance. Finally, this paper verifies through experiments the validity of this empirical formula under different process parameters. Therefore, this study obtains the process conditions that allow rotating abrasive water-jet polishing technology to achieve a stable Gaussian form removal function, and the appropriate process parameters to be selected in conjunction with polishing efficiency; thereby, effectively improving the removal function's corrective ability and manufacturing efficiency. It provides theoretical support for the processing capability and process parameter selection of abrasive water-jet polishing technology, solves the problem of limited shaping capability of existing abrasive water jet tools, and significantly improves the manufacturing capability of high-end optical components. [ABSTRACT FROM AUTHOR]

Permanently increasing requirements for the accuracy of abrasive jet machining (AJM) predetermine a need to increase requirements for the rational choice of the related energy-efficient technological equipment. Due to the relatively cheap and high-quality cleaning of materials from contaminants using AJM, the problem of increasing the energy efficiency of the corresponding equipment based on the rational choice of nozzle geometry becomes more topical. This is also because the working nozzle is a consumable part that requires periodic replacements. Therefore, this article deals with rational designing working nozzles as a reliable way to decrease the power consumption of the compressor equipment while engaging in AJM. For this purpose, experimental and numerical studies of the operating processes in the nozzle were carried out. The main idea of increasing the nozzle's efficiency was to reduce the contact area between the working flow and the nozzle. Due to this, the friction of the abrasive material with its walls was decreased. As a result, the AJM was accelerated, and the energy consumption of the corresponding compressor equipment was reduced. The research showed that a decrease in the nozzle's length up to 4 mm increased the flow ratio by 84% and decreased the energy consumption of the 40 kW compressor unit by 4.5 times. [ABSTRACT FROM AUTHOR]

The paper shows performance optimization effects of steel machining by abrasive water jet (AWJ). An innovative combinative distance-based assessment method (CODAS) is implemented for the optimization of cutting parameters like pump pressure, feed rate, and abrasive flow rate over cutting depth, and cut kerf surface roughness. The CODAS algorithm is among those based on measuring the distance between a scenario (in this case processing parameters in terms of performance and quality indicators) - and a certain benchmark. A benchmark is a specific hypothetical set of processing parameters devised or determined from available data. To determine the best set of process control parameters, a CODAS approach was performed with some weighting determinations. To set the initial parameters of the weights, it was proposed to calculate based on entropy weight method (EWM), that measures output value dispersion in cutting process. This technique simplifies multiple compound responses by preserving a single response. [ABSTRACT FROM AUTHOR]

To improve medical device hole inner wall quality and overcome issues of traditional abrasive flow methods—limited fluidity in small holes causing deformation due to high inner wall pressure, and slow processing with low viscosity abrasives—a new method called shear thickening abrasive flow polishing is suggested. It uses shear thickening fluid as the medium. By leveraging the Preston equation and fluid dynamics theory, this study establishes both an abrasive flow dynamics model and a material removal model for the shear thickening abrasive flow machining of small titanium alloy hole workpieces in medical instruments. Utilizing the COMSOL software, the flow field state of shear thickening fluid within small holes is examined under varying flow behavior indexes and flow velocities. The findings demonstrate that shear thickening fluid yields superior polishing effects compared to Newtonian fluid. Elevating the flow behavior indexes facilitates a higher material removal rate on the inner wall surface; however, excessively large flow behavior indexes diminish the uniformity of material removal, thereby hindering the attainment of a high-quality polished surface. Furthermore, excessively large flow behavior indexes can reduce fluidity and consequently lower the efficiency of the polishing process. Conversely, while maintaining a constant flow behavior index, increasing the flow velocity contributes to an enhanced material removal rate and improved polishing efficiency. Nevertheless, as the flow velocity rises, the uniformity of inner wall surface roughness diminishes, posing challenges in achieving a high-quality polished surface. [ABSTRACT FROM AUTHOR]

Abrasive water jet machining technology is an unconventional special process technology; its jet stream has high energy, and its machining process is characterized by no thermal deformation, no pollution, high applicability, and high flexibility. It has been widely used for processing different types of materials in different fields. This review elaborates on the basic principles and characteristics of abrasive water jet processing, the mechanism of erosion, the simulation of the processing, the influence of process parameters in machining removal, and the optimization of improvements, as well as introduces the current application status, new technology, and future development direction of abrasive water jet technology. This review can provide an important information reference for researchers studying the machining processing of abrasive water jet technology. [ABSTRACT FROM AUTHOR]

