Material Removal Research Articles

The influence of the types of cluster composite abrasives on the performance of fixed abrasive pads in processing quartz glass

To enhance the material removal rate (MRR) and surface quality of quartz glass lapping, a new method is proposed utilizing a fixed cluster composite abrasive pad (FCCAP) for processing quartz glass. Firstly, cluster composite abrasives (CCA) with a particle size of 28 μm were prepared using the normal temperature and pressure sintering method, including cluster Al2O3-diamond composite abrasives (CADCA), cluster diamond-diamond composite abrasives (CDDCA), and cluster SiO2-diamond composite abrasives (CSDCA). Secondly, using CCA as the abrasive and relying on ultraviolet curing technology, three types of FCCAP were prepared: fixed cluster Al2O3-diamond composite abrasive pads (FCADCAP), fixed cluster diamond-diamond composite abrasive pads (FCDDCAP), and fixed cluster SiO2-diamond composite abrasive pads (FCSDCAP). Simultaneously, to validate the performance of the prepared FCCAPs, three types of fixed single crystal abrasive pads were prepared using the same process with single crystal Al2O3 (SCA), single crystal diamond (SCD), and single crystal SiO2 (SCS) with a particle size of 28 μm. Using quartz glass as the processing object, lapping experiments and friction and wear experiments were conducted, with MRR, surface roughness Ra, and coefficient of friction (COF) selected as evaluation indexes to compare and study the lapping performance of the six pads. FCCAP demonstrated higher machining efficiency, with FCDDCAP achieving the highest MRR of 3.611 μm/min. Additionally, after FCCAP lapping, the surface roughness Ra of quartz glass is lower, to some extent repairing surface damage such as large scratches. Among them, FCSDCAP achieved the lowest surface roughness of 91.564 nm. Finally, FCCAP exhibits superior friction and wear performance, with FCSDCAP samples having the highest average COF of 0.127. Under the same abrasive particle size conditions, FCCAP has better processing capabilities, enabling efficient lapping of quartz glass.

Laser-induced plasma micromachining on surfaces parallel to the incident laser in different solutions

Laser-induced plasma micromachining (LIPMM) is an advanced technology that utilizes the plasma generated from laser breakdown to remove material, thereby facilitating the fabrication of microstructures. This paper explores the use of LIPMM on 304 stainless steel surfaces parallel to the laser beam in different solutions, focusing on the impact of the liquid environment on the machining process. It presents a theoretical analysis of the material removal mechanisms unique to this orientation and experimentally investigates how water, a salt solution, and ethanol affect plasma shockwave characteristics. Notably, the plasma shockwave in the salt solution demonstrates the most significant peak pressure and energy, enhancing the micromachining efficiency. These findings suggest that varying the liquid environment can significantly influence LIPMM's effectiveness, offering potential improvements in precision and control. This study broadens the understanding of LIPMM applications, especially in orientations not commonly explored, and opens new possibilities for advanced micromachining techniques in various industrial applications.

Direct laser patterning of ruthenium below the optical diffraction limit

We describe a method that can be used to produce ruthenium/ruthenium oxide patterns starting from a ruthenium thin film. The method is based on highly localized oxidation of a small surface area of a ruthenium film by means of exposure to a pulsed laser under ambient conditions. Laser exposure is followed by dissolution of the un-exposed ruthenium in a NaClO solution, which leaves the conductive, partially oxidized ruthenium area on the substrate. Spatially selective oxidation, material removal, and, by implication, patterning, are, therefore, achieved without the need for a photoresist layer. Varying the exposure laser parameters, such as fluence, focus diameter, and repetition rate, allows us to optimize the process. In particular, it enables us to obtain circular Ru/RuO2 islands with a sub-diffraction-limited diameter of about 500 nm, for laser exposure times as short as 50 ms. The capability to obtain such small islands suggests that heat-diffusion is not a limiting factor to pattern Ru by laser heating on a (sub-)micron scale. In fact, heat diffusion helps in that it limits the area where a sufficiently high temperature is reached and maintained for a sufficiently long time for oxidation to occur. Our method provides an easy way to produce metallic Ru/RuO2 (sub-)micron structures and has possible applications in semiconductor manufacturing.

