Material Removal Mechanism Research Articles

Microstructural characteristics with process-microstructure-property relations during high-frequency ultrasonic vibration-assisted cutting of metallic material

Microstructural characteristics of chips and machined surfaces are influenced by the multiphysics fields distribution. This study investigates the multiphysics-induced microstructural deformation behaviors of CuZn37 metallic alloy during high-frequency ultrasonic vibration-assisted cutting (HFUVAC) and conventional cutting (CC). One the one hand, the multiphysics field distribution was established to clarify the chip formation of cutting characteristics and transient deformation process. The multiphysics field distribution of HFUVAC exhibited periodic changes due to tool intermittent movement, resulting in reduced cutting temperature and force. This intermittent movement also enhanced the sharpening shear effect due to instantaneous impact stress, transitioning from fragmented quasi-shear strain to continual multiple-shear strain during chip formation. One the other hand, the microstructural changes were examined to explain material removal mechanisms. The microstructure of CC demonstrated grain refinement and dislocation slip induced by friction and significant shear deformation. The microstructure of HFUVAC revealed the formations of dynamic recrystallization, twinning structures, and stacking faults, which were associated with enhanced plastic activity and limited slipping due to high-frequency impacts. The work reveals the response of the workpiece microstructure under the composite effects of high-frequency impacts and cutting process, which provides theoretical basis for the microstructure modification design through cutting technology.

Recent Developments in Mechanical Ultraprecision Machining for Nano/Micro Device Manufacturing.

The production of many components used in MEMS or NEMS devices, especially those with com-plex shapes, requires machining as the best option among manufacturing techniques. Ultraprecision machining is normally employed to achieve the required shapes, dimensional accuracy, or improved surface quality in most of these devices and other areas of application. Compared to conventional machining, ultraprecision machining involves complex phenomenal processes that require extensive investigations for a better understanding of the material removal mechanism. Materials such as semiconductors, composites, steels, ceramics, and polymers are commonly used, particularly in devices designed for harsh environments or applications where alloyed metals may not be suitable. However, unlike alloyed metals, materials like semiconductors (e.g., silicon), ceramics (e.g., silicon carbide), and polymers, which are typically brittle and/or hard, present significant challenges. These challenges include achieving precise surface integrity without post-processing, managing the ductile-brittle transition, and addressing low material removal rates, among others. This review paper examines current research trends in mechanical ultraprecision machining and sustainable ultraprecision machining, along with the adoption of molecular dynamics simulation at the micro and nano scales. The identified challenges are discussed, and potential solutions for addressing these challenges are proposed.

Experimental study on ultrasonic vibration‐assisted drilling performance of carbon fiber polyetherketoneketone laminate

AbstractParts made from carbon fiber reinforced polyetherketoneketone (CF/PEKK) primarily use mechanical connections during assembly, where the quality of hole processing directly impacts the connection strength. However, defects like delamination, burrs, and fiber pull‐out frequently occur during drilling. While existing research focuses on optimizing conventional drilling (CD) and helical milling (HM), ultrasonic vibration‐assisted drilling (UVAD) shows superior performance in reducing thrust force and defects. This study experimentally evaluates the hole‐making performance of CF/PEKK using the UVAD method. It examines the effects of ultrasonic vibration on thrust force, drilling temperature, processing damage, chip morphology, and surface microstructure, and discusses the damage suppression mechanism. The results show that the UVAD method significantly reduces thrust force and drilling temperature compared to the CD method, with similar trends in delamination and burr damage. This study demonstrates that using the UVAD method for drilling CF/PEKK laminates effectively reduces thrust force, drilling temperature, and machining damage, thereby significantly improving processing quality. The material removal mechanism of UVAD was analyzed, offering substantial insights and practical guidance for the efficient drilling of CF/PEKK laminates.Highlights The drilling performance of CF/PEKK was studied. The drilling quality of UVAD and CD is compared by experiments. UVAD has a lower thrust force and drilling temperature. UVAD can reduce machining damage and improve machining quality.