Fiber-reinforced additive manufacturing components have been used in various industrial applications in recent years, including in the production of aerospace, automobile, and biomedical components. Compared to conventional methods, additive manufacturing (AM) methods can be used to obtainin lighter parts with superior mechanical properties with lower setup costs and the ability to design more complex parts. Additionally, the fabrication of onyx composites using the conventional method can result in delamination, which is a significant issue during composite machining. To address these shortcomings, the fabrication of onyx composites via additive manufacturing with the Mark forged 3D-composite printer was considered. Machinability tests were conducted using abrasive water jet machining (AWJM) with various drilling diameters, traverse speeds, and abrasive mass flow rates. These parameters were optimized using Taguchi analysis and then validated using the Genetic algorithm (GA) and the Moth Flame Optimization algorithm (MFO). The surface morphology (Dmax) and the roughness of the drilled holes were determined using a vision measuring machine with 2D software (MITUTOYO v5.0) and a contact-type surface roughness tester. Confirmation testing demonstrated that the predicted values werenearly identical to the experimental standards. During the drilling of an onyx polymer composite, regression models, genetic algorithms and the Moth-Flame Optimization algorithm were used to estimate the response surface of delamination damage and surface roughness. [ABSTRACT FROM AUTHOR]

Cryogenic micro-abrasive air-jet machining (CAJM) is a promising future processing technology based on traditional blasting technology. Channel profile is one of the most important indexes to evaluate the performance of PDMS micro-channel. The single-factor experiment of CAJM of PDMS micro-channel was conducted to explore the influence of machining speed, machining pressure, machining angle, and machining distance on channel profile. The BP neural network prediction model of depth-to-width aspect ratio of micro-channel width and depth was established to carry out virtual orthogonal experiment that was applied to explore the limits of the processing capability. The results show that when machining angle is 75° and 90°, the liquid nitrogen jet will promote the discharge of abrasives and chips, and inhibit the secondary machining of the rebound abrasive. The prediction errors of depth-to-width aspect ratio is -4.6%. The maximum depth-to-width aspect ratio obtained by the self-built experimental device was r = 1.938. [ABSTRACT FROM AUTHOR]

The wall-slip velocity of abrasive medium is a key factor concerning workpiece material removal rate (MRR) in abrasive flow machining (AFM) process. However, the coupling effect of wall shear stress and workpiece surface roughness on wall-slip characteristics is little addressed. In this work, a novel method based on fluid mechanics and AFM experiments was proposed to determine wall-slip velocity. The coupling effect of wall shear stress and workpiece surface roughness on wall-slip velocity was then explored. Power-law mathematical models of wall-slip velocity were derived then by nonlinear fitting method, and verification test was finally carried out to validate above models. Results showed that wall-slip velocity increases with increasing wall shear stress and decreasing workpiece surface roughness. Prediction errors using the proposed power-law model, free-slip model, and no wall-slip model were 6.7%, 20.1%, and 98.1%, respectively, so above method, mathematical model, and analysis were verified. This work provides a theoretical basis to improve the prediction accuracy of MRR in AFM process. [ABSTRACT FROM AUTHOR]

This paper aims to optimize the accuracy of the Abrasive Water Jet (AWJ) cutting process. The AWJ technology is a fast-growing production technology that competes with conventional machining methods due to its ability to cut various materials and conduct precise cutting of complex contours. In this research, the AWJ cutting process was tested on 18CrNiMo7-6 steel using almandine garnet type J80A as the abrasive material. The Taguchi method was used to optimize the process parameters. As control parameters chosen abrasive flow rate, pressure, and traverse speed. The output parameters measured were surface roughness and taper angle. The results shown managed to find the optimal combinations of control process parameters causing the lowest surface roughness and taper angle. The study provides insights into how the Taguchi method can be used to optimize the AWJ cutting process to achieve greater accuracy. [ABSTRACT FROM AUTHOR]

Hard brittle materials such as ceramics and crystals are commonly utilized in various industries, including information technology, mechanical engineering, and semiconductors. These materials, known for their high brittleness and hardness but low fracture toughness, pose challenges in efficient and high-quality machining. Current abrasive machining techniques involve rough grinding, fine grinding, and polishing processes, with the latter being the most time-consuming and accounting for over half of the total machining time. Improving processing parameters in rough and fine grinding can increase machining efficiency, reduce surface and subsurface damage, and improve workpiece quality, ultimately reducing the polishing time. This paper explores the abrasive scratching of hard brittle materials, examining the nucleation and propagation of cracks causing surface and subsurface damage, and the underlying mechanisms. The research provides suggestions for enhancing abrasive machining efficiency and ensuring the surface quality of hard brittle materials. [ABSTRACT FROM AUTHOR]