Precise surface machining of fused silica using high stability atmospheric pressure microwave plasma jet with a new internal electrode

Plasma is a promising approach for machining of fused glass substrates. Developing high-performance microwave torch is the core element to ensure the processing accuracy of this technology. In this study, a spline curve-based microwave torch internal electrode structure was proposed, which increased the internal electric field strength by 54 %. The discharge dynamics simulation based on this electrode shows that the plasma is excited at the inner electrode tip and the bottom of the resonant cavity, then it expands to form a linear discharge region and eventually fill the discharge tube. It was revealed by CCD images that with the increase of carrier gas flow rate, turbulent flow state appears in the tail of the jet. OES data shows that microwave Ar plasma can effectively dissociate CF4, and due to the oxidation effect of oxygen, CFx and C2 content decrease significantly with the addition of oxygen. The machining experiment on fused silica shows that the material removal stability of this torch reaches 3.69 %, and the removal rate increases nYarly with dwell time due to thermal effect. Finally, the machining performance of the atmospheric pressure microwave plasma jet was verified by figuring of a planar fused silica surface reducing the form error from 108.1 nm RMS to 16.5 nm RMS.

Abrasive waterjet machining of titanium alloy using an integrated approach of taguchi-based passing vehicle search algorithm

AbstractThe titanium alloy, Ti6Al4V, is a popularly used material in aerospace and medical applications due to its specific attributes, such as excellent strength-to-weight ratio and resistance to corrosion. Ti6Al4V is challenging to machine using conventional methods due to its poor thermal conductivity, which necessitates the use of unconventional machining methods like abrasive water jet machining (AWJM). In this work, AWJM was preferred for machining Ti6Al4V, considering three key process variables: nozzle traverse speed (Tv), abrasive flow rate (Af), and stand-off distance (Sd). The performance of the AWJM process was assessed using three main metrics: Material removal rate (MRR), Surface roughness (SR), and Kerf taper angle (θ), which were crucial for evaluating the effectiveness of the AWJM. Taguchi’s L9 array, a design of experiments method, was used to plan the experiments. The adequacy of the developed models was assessed by analysis of variance (ANOVA). ANOVA results have shown that Tv, Af, and Sd were found to have a significant effect on MRR, SR, θ with contributions of 73.15%, 49.72%, and 78.35% respectively. The Passing Vehicle Search algorithm was adopted to find the global optimal solution. Simultaneous optimization results using the PVS algorithm have shown the optimal MRR, SR, and θ values of 0.17 g/min, 3.28 μm, and 2.45, respectively, at Tv of 237 mm/min, Af of 450 g/min, and Sd of 2.0 mm. The optimization results with Pareto points will help to achieve desired outcomes by selecting appropriate input conditions.

Optimization of Process Parameters of Wire Electric Discharge Machining Process for Machining AISI A2 Tool Steel

Optimization of Process Parameters of Wire Electric Discharge Machining Process for Machining AISI A2 Tool Steel

Tribo-electrochemical investigation of 60NiTi alloy in saline solution

This research explores the tribocorrosion behaviour of 60NiTi alloy, also known as NiTiNOL60, when exposed to a saline environment. Our investigation focuses on understanding the relationship between corrosion and wear rates and assessing surface damage and material degradation. To conduct our experiments, we employed a linear reciprocating ball-on-plate tribometer coupled with electrochemical polarisation using a three-electrode cell configuration to assess the combined effects of corrosion and sliding wear. Surface characterisation was carried out through scanning electron microscopy and energy dispersion spectroscopy, revealing the material to be a Ni-rich 60NiTi alloy, with surface oxidation evident in the electrolyte medium. Our electrochemical findings indicate the occurrence of localised corrosion in both cathodic and anodic regimes, with corrosion pit nucleation, cavities, and cracks being accelerated by reciprocating sliding and corrosion potential. These interactions exposed the material surface to various wear mechanisms, including abrasive, adhesive, oxidative, corrosive, and fatigue processes. This study underscores the significant influence of mechanical properties on the rate of material degradation due to corrosion, while also highlighting the substantial impact of prevailing electrochemical conditions on the rate of mechanical material removal. This paper offers valuable insights for designers working on load-bearing structures in saline environments.