Temperature field in the crack-free ductile dry grinding of fused silica based on wheel wear topographies

Fused silica is an excellent window material widely used in ultraviolet transmission optical system. Crack-free ductile dry grinding is a novel method for the efficient fabrication of fused silica. The grinding temperature field has an important influence on the grinding process. However, most previous studies assumed that the grinding temperature was independent of the wheel’s wear. In this paper, a temperature field model of the ductile dry grinding of fused silica is developed based on wheel wear topographies. Simulated wheel topographies with the same statistical parameters as the realistic wheel wear topographies are reconstructed based on the convolution filtering and Johnson transformation algorithm. The theoretical temperature field is the superposition of the thermal effects induced by effective cutting grain point heat sources extracted from the simulated wheel topographies. The theoretical prediction accuracy of the wheel-workpiece contact zone is validated by an infrared radiation transmission method. This model not only provides opportunity to explore the material removal mechanisms and improve the surface generation quality of fused silica during the wear process of the wheel, but also could be extended to provide the basis for the utilization of grinding heat or prevention of grinding thermal damage for other isotropic materials.

Controllable diamond cutting of structured surfaces with subnanometric height features on silicon

Diamond cutting with a controllable depth of cut at the subnanometric scale is desired for next-generation electronics and optics. However, due to the limits of positioning accuracy of the current machine tools, diamond cutting at subnanometric scale depths remains in realm of molecular dynamic (MD) simulations instead of engineering realization. Cutting force feedback and control is regarded as a potential method to improve the positioning accuracy of machine tools. In this study, an ultra-precision force feedback loop with the resolution down to submillinewton is employed and integrated on an ultra-precision machine tool to enable the capability of cutting at subnanometric scale depth. By this way, the relationship between the cutting force and such small depth of cut needs to be well studied. MD simulations are conducted in this study to analyze the mechanism of material removal and influence of the crystallographic effect on the actual cutting depth and force caused by varied cutting directions at subnanometric to nanometric scale depth in diamond turning. Then, the crystallographic effect of silicon with the depth of cut from subnanometric to nanometric scale is compensated experimentally for accurate cutting at such an extremely small scale. Controllable diamond cutting of structured surfaces with actual depths and amplitudes ranging from several angstroms to a few nanometers on silicon is successfully realized.

Comprehensive Review on Research Status and Progress in Precision Grinding and Machining of BK7 Glasses.

BK7 glass, with its outstanding mechanical strength and optical performance, plays a crucial role in many cutting-edge technological fields and has become an indispensable and important material. These fields have extremely high requirements for the surface quality of BK7 glass, and any small defects or losses may affect its optical performance and stability. However, as a hard and brittle material, the processing of BK7 glass is extremely challenging, requiring precise control of machining parameters to avoid material fracture or excessive defects. Therefore, how to obtain the required surface quality with lower cost machining techniques has always been the focus of researchers. This article introduces the properties, application background, machining methods, material removal mechanism, and surface and subsurface damage of optical glass BK7 material. Finally, scientific predictions and prospects are made for future development trends and directions for improvement of BK7 glass machining.

Study on ultra-precision diamond cutting of polymers: Factors affecting dimensional accuracy and material removal mechanism

Polymers with surface microstructure have promising prospects for applications in the domains of aerospace, integrated circuits, and optical engineering. Ultra-precision cutting has unique advantages in the preparation of microstructure with high precision and complex shape. However, the inherent characteristics of polymers such as high elasticity, strong toughness, and poor thermal conductivity bring ultra-precision cutting a great challenge. In this study, the rectangular groove microstructures on polymers were fabricated by ultra-precision diamond cutting, and the influence of matrix material, feedrate and cutting depth on cutting performance and dimensional accuracy was quantitatively evaluated. The results indicate that the polyimide (PI) exhibits a good machinability compared with polyetheretherketone (PEEK) and polytetrafluoroethylene (PTFE). In addition, the feedrate have a negligible influence on the morphologies and dimensional accuracy of groove structure, while the groove width decreases and the ridge width increases as the cutting depth increases from 10 μm to 100 μm. The groove structure has the best dimensional accuracy when the cutting depth is 10 μm. Furthermore, the material removal mechanism of PI was discussed detailedly based on the results of numerical simulation and experiment.