Automate finishing processes is a global challenge in several industrial sectors. Concretely, when dealing with aero-engine components, only simple finishing processes are automated nowadays. Most of the high-added value components manufactured are finished hand working, using deburring and polishing manual techniques. The driver of the proposed work is to achieve the necessary knowledge to introduce in a production line a complete finishing process for automated robotic deburring applications with low machinability materials (Inconel 718 in this case-study) on aero-engine casings with complex geometries: extruded casting bosses, internal features, etc. For this purpose, a three-step methodology is presented and analysed, providing a feasible workflow combining visual inspection for part positioning and edge location, with multi-edge solid tools and flexible abrasive tools to automate finishing operations, taking into account all process singularities. Results show that, using correct techniques, processes and parameters, an automated finishing process reducing operating time can be implemented in production lines. [ABSTRACT FROM AUTHOR]

The article presents the processes and considerations for thinning a large, warped die to a uniform thickness of 50 +/- 2 microns, and suggests that the entire die can be thinned to 50 microns for initial evaluation of silicon thickness. It further provides guidance on the limits of thinning processes, the selection of the size of the area of interest, and the importance of limiting the area thinned to a small fraction of the die surface.

To improve the ultrasonic energy and realize far-field ultrasonic abrasive machining of complex surfaces, a spherical-array-focused ultrasonic abrasive machining system was established. By combining ultrasonic field simulation, detection and a single-factor experiment, the influences of the ultrasonic generator current, abrasive concentration, and particle size on the material removal properties and surface quality evolution of quartz glass were investigated. When the current was less than 0.4 A, the material removal showed plastic removal at the nanoscale. When the current was more than 0.5 A, the cavitation phenomenon formed micron-scale impact removal traces on the workpiece surface. The increase in abrasive concentration increased the impact density and material removal rate, while excessive abrasive concentration increased the impeding effect between abrasive particles and reduced the material removal rate. Moreover, the increase in abrasive particle concentration enhanced heterogeneous cavitation nucleation, promoted the removal of abrasive impact materials under the action of a cavitation jet, and inhibited the removal of direct surface cavitation. The abrasive particle size affects the heterogeneous cavitation nucleation and the acceleration of the cavitation jet on abrasive particles, which affects the material removal rate and surface quality. By controlling the energy of the focused ultrasound and abrasive parameters, the plastic or brittle domain removal of quartz glass can be achieved at the micro- and nanoscales. [ABSTRACT FROM AUTHOR]

High-speed abrasive water jet machining (AWJM) is a universal tool for manufacturing engineering materials. However, the application of AWJM is greatly limited due to the jet lag value caused by the cutting front profile. This paper proposes a new method to predict jet lag values at different cutting depths. The novelty is that a simplified mathematical model of the cutting front profile is developed based on the energy balance theory. Two groups of experiments were conducted to investigate the influences of process parameters on the jet lag value and the dissipated energy during cutting. The numerical regression method is adopted to obtain the energy dissipation function, which has taken the key parameters such as material property, cutting depth, traverse speed, and the initial water jet energy into consideration. The predicted curves are compared with experimental results under different operating situations with the least value of R 2 = 0.9136 and the maximum deviation in percent of 16% at the jet exit point. The proposed method contributes to further research on product distortion in abrasive water jet cutting. • A new mathematical model is established to predict the jet lag values at different depths based on the energy balance approach. • The analysis of variance regression method is adopted to obtain the energy dissipation function. • The influences of key parameters on the dissipated energy are systematically analyzed. [ABSTRACT FROM AUTHOR]

Abrasive machining has been used for inner surface processing of various hollow components. In this study, we applied an in-air fluid jet as a precision machining method for the inner surface of an axisymmetric x-ray mirror whose inner diameter was less than 10 mm. We employed an abrasive with a polyurethane@silica core–shell structure, which has a low density of about 1.2 g/cm3 and a relatively large particle size of about 15 µm. By using this abrasive, a practical removal rate and a smooth machined surface were simultaneously obtained. We performed figure corrections for an axisymmetric mirror and improved the circumferential figure accuracy to a sub-10 nm root mean square level. To evaluate the machining performance in the longitudinal direction of the ellipsoidal surface, we also performed periodic figure fabrication on the inner surface of a 114 mm-long nickel ellipsoidal mirror. X-ray ptychography, an optical phase retrieval method, was also employed as a three-dimensional figure measurement technique of the mirror. The wavefield of the x-ray beam focused by the processed ellipsoidal mirror was observed with the ptychographic system at SPring-8, a synchrotron radiation facility. The retrieval calculations for the wavefront error confirmed that a sinusoidal waveform with a period of 12 mm was fabricated on the mirror surface. These experimental results suggest that a nanoscale figure fabrication cycle for the inner surface consisting of jet machining and wavefront measurement has been successfully constructed. We expect this technique to be utilized in the fabrication of error-free optical mirrors and various parts having hollow shapes. [ABSTRACT FROM AUTHOR]