Mechanism and deformation behavior of elliptical vibration-assisted cutting of FeNiCrCoAl high entropy alloy

The mechanical response of FeNiCrCoAl high entropy alloy (HEA) under conventional cutting and ultrasonic elliptical vibration-assisted cutting (UEVAC) was investigated using molecular dynamics (MD) methods. The effects of vibration period, axial amplitude, and normal amplitude on the material removal mechanism were studied. The results show that the average cutting temperature of the workpiece under UEVAC is significantly higher than that under conventional cutting. The high-temperature distribution area under UEVAC presents an intermittent distribution pattern, which not only facilitates the cutting process but also plays a positive role in the protection of the tool. Furthermore, as the vibration period shortens, both the average principal stress experienced by the workpiece and the triaxial cutting force decrease, while the height and quantity of chip atoms significantly increase. When the vibration period is shortened to 5 ns, the number of chip atoms is about twice that of conventional cutting, which is equivalent to doubling the removal efficiency of the material. Although an increase in axial amplitude causes an increase in the average temperature of the workpiece, it also results in larger negative principal stress. When the axial amplitude A increases to 20 Å, the peak value of the negative principal stress generated inside the base material exceeds 8000 GPa, and the triaxial cutting force tends to increase, without a significant increase in the number of chip atoms. With the increase in normal amplitude B, the average cutting temperature of the matrix also increases. But there is no significant change in the direction and magnitude of the principal stress, and the triaxial cutting force continuously increases. This study provides a theoretical basis for achieving high surface quality of HEAs.

Wear behaviour of abrasive tools and its effect on surface integrity during polishing superalloy GH4169G with abrasive cloth flap wheels

In polishing nickel-based superalloys, the surface quality and dimensional accuracy of the workpiece are closely related to the wear of the abrasive tools. Over the years, several researchers have studied the wear of grinding wheels or abrasive belts, including the effects of various machining methods, abrasive materials, and machining parameters on the wear of abrasive tools. However, there is not enough research on the wear mechanism of the abrasive cloth flap wheel (ACFW). In this paper, during polishing GH4169G with ACFW, the wear evolution mechanism of ACFW and its effect on the surface integrity of GH4169G were investigated. First, the variations in material removal and ACFW wear amounts during the polishing process were analysed, and the different wear stages were divided based on the polishing ratio. Second, the mic-morphology and surface element distribution of ACFW at different wear stages were investigated using SEM and, EDS, and the wear evolution mechanism of ACFW was analysed. Finally, the effects of ACFW wear on the surface morphology, surface oxidation and microstructure of GH4169G were investigated by SEM, EDS, XRD, and EBSD. The results showed that the primary wear forms of ACFW were stepped fracture, cleavage fracture, blunt, pull-out, and adhesion wear. During the initial wear stage, the proportion of each wear form was relatively balanced. In the medium wear stage, fracture wear was the main wear form. Blunt and adhesive wear were the primary forms of wear during the final wear stage. In addition, with ACFW wear, the surface roughness tend to decrease first and then increase, however, the refinement level of the grains, the intensity of plastic deformation and the intensity of the oxidation reaction gradually increased. This study provides effective guidance for developing more wear-resistant abrasive tools and optimising the grinding and polishing processes.

Wheatstone bridge sensor arrays in foil by robust μ-via technology combining femtosecond-laser drilling and pulsed electrodeposition

Flexible sensor arrays with multilevel circuits typically require complex production cycles leading to high costs and reliability issues. For establishing flexible arrays of strain sensors in Wheatstone bridge configurations structures on different levels within flexible films have to be connected by robust μ-via technology. Usually, dry etching is used to establish via-holes and direct current (DC) electrodeposition is used to fill them with copper. However, dry etching can lead to damages in the underlying electrode or incomplete removal of polymeric material, as inhomogeneities of polymeric foil thicknesses cannot completely be eliminated. This affects the quality of the plating and the reliability of the μ-via connections. It is aggravated by the fact that DC electroplated copper is often weakened by various defects, such as small voids. This article describes a reliable and less complex fabrication process for a Wheatstone bridge sandwich structure consisting of five polymer interlayers separating four metal layers. The femtosecond-laser μ-via drilling proved to be fast, material selective and therefore tolerant to inhomogeneities of polymeric foil thicknesses. Moreover, pulsed current (PC) electrodeposition significantly improved the quality of the copper filling. No voids were found using electron microscopy. Finally, the respiration monitoring sensors produced using this method were subjected to repetitive cycles of bending and relaxation. At a frequency of five cycles per second, reproducible cycles of signal changes were obtained, indicating the usefulness for detecting respiratory cycles of premature infants.