In situ x-ray imaging to understand subsurface behavior during continuous wave laser drilling

A limited understanding regarding the underlying dynamics and mechanisms of material removal during continuous wave laser drilling has presented significant challenges in achieving precision and process control. To address this, we employed high-fidelity, in situ synchrotron x-ray imaging to reveal previously unknown material behaviors during continuous wave laser drilling with power modulation. Our findings highlight that high-aspect ratio drill holes are achieved when the laser modulation frequency falls within the range of 8–12 kHz, provided that the laser average power and modulation amplitude levels meet the specified limits. Under these conditions, we identified a material removal mechanism driven by incremental accumulation of recoil pressure that gradually pushes material upward from deep within the substrate to the surface. This mechanism manifested as a low-frequency fluctuation in the vapor depression depth, resulting in periodic instances of material ejection. Furthermore, our study underscores that rapid expansion of the melt pool and the widening of the drill hole opening can impede effective material removal by redirecting energy from material ejection to increasing the melt pool size. This investigation contributes essential insights into the subsurface dynamics involved in the drilling of high-aspect ratio holes, furthering our fundamental understanding of this intricate process.

Effect of Friction on Critical Cutting Depth for Ductile–Brittle Transition in Material Removal Mechanism

Abstract The material removal process takes place due to phenomena such as plastic deformation and brittle fracture. A long continuous chip is formed when the plastic deformation dominates, whereas a fracture-induced discontinuous chip is formed when the brittle fracture dominates. The means of material removal changes at a certain cutting depth for a particular material, the so-called transition depth of cut (TDoC). This article aims to predict the TDoC while including the effect of friction between the tool and workpiece. We propose a modification to a recently developed model (Aghababaei et al., 2021, “Cutting Depth Dictates the Transition From Continuous to Segmented Chip Formation,” Phy. Rev. Lett., 127(23), pp. 235502) to incorporate the effect of friction. The model predicts a transitional depth of cut as a function of tool geometry, material properties, and friction. The model is supported by performing orthogonal cutting experiments on different polymers such as polymethyl methacrylate (PMMA), polyoxymethylene (POM), and polycarbonate (PC). The model is also compared with existing models in the literature, where an improvement in the prediction of TDoC is shown. Moreover, the effect of the friction coefficient and rake angle on the TDoC is discussed. The results show that transitional cutting depth is reduced by increasing the friction coefficient. Alternatively, the TDoC reaches its maximum at an optimum rake angle, which is a function of the specific material being cut. The model aids in accurately predicting the TDoC, a crucial factor for optimizing various material removal processes.

Evaluation of the machinability and enhancement of biological response of ZTA-based 13-93 bio-glass composite materials

Besides the exceptional mechanical and biocompatible properties, zirconia toughened alumina (ZTA) has limited biomedical applications due to its bio-inertness properties. The present work examines the effect of 13-93 bio-glass (BG) addition on the machinability and biological responses of ZTA-containing BG composites. The ZTA–xBG (x = 0, 5, 10, 15, and 25 wt%) composites have been synthesized and sintered at 1250°C for 4 h. The machining of composite samples is done on an abrasive air-jet machine (AAJM), and their machinability is studied in terms of surface roughness (SR), material removal rate (MRR), and mechanics of material removal (MMR). The result indicates that MRR decreases and SR enhances with the addition of BG. The MMR is studied using machined surface morphology, and the results confirm that material removal is due to the large erosion crater. The relative density is decreased with enhancing the BG content except for a sample containing a high amount of BG (25 wt%). Mechanical properties such as hardness and flexural strength are enhanced by BG content up to 25 wt%. In-vitro analysis in simulated body fluid (SBF) reveals that both corrosion and bioactivity increase as BG concentrations increase. According to the in-vitro cell culture data, adding BG to ZTA improves cellular viability with BG content up to 25 wt%. The antibacterial result shows that the viability of the bacterial cells on the composites has significantly decreased with BG content. As a result, biomaterials with this architecture may be used as bone implants.

