Material Removal Mechanism Research Articles

Investigation on 2D SiCf/SiC composite scribing mechanism by single- and double-grit

To validate the proposed removal mechanism of 2D SiCf/SiC composite, single- and double-grit scribing experiments were conducted on the fiber woven surface (WS) and stacking surface (SS) along the 0°, 45°, and 90°. The results indicate that transverse fibers mainly undergo shear, tensile, and bending fractures. The removal modes of normal fibers are shear and bending fractures. The longitudinal fibers are damaged by tensile (cut-in side) and bending (cut-off side) fractures, accompanied by fiber peel-off. The removal forms of the matrix include crack propagation, ductile scratch, powdery removal, and brittle peel-off. The order of scribing force is FSS0 > FWS45 > FSS90 > FWS0. The maximum and minimum scribing force occur on SS0 and WS0, respectively, due to the powdery removal of matrix and fibers + matrix peel-off. The 2nd grit scribes the matrix layer and fiber tip in a very low depth to cause powdery and ductile removal, which exhibit the different material removal mechanism with the 1st grit. The scribing damage formed by 1st grit greatly reduces the force required by the 2nd grit for the same material removal volume. The coupling effect among grits in multi-grit scribing and grinding cannot be ignored.

Characterization of ultrasonic vibration and polishing force in sapphire ultrasonic vibration-assisted flexible polishing: Insights from in-situ monitoring systems

Sapphire ultrasonic vibration-assisted flexible polishing (UVAFP) is a promising technique for comprehensively improving the surface integrity of machined parts. The technique was performed on an ultra-precision machine tool with the in-situ monitoring systems in this paper, which aims to provide a new perspective for understanding the material removal mechanisms in the sapphire UVAFP process. A Taguchi L9 (43) orthogonal experiment was conducted to investigate the effects of feed distance, spindle speed, ultrasonic vibration (UV), and polishing time on the surface finish and material removal in the process. In addition, the effect of a polyurethane ball tool is not trivial. A single-factor experiment was conducted for exploring it. Based on a laser displacement measurement system and an acoustic emission sensor system, the characteristics of time-dependent ultrasonic amplitude and ultrasonic frequency for the sapphire UVAFP system were analyzed, with the effectiveness of UV demonstrated. Based on a three-component force measurement system, the characteristics of normal force and its relationship with process parameters and tool deformation were analyzed, with macro- and micro-level examined. In conclusion, this paper presents the characterization of UV and polishing force in the sapphire UVAFP process, providing novel insights into understanding the material removal mechanisms of sapphire and even more manufacturing problems.

Synthesis and characterization of Fe3O4@SiO2 core-shell nanoparticles for mirror and efficient magnetic compound fluid polishing of TC4 titanium alloy

To fully investigate the polishing performance of the Fe3O4@SiO2 core–shell abrasive for TC4 titanium alloy plate and solve the problem of uneven distribution of abrasive particles in magnetic compound fluid polishing (MCFP) and obtain ultra-smooth titanium alloy surface. In this paper, the functional Fe3O4@SiO2 core–shell abrasives were prepared and characterized by XRD, FTIR, VSM and TEM to demonstrate the successful encapsulation of SiO2 in Fe3O4 first. Second, a new polishing device was built to perform polishing experiments. Four different fractions of Magnetic compound fluid (MCF) were configured and utilized in polishing experiments for MCFP of TC4 titanium alloy to verify the polishing properties. Finally, the contact model between abrasive particles and workpiece is established and the material removal mechanism is discussed. The results show that SiO2 was successfully coated on Fe3O4. The polishing results show that the MCF containing the core–shell structure had the best polishing effect. The surface roughness Ra decreased from 0.201 μm to 0.025 μm after 20 min of polishing. The surface roughness of TC4 titanium alloy with an initial roughness Sa of 0.248 μm is reduced to 0.023 μm after polishing by Fe3O4@SiO2 core–shell abrasive. It is shown that the application of core–shell abrasive to process titanium alloys can obtain smooth and defect-free surfaces with good polishing performance. The surface quality of titanium alloy can be improved effectively by using core–shell abrasive, and a new idea for polishing titanium alloy is proposed. This study plays an important role in solving the problem of uneven particle distribution in MCFP. These results pave the way for further research into the application of core–shell abrasives in precision machining and expand the application scope of particles with core–shell structure.