Investigations on material removal mechanism during laser-assisted grinding silicon nitride ceramics

Investigations on material removal mechanism during laser-assisted grinding silicon nitride ceramics

In-situ reconditioning mechanism for fixed abrasive pads based on the wear behavior of loose grains

C-plane sapphire (α-Al2O3) is a commonly used substrate material for integrated circuits and Light-emitting diodes (LEDs). Efficient, stable, and low-damage lapping processes are used to ensure surface smoothness and meet application requirements. Fixed abrasive pads (FAPs) are typically used for the lapping of sapphire substrates, but the pads are prone to be glazed or even failed. In this study, loose alumina grains were used for in-situ reconditioning of fixed diamond abrasive pads. The material removal rate and surface roughness of the lapped sapphire substrate were calculated, the types and size distributions of the wear debris were analyzed, the surface morphology of the FAP after lapping was examined, and an online monitoring system was used to track the friction coefficient between the FAP and the sapphire substrate. In order to determine the ideal size and concentration of loose grains and to reveal the in-situ reconditioning mechanisms for the fixed diamond abrasive pads, the effects of the size and concentration of loose alumina grains in the lapping slurry on the in-situ reconditioning of the FAP were investigated. This was done by examining the wear behavior of loose alumina grains during the lapping processes of sapphire substrates.

How does the uncut chip thickness affect the deformation states within the primary shear zone during metal cutting?

The deformation states within the primary shear zone (PSZ) significantly affect material removal during machining. Uncut chip thickness (UCT) is an important factor that influences the material deformation states. However, the specific mechanism by which UCT influences the deformation states within PSZ remains unknown. This study aims to investigate the relationship between the deformation states in PSZ and UCTs via in-situ measurement and microscopic characterization techniques. Using the digital image correlation (DIC) technique, strain and strain rate distributions were derived to reveal the discrepant deformation in PSZ with increasing UCT. Furthermore, velocity vector fields and Electron Back-Scattered Diffraction (EBSD) characterizations were employed to examine the heterogeneity of deformation modes. To determine the specific deformation information, a deformation extraction framework based on the deformation gradient tensor theory was developed. Thus, strong and weak shear modes within PSZ were revealed based on the full-field deformation information of compression and extension. As the UCT increased, the transition of deformation states from a strong shear state to a hybrid shear state was determined. This work presents a new understanding of the deformation mechanism within PSZ in a ductile material of pure iron. A critical UCT was proposed to guide the cutting process to avoid inefficient weak shear mode.

Material removal model of magnetoelastic abrasive particles in dual-disk magnetic cutting edge preparation

Material removal model of magnetoelastic abrasive particles in dual-disk magnetic cutting edge preparation

Ultrafast processing of zirconia ceramics by transient and selective laser absorption

Ultrashort-pulse lasers (USPLs) are used in the machining of zirconia ceramics (ZrO2) because of their extremely high peak intensities. However, highly efficient and high precision microprocessing of ZrO2 remains challenging. In this study, we applied a transient and selective laser (TSL) processing technique by combining a USPL and a continuous-wave (CW) laser to realize ultrafast drilling of opaque ZrO2. Ultra-high-efficiency TSL drilling of ZrO2 was achieved with a processing efficiency 1800 times higher than that of USPL drilling. The material removal mechanism, hole formation process, and parameter dependence of TSL drilling were revealed by direct observation of the internal processing phenomenon on a timescale of microseconds. The variations in the processed surface characteristics, including surface morphology, elemental composition, and phase composition, are also presented. Subsequently, the effect of different excited electron regions occurring in the picosecond timescale induced by the USPL on the TSL drilling performance is discussed. Finally, the repeatability and stability of the TSL processing were verified by fabricating microarrays of different sizes. This study will contribute to revealing the ultrafast processing mechanisms of TSL processing in ZrO2 microfabrication. Furthermore, this technique can significantly broaden the applications of ZrO2 in the advanced electronic industry by greatly improving the microprocessing efficiency.

Application of Taguchi Method, ANOVA Analysis, and TOPSIS Technique in Optimization of Process Parameters for Surface Roughness and Material Removal Rate in Electrochemical Machining of Al-SiC MMCs

Application of Taguchi Method, ANOVA Analysis, and TOPSIS Technique in Optimization of Process Parameters for Surface Roughness and Material Removal Rate in Electrochemical Machining of Al-SiC MMCs

Three-Dimensional Printed Teeth in Endodontics: A New Protocol for Microcomputed Tomography Studies.