Effects of Ar ion bombardment on the structure and properties of β-quartz

β-quartz is an important component that affects the physical and chemical properties of glass-ceramics. The material removal process of ion beam machining is complicated as one of the ultra-precision machining forms. Therefore, it is important to understand the removal mechanism of ion beam machining materials. The methods of molecular dynamics (MD) and first-principles were adopted to investigate the microscopic mechanism of ion beam bombardment of the β-quartz structure. The damage evolution of structures and the evolution of material properties caused by defects respectively from the atomic and electronic levels. Through MD analysis, we find that the random collision between incident ions and matrix atoms can lead to the formation of sputtered atoms. The incidence of ions will increase the disorder degree of the matrix, and the influence on the disorder degree at different depths of the matrix is different. The degree of disorder increases obviously in the range of 50–70 Å from the surface of the matrix. It has a significant impact on the surface topology of the matrix, the number of defects, surface roughness, and matrix density. The results of first-principle calculation show that the refraction, absorption and other characteristics of the system are significantly different with different doping forms, and the energy loss is most affected by substituted doping. And the substituted doping defects have the most significant effects on the structural energy loss. Among, the Ar-substituted O doping structure leads to higher energy loss, and the peak energy loss intensity reaches 5.146. In contrast, the Ar-substituted Si doping structure causes the least energy loss, the intensity is 2.543. This study provides a theoretical basis for the selection of parameters and the realization of ultra-smooth surface in actual ion beam machining.

Unveiling superior chemical mechanical polishing properties of a novel shell-core structure: Insights from an atomic-scale perspective

The precision polishing process plays a crucial role in the modern advanced semiconductor manufacturing field, making it imperative to develop excellent polishing abrasives through new techniques. In this study, we obtained well-defined spherical nano-composite polishing particles CeO2@SiO2 via posterior grafting synthesis, which have a clear core–shell structure and exhibit a high Ce3+ concentration. Atomic force microscopy revealed significant improvement in surface roughness of the abrasives on Si substrates, achieving the material removal rate (MRR) of 300 nm/min. MRR is closely correlated with the Ce3+ concentration. Combining aberration-corrected transmission electron microscopy with first-principles calculations demonstrated that surface oxygen vacancies and interfacial charge transfer were the primary origins of high Ce3+ concentration, and revealed the material removal mechanism. This work not only provides new insights into the process but also offers new routes for the development of novel polishing abrasives in the future.

Investigation on scratching force and material removal mechanism in scratching of fiber-reinforced resin matrix composites considering the effect of temperature

Investigation on scratching force and material removal mechanism in scratching of fiber-reinforced resin matrix composites considering the effect of temperature

Mechanochemical grinding with aluminium-coated nickel and diamond mixed abrasive vitrified bond wheel for reducing anisotropy in (100) surface single-crystal diamond processing

While single-crystal diamond is a promising wide-bandgap semiconductor material, it is also the hardest material in nature and exhibits remarkable anisotropy, presenting a challenge for high-quality and efficient processing. To address this issue, this article introduces a method that utilises aluminium-coated nickel and diamond mixed abrasive vitrified bond grinding wheels for a mechanicochemical grinding process to reduce the anisotropic removal of diamond. Different cutting depths, abrasive ratios, grinding directions, and linear velocities were employed in the processing, with the material-removal mechanism studied through morphological characterisation, elemental content, and other detection methods. The experiment revealed that the catalytic effect of nickel metal occurred along the (111) crystal plane of the diamond. This catalytic process involves a transition from sp3 diamond to amorphous carbon, followed by graphitisation. The spin-rotating mechanicochemical grinding process mainly involves plastic removal in the soft direction and coupled chemical and mechanical removal in the hard direction. Employing this method reduced the surface roughness of the 7 × 7 mm as-grown crystal to Ra 0.467 nm, with a material removal rate of 4.73 μm/h, achieving a nearly damage-free machining surface.