Mining/marine bushings, biomedical implants, and many more are among the several applications of lightweight elastomer components. The use of non-traditional machining to manufacture these good-quality components in small or batch-size units is required because the primary manufacturing method requires customised mould and follow-up machining. In this regard, the present work focuses on investigating the performance of machining a nitrile rubber (NR) using suspension-type abrasive water jet (AWJ) under both conventional (room temperature) and cryogenic (liquid nitrogen (LN2)) conditions at optimal values of process parameters: water jet pressure (WJP, bar), transverse rate (Vf, mm/min), and stand-off distance (SOD, mm). The experimental runs are designed using Taguchi analysis with respective performance parameters: Kerf taper ratio (KTR) and Material removal rate (MRR, mm³/min). The results show that Vf (Rank 1) is the highest influencing factor on the machining performance of NR under both conditions. The reasons are improved kinetic energy, less collision of garnet abrasive particles and lesser change in the average width of the kerf. The influence of LN2 showed that the optimal values of KTR reduced by 11.97% at 200 bar, 40 mm/min, and 1 mm, and MRR increased by 0.65% at 250 bar, 60 mm/min, and 2.0 mm, respectively. [ABSTRACT FROM AUTHOR]

For complex curved difficult-to-machine parts, a new method based on pneumatic suspension abrasive pool bright finishing processing is proposed, using the mixing of pneumatic suspension abrasive, the workpiece surface, and fluidized abrasive to produce relative motion velocity, so that the solid particles and workpiece surface microscopic two-body abrasive wear to achieve the effect of precision machining. The experimental test material is the widely used Q235 steel plate. The experimental parameters include workpiece shape (round tube, square tube, cylindrical), abrasive particle size (24, 80, 120 mesh count), gas–solid two-phase flow pattern (dispersion fluidization state, turbulent fluidization state, spurting fluidization state), abrasive particle shape (sphere, irregular), and spindle speed (600, 900, 1200 rpm). An orthogonal test was designed according to the experimental parameters, and the degree of influence of each parameter on the processing of the abrasive cell was evaluated by the roughness of the workpiece surface together with the scanning electron microscope (SEM) micrograph of the workpiece surface, and the optimal combination of parameters was judged using the extreme difference method as well as the factor trend diagram. The results show that under the present experimental conditions, the workpiece surface roughness (Ra) can reach a minimum value of 0.4 μm. The feasibility of gas–solid two-phase flow processing is demonstrated from an experimental point of view, and the advantages of abrasive cell processing are explored. [ABSTRACT FROM AUTHOR]

Point grinding is an abrasive machining process that utilizes small diameter superabrasive single-layer grinding tools for accurate machining of complex 3D geometries. Due to the small nature of these tools, high wear-rates and uneven wear around the tool circumference present a challenge for their successful application for the finish machining of metallic components. It is, therefore, essential to monitor the surface condition of the point grinding tools, to ensure their safe and reliable operation. In this investigation, the 3D topography evolution of single-layer B126 cubic boron nitride (cBN) point grinding tools was characterized using focus-variation imaging. Given the wealth of information obtained using this method, a decision-matrix methodology was used to identify the most important parameters for monitoring the wear condition of the point grinding tools. Grinding trials were also performed with fixed cutting parameters and varied cutting durations up to 520 mm3 of material removed to assess the evolution of the point grinding tool surfaces over time as a result of wear during grinding of hardened D2 tool steel. The best criteria for the characterization of the surface texture of electroplated cBN point grinding tool surfaces were identified to be the average surface height (Sa), skewness (Ssk), root mean square gradient (Sdq), reduced peak height (Spk), peak material volume (Vmp), and developed interfacial area ratio (Sdr). These parameters performed best for direct measurement of point grinding tool surfaces, paving the way for the application of the imaging technique under manufacturing conditions as an on-machine monitoring method for performance assessment. [ABSTRACT FROM AUTHOR]