Roughness control in the processing of 2-inch polycrystalline diamond films on 4H-SiC wafers

Diamond is an essential material for the manufacture of semiconductors devices, infrared optical windows, heat dissipation and other fields. The applications have put forward a practical demand that the diamond substrates have an ultra-smooth surface and are free of structural damage. However, precision polishing of diamond is challenging due to the extreme hardness and chemical inertness. The focus of this study is to prepare nanoscale smooth polycrystalline diamond films with roughness Ra down to 0.1 nm using chemical and mechanical synergies. After processing, the surface roughness and quality of CVD diamond film were characterized, and a material removal mechanism was proposed. The graphitization process is accelerated when diamond contacts the transition metal Fe in the mechanical polishing process. In chemical mechanical polishing process, the polished surface of diamond C is transformed into deformed diamond C* under friction. A relatively soft polishing pad is used to increase the contact area with the diamond, which is transformed into a softer, easy-to-remove structure under the action of potassium permanganate oxidant, and then the reaction layer is removed again by mechanical friction.

Research on the Erosion Law and Protective Measures of L360N Steel for Surface Pipelines Used in Shale Gas Extraction.

The erosion of surface pipelines induced by proppant flowback during shale gas production is significant. The surface pipelines in a shale gas field in the Sichuan Basin experienced perforation failures after only five months of service. To investigate the erosion features of L360N, coatings, and ceramics and optimize the selection of two protective materials, a gas-solid two-phase flow jet erosion experimental device was used to explore the erosion resistance of L360N, coatings, and ceramics under different impact velocities (15 m/s, 20 m/s, and 30 m/s). An energy dispersive spectroscope, a scanning electron microscope, and a laser confocal microscope were employed to analyze erosion morphologies. With the increase in flow velocity, the erosion depth and erosion rate of L360N, coating, and ceramic increased and peaked under an impact velocity of 30 m/s. The maximum erosion rate and maximum erosion depth of L360N were, respectively, 0.0350 mg/g and 37.5365 µm. Its primary material removal mechanism was the plowing of solid particles, and microcracks were distributed on the material surface under high flow velocities. The maximum erosion rate and maximum erosion depth of the coating were, respectively, 0.0217 mg/g and 18.9964 µm. The detachment of matrix caused by plowing is the main material removal mechanism. The maximum erosion rate and maximum erosion depth of ceramics were, respectively, 0.0108 mg/g and 12.4856 µm. The erosion mechanisms were micro-cutting and plowing. Under different particle impact velocities, different erosion morphologies were observed, but the primary erosion mechanism was the same. The erosion resistance of the ceramics was higher than that of the coatings. Therefore, ceramic lining materials could be used to protect the easily eroded parts, such as pipeline bends and tees, and reduce the failure rate by more than 93%. The study provided the data and theoretical basis for the theoretical study on oil and gas pipeline erosion and pipeline material selection.

Analysis of micro-hole formation in titanium nanofilms using a low power CW laser

This study investigates the mechanisms and dynamics governing microhole formation in titanium nanofilms under the influence of a continuous-wave low-power laser emitting at 1070 nm. Two distinct configurations were explored: one in which the laser interacted with the titanium film in an air environment (referred to as configuration AM), and the other in which the laser beam passed through glass before reaching the titanium film (referred to as configuration SM). Our experiments demonstrated that microhole formation is possible in both configurations. However, the threshold powers, hole characteristics, and time scales involved differ significantly between AM and SM configurations. Temperature distribution simulations, based on a linear absorption model, revealed notable differences in peak temperatures between these two configurations, primarily attributed to variations in focal spot size and Fresnel losses. These temperature variations resulted in significantly different mechanisms of material removal in both configurations. In the AM configuration, the boiling temperature was not achieved, even at the highest power; however, a melting pool was formed at powers exceeding 50 mW. Thus, the primary driver of microhole formation was the Marangoni effect, which caused molten material to flow tangentially towards the edges of the molten pool. Furthermore, titanium oxidation was identified as a competing process contributing to changes in optical transparency and potentially inhibiting the complete formation of holes. Conversely, within the SM configuration, boiling temperatures are easily achieved, leading to localized boiling and the formation of gas bubbles near the glass–titanium interface. As a result, the rupture of the bubble through the capping molten layer led to a vigorous expulsion of both gas and material, allowing for the creation of microholes even at remarkably low laser power levels (10 mW). Notably, in this configuration, the influence of titanium oxidation is negligible due to the relatively short time scale involved (hundreds of microseconds).