Machining of Ox-Ox (Al2O3/Al2O3) ceramics matrix composites by ultrafast laser

High-performance Ox-Ox ceramics material composites (CMC) are a strategic building block in the aerospace industry and high-temperature applications. The ceramics material composites are hard to machine due to high hardness, fracture toughness, and heterogeneous structures. Furthermore, it is prone to brittle fracture during the machining process. In this study, we successfully demonstrate ultrafast laser machining technology to machine Ox-Ox CMCs. A picosecond laser has been used to machine slots to understand the impact of laser process parameters on the material removal mechanism by performing deep machining. Different scan rates and a number of over-scans have been employed to understand the material removal mechanism, which is dominated by laser ablation and aided by melting due to the residual surface temperature. The maximum material removal rate of 21.75 mm3/min has been achieved for the scan rate of 300 mm/s. This can be related to the reduction in the ablation threshold and the critical balance between the material removal mechanism by ablation and melting. It was found that, the surface roughness of the cut surface has decreased due to melting and solidification. The cross-sectional examination reveals two distinct surface structures, which are entirely resolidified and thermally eroded regions.

Scratching properties of 4H–SiC single crystal after oxidation under different conditions

Single-crystal silicon carbide (SiC) has poor machinability because of its low fracture toughness, and surface modification has become the first choice for SiC polishing to obtain a high removal rate and a smooth surface. However, the removal mechanism of SiC after modification remains unclear. In this study, diamond scratching experiments were performed on 4H–SiC after oxidation under two conditions. To reveal the material removal mechanism, the scratch morphology and subsurface defects were analysed using Raman spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, and transmission electron microscopy. The results showed that oxidation improved the scratch depth and critical depth for ductile removal, resulting in a smooth scratch surface with low damage. However, weak oxidation increased the median crack length and exacerbated the subsurface damage. The SiOxCy, C = O, C–O–C, and Si–O–Si functional groups produced during oxidation reduced the hardness and improved the machinability of the 4H–SiC substrate. On the other hand, strong oxidation reduced the generation of surface cracks, tearing, and spalling, and weakened the propagation of subsurface median cracks. These results prove that ultrasonic-assisted photocatalytic oxidation provides high removal efficiency and defect control, providing a new approach for the synergistic polishing of SiC substrates.

Experimental study on slurry erosion wear behaviour of 2205 duplex stainless steel through integrated Taguchi approach and artificial neural network

Slurry erosion due to particle entrainment poses a significant threat to slurry handling components, leading to reduced performance and shorter service life. The ferritic-austenitic microstructure of 2205 duplex stainless steel (DSS) offers resistance to erosion and corrosion in harsh environments. This study investigated the slurry erosion wear response of 2205 DSS, focusing on parameters, such as: angle of impingement, impact velocity, slurry concentration, erodent size, and stand-off distance. A Taguchi experimental design approach, along with analysis of variance (ANOVA), was employed to design the experiments and identify the most significant factors. ANOVA results revealed that impact velocity and slurry concentration were the most influential parameters affecting mass loss, while erodent size and impact velocity significantly influenced surface roughness. Additionally, an artificial neural network model was used to estimate output responses, and the model's predictions were compared with experimental results. The surface and sub-surface characteristics of the eroded samples were analysed using X-ray diffraction, microhardness testing, and optical profilometry. The material removal mechanisms were studied using scanning electron microscopy, revealing ductile erosion behaviour in 2205 DSS. Micro-cutting, ploughing, lip formation, and indentation were identified as the primary methods of material removal in 2205 DSS.