Ultrasonic-assisted magnetic abrasive flow machining (UAMAFM) process shows enhanced finishing performance compared to conventional abrasive flow machining (AFM). In this present research paper, mathematical models for MR and Ra have been developed for the UAMAFM process by considering both steady-state and transient phenomena. The external ultrasonic and magnetic field assistance enhanced the velocity and length of contact of active abrasives, calculated from the kinematic analysis. The resultant finishing forces have also been evaluated by considering these external aids. The steady-state material removal per finishing cycle remains constant and depends on the velocity of motion, length of contact, resulting forces, number of active abrasives, and work material hardness. The transient material removal per finishing cycle was calculated in terms of the volume of irregularities present over the work surface, i.e., initial surface roughness. The mathematical model for surface roughness was developed in terms amount of material removed (MR), and initial (Ra0) and critical surface roughness (Racr)?. The predicted values of material removed and surface roughness from developed mathematical models agreed with experimental results with a deviation of 7.80% and 2.44%, respectively. [ABSTRACT FROM AUTHOR]

The most critical phase of all the stages needed for quality sample preparation for microscopic study is perhaps surface polishing. Magnetic abrasive polishing is a nonconventional finishing operation that can finish different materials and produce nano-finished surfaces. This study emphasizes the fabrication of a magnetic abrasive polishing setup for metallurgical polishing of specimens. Utilizing this test arrangement, exploratory investigations have been conducted to analyze the impact of five significant interaction factors, specifically the gap between the magnetic pole and the workpiece (G), the quantity of diamond-based sintered magnetic abrasives (Q), the rotational speed of the magnetic pole (RPM), the grit size of sintered magnetic abrasives (S), and machining time (T). The abrasives used in this study were diamond-based sintered magnetic abrasives. The percentage change in surface roughness (PCSR) of the stainless steel SS304 workpiece is the response variable. From the results of the ANOVA study, the most important factor affecting the PCSR of the stainless steel SS304 workpiece is the abrasive grit size (49.49%), and the least important factor is the machining time (4.89%). The differences in scanning electron microscopy (SEM) images and surface profiles of workpieces demonstrate that the developed setup can polish stainless steel SS304 plane workpieces. [ABSTRACT FROM AUTHOR]

In the past few decades, sophisticated machining industries have rapidly improved in order to achieve the required shape of a part within a specific time while also not affecting material properties. Accuracy of machined components in all industries is important. In the case of subassemblies of components, geometrical accuracy of hole is vital. The researchers updated their machinery from time to time from this perspective. In the machining process, environment and time are the vital parameters that are mainly affected, so in this case, the design of experiments that are very useful in the machining region needs to be considered to overcome these challenges. This study aims to analyze the fabrication of hot abrasive jet machining (HAJMing) with different abrasive temperatures using fluidized bed system as well as accomplishment of cutting performance in hot-abrasive jet machining concerning target surface erosion. Additionally, this research study accomplishes the experimental study and computational fluid dynamics (CFD) technique for erosive footprint prediction extent in HAJMing constraints on target surface for intricately shaped tapered holes generation. The use of hot abrasives in the HAJM process has demonstrated an interest in improving cutting performance for material erosion. Moreover, this proposed experimental work contains the manufacturing, design and fabrication of hot abrasive jet machine (HAJM) using commercially available hardware and software. So, the components are manufactured indigenously as per the designed parameters for the purpose of improving the machining performance. Simulation for material erosion mechanism of HAJMing is used to obtain the nature of produced workpiece profile. Additionally, FB-HAJMing also deals with the sustainability assessment under environmental-friendly hot abrasive-assisted machining conditions. [ABSTRACT FROM AUTHOR]

This novel implementation will analyse the cutting performance of hardstone aluminium nitride with regards to roughness of the surface and material erosion in hot abrasive jet machining (HAJM). Forty five sets of tests have been carried out taking into account five machining constraints (compressed air pressure, compressed air velocity, abrasive temperature, abrasive grain size and percentage concentration of hot abrasives). To optimise the model and determine the conditions for maximising the erosion rate and minimising the surface roughness, a particle swarm optimisation (PSO) was used with experimental investigation as well as predictive modelling. The results were validated experimentally, and the results were well-established between test results and PSO forecasts. The nature of the produced target profile was obtained through CFD simulation in HAJMing. In addition, HAJMed surface microstructures were analysed with microscopic images. The results of RSM data have been validated by testing and RSM prediction. In addition, a multi-objective optimisation problem based on the empirical models was used and the multi-objective particle swarm optimisation (PSO) were determined. In AlN ceramic materials, the RSM with PSO determined the optimal machining restriction for an exact HAJMing condition. [ABSTRACT FROM AUTHOR]