Multi-criteria decision making for better quality indicators in µ-EDM using TiN-coated WC electrode

ABSTRACT It is highly essential to enhance the micro EDM process while machining titanium specimens. The utilization of coated electrode and adaptation of optimization algorithms in the process can enhance the material removal mechanism. In the present work, an attempt was made to find the influence of TiN coated tungsten carbide electrode in micro EDM process while machining titanium alloy specimens. It was also attempted to adopt DEAR-based optimization in the process. The TiN coating can produce lower TWR with better surface quality than uncoated tungsten carbide electrode. The capacitance has higher influential nature in µ-EDM since it controls the charging and discharging process during the spark formation across discharge gap. It was found that voltage (Level 3), capacitance (Level 3), and the tool rotation (Level 2) can create better quality measures under the prediction error of 2.3%. The optimal combination can enhance the machining accuracy with tiny craters formation.

Material Removal Mechanisms of Polycrystalline Silicon Carbide Ceramic Cut by a Diamond Wire Saw.

Polycrystalline silicon carbide (SiC) is a highly valuable material with crucial applications across various industries. Despite its benefits, processing this brittle material efficiently and with high quality presents significant challenges. A thorough understanding of the mechanisms involved in processing and removing SiC is essential for optimizing its production. In this study, we investigated the sawing characteristics and material removal mechanisms of polycrystalline silicon carbide (SiC) ceramic using a diamond wire saw. Experiments were conducted with high wire speeds of 30 m/s and a maximum feed rate of 2.0 mm/min. The coarseness value (Ra) increased slightly with the feed rate. Changes in the diamond wire during the grinding process and their effects on the grinding surface were analyzed using scanning electron microscopy (SEM), laser confocal microscopy, and focused ion beam (FIB)-transmission electron microscopy (TEM). The findings provide insights into the grinding mechanisms. The presence of ductile grinding zones and brittle fracture areas on the ground surface reveals that external forces induce dislocation and amorphization within the grain structure, which are key factors in material removal during grinding.

A cross-scale material removal prediction model for magnetorheological shear thickening polishing

Conventional polishing methods face significant challenges for achieving excellent performance on complex surfaces. The magnetorheological shear thickening polishing (MRSTP) method, with its dual-stimulus response of shear thickening and magnetization enhancement, offers an effective solution for polishing complex surfaces. However, existing models fail to elucidate the cross-scale material removal mechanisms in MRSTP owing to the coupling of magnetic and flow fields. In this study, a comprehensive model was proposed to address the the challenge of predicting the cross-scale material removal rate (MRR) in MRSTP for complex surfaces. Analytical and finite difference methods were employed to solve the pressure distribution during the MRSTP process using magnetohydrodynamics. By incorporating the pressure distribution, an MRR predictive model was developed for arbitrary points on the workpiece surface based on the indentation theory for active abrasive grains. The material removal mechanism was explored by considering elastic and plastic deformation under fluid pressure. The experimental validation showed a relative error of 14.9 % between the theoretical and experimental MRR. Experiments on aero-engine blade tenons demonstrated that the established MRR model is well suited for application to complex surfaces. This study ultimately reveals the material removal mechanism of MRSTP with coupled magnetic and flow field, providing a new foundation for predicting MRR on complex surfaces.

Rolling mechanism profundities on material removal mechanism of surface-textured GaN using Molecular dynamics simulation

Molecular dynamics simulation examines how the polishing tool's rotating velocity and axes affect surface nanotribological properties and material removal mechanism of patterned gallium nitride (GaN) substrates. Frictional coefficient and average contact area affect material removal rate (MRR) variance. Rotating speed increases the frictional coefficient and contact area, elevating MRR. Anticlockwise abrasives have substantially higher root-mean-square roughness (RMS) than clockwise ones. After polishing, increasing the rotating angle increases the frictional coefficient, average contact area, MRR, and RMS. MRR enhancement is maximum at −15 rad/ns, the only spinning velocity that improves MRR. RMS improvement ratio is highest when the polishing tool spins clockwise or the rotational axis orientation is lowered. Particularly, the MRR and RMS improvements after the polishing process can reach 103.8 % and 223.5 %, respectively. These findings help explain atomic-scale GaN-based material removal and deformation with frictional resistance and erosion by polishing.

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.