Enhancement of acoustic cavitation streaming: A study on surface finishing of additively manufactured components

Due to the poor surface characteristics of additively manufactured parts, the necessity for post-process surface enhancement is crucial. Among the prevalent post-processing techniques, the acoustic cavitation-based surface finishing technique has recently emerged. Despite a considerable amount of focused research on the material removal mechanisms of this technique, less attention has been devoted to addressing its limitations associated with enhancing the process capability towards achieving a better surface finish. The driving force behind the acoustic cavitation technique is the bubble implosion through cavitation streaming, and the cessation of the acoustic cavitation streaming beyond a certain length is the main limitation. It has restrained the process capability towards finishing both external and internal surfaces. Hence, this research aims to unravel novel ways of employing the acoustic cavitation-generating parameters and achieving better-quality surface finishing of additively manufactured (AM) components. A study has been conducted on different AM materials, including Inconel 625 and aluminum alloy, by introducing various methods associated with acoustic amplitude, working mediums, temperature, and external vibration. The results reveal a significant reduction in average surface roughness for both materials. The topographical and morphological observations confirm the qualitative improvement on the surfaces. In addition, the conical bubble structures that frame the acoustic cavitation streaming are elucidated by implementing high-speed imaging techniques, and their enhancement at different parametric conditions is delineated. Henceforth, the findings suggest a notable insight into the potential of the employed approaches in enhancing the acoustic cavitation streaming for achieving a better surface finish of AM components.

Removal mechanism of double-diamond-abrasive-grinding GaN single crystals under graphene lubrication

Gallium nitride (GaN) is an advanced material used to manufacture chip wafers and high-power devices. Recently, grinding processing, has been applied in the fields of machinery manufacturing, aerospace, and medical devices as a highly efficient machining method. An in-depth understanding of the material removal mechanism produced by the double-grinding processes can provide guidance for the design of GaN-based nanodevices. Herein, molecular dynamics simulations were used to investigate the mechanism of removal of double-diamond-abrasive-grinding gallium nitride crystals under graphene lubrication, and a systematic study was performed to investigate the involved surface morphology, grinding force, stress distribution, and subsurface damage behavior. Results reveal that graphene can substantially enhance the wear resistance of GaN substrates by reducing surface wear, atomic displacement., potential energy, and subsurface damage, thereby playing a protective role toward the substrate. As the grinding depth increases, the grinding force and subsurface damage depth also increase. Furthermore, the effects of abrasive grain spacing on subsurface damage depth and phase change atoms were analyzed and found to have limited influence on material removal efficiency. These results deepen our understanding of material removal and protection mechanisms relative to substrates resulting from double-grinding processes as well as offer valuable insights for the rational design of abrasive wheels.

Machining performance and material removal mechanism of sapphire with novel polishing slurry

Enhancing the interfacial reactivity of polishing slurry is crucial for improving the polishing efficiency and surface quality of sapphire wafers. In this study, a novel green polishing slurry was developed, comprising aminomethyl propanol, xylitol, highly active silica, and deionized water. The processing quality and removal mechanism of this novel green polishing slurry on semi-solid flexible polishing were investigated to achieve ultra-precision, high-efficiency, and environmentally friendly polishing of sapphire wafers. Experimental results demonstrated that the novel green polishing slurry reduced surface roughness by 12.5% and increased the material removal rate by 71.3% compared with traditional polishing slurry. Various analytical techniques, including wear debris analysis, molecular simulation, infrared detection, electrochemical testing, and physical phase detection, were utilized to explore the material removal mechanism. The findings indicated that aminomethyl propanol promotes chemical reactions between the green polishing slurry and sapphire wafers, leading to the conversion of the intermediate product Al(OH)3 to Al(OH)4-. In addition, the complexation reaction between xylitol and Al(OH)4- ions during polishing was found to accelerate the removal of surface materials from sapphire wafers, resulting in improved polishing efficiency and surface quality.