The demand for high-precision and high-efficient machining of high-performance materials and components has increased in various industries such as optical, automotive, communication, life sciences, and medical sciences. Certain difficult-to-machine materials can be reliably machined using deterministic precision cutting processes. However, hard and brittle materials such as ceramics, carbides, hardened steel molds, glassy materials, or semiconductor materials, require precision abrasive technologies with super abrasives like diamond, cBN, or new tool materials for machining. However, machining high-precision components and their molds/dies using abrasive processes is considerably more difficult due to their complex and non-deterministic nature and textured surfaces. Furthermore, high-energy processes such as laser technology can assist abrasive technologies in ensuring higher precision and efficiency. Precision grinding and polishing processes are primarily used to generate high-quality and functional components, typically made of difficult-to-machine materials. Thus, the surface quality achievable by precision grinding and polishing processes becomes more important for reducing machining time and costs. This special issue features 10 papers on the most recent advances in precision abrasive technologies. These papers cover the following topics: - Ultrasonic grinding of micro holes using cemented WC tools - Drilling holes in CFRP aircraft using cBN electroplated ball end mill - In situ evaluation of drill wear using tool images - Grinding belt based on modified information entropy - Radial directional vibration-assisted grinding of Al2O3 ceramics - Chatter vibration suppression using fixed superabrasive polishing stone - Free abrasive finishing of internal channels with different cross-sectional geometries - High-quality machining of cemented carbide using PCD ball end mills - Fixed-abrasive machining with magnetic brush for Ti-6Al-4V ELI alloy - High-efficient polishing of polymer surfaces using catalyst-referred etching This issue will provide an understanding of the recent developments in abrasive technologies, leading to further research. We deeply appreciate the careful work of all the authors, and we thank the reviewers for their incisive efforts. [ABSTRACT FROM AUTHOR]

Molecular dynamics simulation is used to simulate the polishing process of silicon in this paper. Several models such as single abrasive and multi-abrasive are established for simulation analysis. The results show that the greater the height difference between the double abrasives, the greater the polishing force in the machining process, resulting in higher surface bulge and deeper underground damage after polishing. When polishing with a single abrasive, the polishing depth plays a dominant role in the changes in polishing force, temperature and coordination number. When multiple abrasives are arranged at a certain angle, the force effect and damage distribution are more complex because of the coupling effect of abrasives. Due to the effect of multiple abrasives, the heat between abrasives cannot be dissipated in time. As a result, the temperature of multiple abrasives polishing at a certain angle is higher than that of the other two cases (single abrasive and double abrasives). [ABSTRACT FROM AUTHOR]

This paper presents an experimental study of abrasive waterjet turning of an extrusion aluminum alloy (AlMg0,7Si). The aim of the paper is to determine differences of two methods from the point of view of machined surface quality and the depth of penetration, i.e., the diameter of the parts after the turning process. During the experiments, the traverse speed of the cutting head and the rotation of the turned parts were changed, other parameters, like pressure of the water, abrasive mass flow rate were kept constant. Diameter and some surface roughness parameters of the test parts were measured after the machining. On the base of experimental results, advantages, and disadvantages of two methods are explained in the paper. [ABSTRACT FROM AUTHOR]

The quality of the inner surface of the elbow used by common types of engines has a serious impact on its performance. In order to improve the machining accuracy of the inner surface and enhance the uniformity of the whole structure, large eddy simulation is carried out for the flow channel in an S-shaped elbow with the abrasive flow by using KET subgrid model. The distribution of flow field, vortex formation law, and the influence of the vortex in the process of polishing surface quality are analyzed, and the processing experiment is carried out. The numerical simulation result shows the inlet pressure determines the inlet velocity of abrasive particle flow. Higher inlet pressure will significantly increase the shear force, improve the uniformity of turbulence kinetic energy distribution on the elbow wall, and increase the number of abrasive flow vortices. The experiment result shows the changes in inlet pressure and abrasive particle size have a significant effect of the polishing effect on S-shaped elbow. The combination of coarse abrasive and high inlet pressure will produce an over-polishing phenomenon, the inner surface roughness of the elbow can be reduced to 76 nm, and the optimal process parameters determined by the experimental research can achieve the uniform polishing of the S-shaped elbow by the abrasive flow machining technology. [ABSTRACT FROM AUTHOR]

Increasing demand and resource overuse has prompted the exploration of spent secondary materials as a primary raw material for a variety of applications, leading to a more sustainable environment. Spent electric grid ceramic insulator, one of the waste materials of ceramic industry, has a good hardness and strength. It can be reused as value-added material in the Abrasive Water Jet Machining (AWJM) industry. The present work deals with the generation of cost-effective replacement material for abrasive water jet machining from electric insulator rejects (EIR). Mechanical crushing method is opted to generate the abrasive grit for the machining process. Grit generation pattern and the friability of the electric insulator rejects were determined experimentally. The results indicate that the friability of the processed electric insulator rejects is comparable with the commercially available garnet abrasive. Geometric parameters such as sphericity, elongation ratio, and shape factor for the processed electric insulator rejects were studied using scanning electron microscopy. The machining performance indicators for standard aluminium material such as volume of material removal, kerf angle, surface roughness, and cutting width were measured for electric insulator rejects and compared with existing garnet abrasive grain. The experimental results of the newly generated electric insulator reject abrasive were compared with the performance indicators of the garnet abrasive. The observed deviation was lower proving that it can be used as an alternative abrasive in the abrasive jet machining process. Cost analysis and recycling ability predict the economical usability of the newly generated abrasives. [ABSTRACT FROM AUTHOR]