This study aimed to describe a support material removal protocol (SMRP) from inside the root canals of three-dimensional printed teeth (3DPT) obtained by the microcomputed tomography (microCT) of a natural tooth (NT), evaluate its effectiveness by comparing the 3DPT to NT in terms of internal anatomy and behaviour toward endodontic preparation, and evaluate if 3DPT are adequate to assess the differences between two preparation systems. After the SMRP, twenty 3DPT printed by PolyJet™ were microCT scanned before preparation and thereafter randomly assigned into two groups (n = 10). One group and NT were prepared using ProTaper Gold® (PTG), and the other group with Endogal® (ENDG). MicroCT scans were carried out after preparation, and the volume increase, volume of dentin removed, centroids, transportation, and unprepared areas were compared. For the parameters evaluated, no significant differences were found between the 3DPT and NT before and after preparation (p > 0.05), and no significant differences were found between the 3DPT PTG group and the 3DPT ENDG group (p > 0.05). It can be concluded that the SMRP described is effective in removing the support material SUP706B™. PolyJet™ is adequate for printing 3DPT. Furthermore, 3DPT printed with high-temperature RGD525™ have similar behaviour during endodontic preparation with PTG as the NT, and 3DPT can be used to compare two preparation systems.

Experimental Study of Electrical-Assisted Nanomachining of Monocrystalline Copper Using Customized Tungsten Tip

As a promising micro/nanofabrication method, electrical-assisted nanomachining has obtained substantial attention due to its high material removal rate and attainable superior surface quality. In this study, a rectangular wave electrical signal was applied for nanomachining by a customized tungsten tip. Owing to the coupling effect between the electric field and mechanical force, the cutting depth of the machined grooves can be expanded. In electrical-assisted groove processing, a depth of 270 nm and an aspect ratio of 0.6 on the copper sample can be achieved. The influence of operation parameters including applied voltage, frequency, duty ratio, normal force and cutting speed on the machining performance was investigated in terms of the groove depth, width, aspect ratio, and surface roughness. The potential machining mechanisms should be a combination of electric field force, nanoscale electric discharge, electric contact thermal effects, possible annealing behavior, and scraping and plowing actions induced by mechanical forces.

Development of conductive SiC-ZrN-TiB2 ceramics: A pathway towards electrical discharge machinable SiC based ceramics

Dense silicon carbide (SiC) composites with 0–30 vol% (ZrN-TiB2) were fabricated by using liquid phase spark plasma sintering at a relatively lower sintering temperature (1800 °C) and shorter holding time (5 min). The effects of co-addition of ZrN and TiB2 on densification, mechanical properties, and electrical conductivity of SiC ceramics were investigated. The reinforcement significantly enhanced density of sintered composites, while the phase analysis and microstructure confirm the suppression of β→α phase transformation in the SiC matrix. The fracture toughness ranged from 4.1 to 4.6 MPa·m0.5, hardness from 19.5 to 20.3 GPa, and electrical conductivity from 4.85 ×101 to 1.25 ×103 (Ω·cm)−1. Incorporating conductive reinforcements and nitrogen additives enhanced electrical conductivity. Successful wire-EDM cutting of SiC-ZrN-TiB2 composites demonstrate the feasible alternative to conventional machining of non-oxide ceramics with a maximum material removal rate of 8.54 mm2/min.

The sequential microbial breakdown of pectin is the principal incident during water retting of jute (Corchorus spp.) bast fibres

The extraction of bast fibres such as jute from plant stems involves the removal of pectin, hemicellulose, and other noncellulosic materials through a complex microbial community. A consortium of pectinolytic bacterial strains has been developed and commercialized to reduce the retting time and enhance fibre quality. However, there are currently no studies on jute that describe the structural changes and sequential microbial colonization and pectin loss that occur during microbe-assisted water retting. This study investigated the stages of microbial colonization, microbial interactions, and sequential degradation of pectic substances from jute bark under controlled and conventional water retting. The primary occurrence during water retting of bast fibres is the bacterially induced sequential breakdown of pectin surrounding the fibre bundles. The study also revealed that the pectin content of the jute stem significantly decreases during the retting process. These findings provide a strong foundation for improving microbial strains for improved pectinolysis with immense industrial significance, leading to a sustainable jute-based “green” economy.