3D printing has been widely used in the micromachining fields due to its flexibility in design and fabrication. However, due to the presence of undulations on the surface of the finished part, the 3D printing has hardly been employed in the optics manufacturing. In this study, we propose a manufacturing method for optical splitters based on 3D printing and microfluidic abrasive machining. We simulate the effect of microfluidic abrasive machining on microchannels, that helps mitigate the impact of undulations. The 3D printed optical splitter using microfluidic abrasive machining presents high efficiency in optical propagation and high uniformity. We believe that the 3D printing accompanied with microfluidic abrasive micromachining would be a promising technique in the optics manufacturing fields. [ABSTRACT FROM AUTHOR]

Traditionally, photolithography and soft-lithography methods have been used to fabricate micro-molds for casting polymeric microfluidic chips. Because of the time and cost involved, there has been motivation to fabricate microfluidic micro-molds using other techniques. A previous study utilized stainless steel masks cut using abrasive waterjet micro-machining (AWJM) together with abrasive slurry jet micro-machining (ASJM) to mill micro-molds in Al6061 which would allow casting of polymeric microfluidic chips with intersecting micro-channels. However, the deflected slurry jet from the mask edge struck the substrate at oblique incidence and led to two undesirable effects: a trench along the edges of the raised structures representing the channels, and an undercut of the mask. Both effects were linked to the propensity for ductile materials to erode more rapidly at oblique incidence than perpendicular. The present paper demonstrates that these effects can be greatly reduced by using AWJM to create molds in more brittle materials which erode in the opposite fashion, i.e., more rapidly at perpendicular than oblique incidence. To demonstrate this, AWJM was used to machine masks from aluminum oxide and subsequently mill micro-molds with raised intersecting free-standing structures into aluminum oxide substrates. It was found that for molds of identical depth, the undercut and the undesirable erosion in aluminum oxide molds could be reduced by five and four times, respectively, when compared to molds machined in Al6061 using the previous AWJM/ASJM hybrid technique. It was also found that much deeper molds containing intersecting raised free-standing structures of up to 435 μm in height could be made in aluminum oxide, while still maintaining an acceptable surface quality (1.51 μm Ra and 2.47 μm Wa), undercut (25 μm), and undesirable erosion (3%). Finally, since the technique involved only AWJM, it was much more convenient than the previously utilized hybrid AWJM/ASJM. • AWJM used to fabricate novel micro-molds with free-standing structures in alumina. • Effect of process parameters on the surface quality and shape of the structures was studied. • Mold quality was improved compared to previous AWJM/ASJM method for metals. • Using the optimum parameters, molds were fabricated and microfluidic chips cast. [ABSTRACT FROM AUTHOR]

In the abrasive belt grinding process, actual material removal is an important parameter that affects its accuracy. At present, for obtaining the actual material removal, offline measurements are required to establish the mathematical prediction model. To improve the accuracy and efficiency of abrasive belt machine grinding, this paper proposes a novel method for monitoring material removal using multiple sensors and a two-dimensional (2D) convolutional neural network (2D-CNN) learning algorithm. In this method, features of multiple types (color, texture, and shape) are extracted from vision signals, and that of multiple domains (time, frequency, and time–frequency domain) are extracted from sound and tactile signals. These features are constructed into a 2D feature matrix as the input model, and the 2D-CNN prediction model is established between the multisensor features and the material removal rate of the abrasive belt grinding process. An experimental dataset is used to train and verify the established model. The results show that the proposed method can identify that sensor signals are sensitive to the material removal rate. After optimizing and tuning the model parameters, the coefficient of determination of the prediction results is as high as 94.5% and the root mean square error is 0.017. Therefore, the proposed method can be employed for the prediction of material removal rate for different belt specifications and different grinding parameters. Compared to traditional machine learning methods, this method can yield better training results without feature selection and optimization. [ABSTRACT FROM AUTHOR]

During the wafer fabrication procedure, abrasive machining occupies a large proportion in time and economic cost, mainly including grinding, lapping, and polishing. The third-generation semiconductor materials, represented by SiC, have the properties of high hardness, large brittleness, and strong chemical inertness, which make abrasive machining more challenging. To improve the machining efficiency and quality, this paper applied the smoothed particle hydrodynamics (SPH) method to simulate the machining behavior of single abrasive grain for SiC wafer. The micro-mechanical mechanisms of the main influencing parameters, such as velocity, depth, and angle, were studied in abrasive machining for SiC wafer. First, it is proved that using SPH coupled with a finite element to study the mechanical effects of abrasive machining for SiC wafer is a feasible and useful method. Then, the explanations for the beneficial effects of ultrasonic vibration-assisted machining, high-speed machining, and other abrasive machining are provided through the analysis of the simulated results. In addition, the optimization basis for parameters such as scratching velocity, scratching depth, and ultrasonic vibration frequency is obtained. This research provides a good insight into implying the micro-mechanical mechanisms of abrasive machining and achieving the optimization for the abrasive machining of hard-brittle wafer materials, which help avoid the shortcomings of experimental research and produce economic benefits. [ABSTRACT FROM AUTHOR]

Recently, a novel corrosion-resistant construction material, Carbon Concrete Composite (C3), consisting of coated carbon fibers embedded in a concrete matrix, was introduced. However, thermal exposure during domestic fires may impact the release of organic pollutants and fibers during abrasive processing and/or demolition. Consequently, the objective of this study was to explore the emission characteristics of toxic compounds and harmful fibers during the dry-cutting after exposure to 25–600 °C (3 h, air). These parameters mimic the abrasive machining and dismantling after a domestic fire event. Mass spectrometry and chromatography served as analytical methodologies, and no organic pollutants for exposure temperatures ≥ 400 °C were found. In contrast, significant amounts of pyrolysis products from the organic fiber coating were released at lower temperatures. Studying the morphology of the released fibers by electron microscopy revealed a decrease in fiber diameter for temperatures exceeding 450 °C. At ≥550 °C, harmful fibers, according to the World Health Organization (WHO) definition, occurred (28–41 × 103 WHO fibers/m3 at 550–600 °C). This leads to the conclusion that there is a demand for restraining and protection measures, such as the use of wet cutting processes, suction devices, particle filtering masks and protective clothing, to handle thermally stressed C3. [ABSTRACT FROM AUTHOR]

Titanium alloy (Ti–6Al–4V) is one of the important alloys in titanium series used in various parts of the aerospace industry. The aim of this work is to investigate the effect of process parameters on Ti–6Al–4V to improve the machining, surface, and geometric characteristics of the circular cut profile by determining the optimum parameters for the abrasive waterjet machining (AWJM). The input parameters considered are the abrasive flow rate (AFR), stand-off distance (SOD), and traverse speed (TS). Output parameters like circularity, cylindricity, and surface roughness (SR) of the circular cut are evaluated. The experiments are conducted based on central composite design (CCD) in the response surface methodology (RSM). In this work, a new machining strategy has been reported for circular path cutting with start point at the center and end point at the perimeter. It is found that the circularity increases with the increase in TS and SOD, cylindricity increases with an increase in AFR, and TS and SR decrease with the increase in AFR and TS. Confirmation tests with optimum levels of parameters have been done to determine the adequacy of RSM. In addition to that, the cutting profiles are also analyzed using scanning electron microscopy (SEM) and Steinbichler Comet 3D Blue Light Scanner. It is found that the wear tracks, groove formation, plowing deformation, and embedded abrasive particles on a circular profile are minimized with the optimum parameter levels. Atomic force microscopy (AFM) is used to verify the minimum SR value of 119.252 nm in AWJ-machined surface. [ABSTRACT FROM AUTHOR]

With the development of science and technology, many precision fields have higher requirements for the machining quality and precision of hard and brittle materials. Brittle materials such as glass and ceramics have fragile physical properties, resulting in poor stability during machining. Ultrasonic vibration-assisted polishing (UVAP) is suitable for machining various brittle materials and can well solve the machining problems caused by the characteristics of brittle materials. In order to ensure the machining quality, a polishing force model of K9 optical glass for different processing parameters is established in this paper. The new model mainly considers the following aspects: (1) Considering the randomness of shape, the truncated polyhedral model is used to model the abrasive particles. (2) Based on the fractal theory and mathematical statistics, a microscopic morphology model of the polishing tool is established. (3) Based on the N–S equation, a polishing force model considering the micro-contact states of the polishing tool, abrasive particles, and workpiece is established. By comparing with the experimental results, the new model has high accuracy in predicting the polishing force. The new model and results lay the foundation for the subsequent research of brittle materials. [ABSTRACT FROM AUTHOR]