Material Removal Rate Research Articles

Innovative synthesis of CeO2 nanoparticles for advanced chemical mechanical polishing

This study presents a novel chemical precipitation method for synthesizing cerium dioxide (CeO₂) nanoparticles with superior chemical mechanical polishing (CMP) performance. Cerium nitrate and ammonia were used as the cerium source and precipitant, respectively, in a nitrogen atmosphere. The hypothesis that higher oxygen vacancy density and redox capability would enhance the material removal rate (MRR) was tested. The synthesized CeO₂ nanoparticles exhibited improved crystallinity and oxygen exchange properties, as confirmed by XPS and H₂-TPR analysis. The results showed that CeO₂ synthesized at 0.7 M cerium nitrate after 24 hours outperformed commercial CeO₂ with an MRR of 3095.53 Å/min, attributed to the high concentration of Ce³⁺ ions and oxygen vacancies. This study provides new insights into the role of oxygen exchange and vacancy density in optimizing CeO₂-based abrasives for CMP applications.

Abrasive aqua jet machining of NiTiV ternary smart alloy

ABSTRACT Nickel–titanium shape memory alloys (SMAs) are popular due to their usefulness and functional characteristics. The binary NiTi SMA was alloyed with vanadium to improve memory retention properties. In this study, the abrasive aqua jet machining method was adopted to machine the Ni50Ti48V2 ternary SMA to minimize the kerf taper angle (KTA), surface roughness (Ra) of machined Ni50Ti48V2 surface, and enhance the material removal rate (MRR). RSM-BBD optimization using the input variables such as abrasive flow rate (AFR), water jet pressure (PWJ), nozzle traverse speed (VTS), and standoff distance (SFD) predicted that PWJ and SFD highly contributed to MRR, Ra, and KTA responses. Small variation in variation after optimized AWJM conditions, and XRD analysis confirmed no phase changes after AWJM.

Process optimization and finite element modeling in magnetorheological abrasive finishing of SS-316L with surface characterization

This study explores the potential of Magnetorheological Abrasive Finishing (MRAF) for ultra-precision finishing of SS-316L using a high-performance Nd-Fe-B (N-35 grade) magnetic tool. Key parameters, including the relationship between normal force (Fn) and working gap, magnetic flux distribution, and finishing spot area, were analyzed using ANSYS 2020 R1® Magnetostatic module simulations. Material removal rate (MRR) and surface roughness (Ra) were optimized through response surface methodology (RSM) using a central composite design (CCD) with two primary input factors: SiC abrasive volume fraction (5%, 10%, 15%) and abrasive mesh size (800, 1000, 1200). Statistical analysis via ANOVA revealed a significant influence of process variables, achieving a remarkable surface finish with a minimum Ra of 52 nm in just 60 min, utilizing an MR fluid with 10% SiC abrasives. Microscopic and spectroscopic evaluations confirmed enhanced surface morphology and microstructural refinement. Moreover, bioactivity studies in simulated body fluid highlighted improved hydroxyapatite layer formation on the finished SS-316L samples, underscoring the process’s potential for biomedical applications.

Role of dry media in influencing performance during processing by centrifugal superfinishing

ABSTRACT To achieve better surface quality and higher efficient finishing of AISI 52,100 steel cylindrical roller surfaces, a novel dry medium was prepared, which is composed of millimeter-sized adsorptive medium matrix and polishing paste containing micron-sized abrasives. The study utilized centrifugal superfinishing to examine the effects of dry media with various abrasive types, sizes, and polishing paste ratios. The influence of these dry media on the processing performance was comprehensively evaluated, covering parameters including material removal rate, roughness decrease rate constant (K r ), roughness limit (Ra lim ) value, surface morphology, and profile. In addition, the processing mechanism was revealed. This study provides valuable insights into the development and performance regulation of new media for nano-level superfinishing of complex surfaces.

Investigation of Electrochemical Discharge Machining for Tungsten Carbide: Effects of Electrolyte Composition on Material Removal Rate and Surface Quality

Abstract Tungsten carbide (WC-Co) with a cobalt binder has been widely used in industrial application. Through their high wear resistance and hardness, which make it a challenge to machine. Electrochemical discharge machining (ECDM) is a newly developed hybrid technique used to machine conductive and nonconductive materials. Tungsten carbide machining is an area that needs more investigation. In this study, different types of electrolytes have been tested in the electrochemical machining of tungsten carbide. It has been concluded that tungsten carbide was successfully machined with electrolytes that were either neutral salts or a combination of neutral salts and hydroxides, the highest material removal rate achieved was (0.09250 g/min), and the average surface roughness achieved in this work was measured at (Ra 0.9275 µm). However, deposition took place on the surface of machined tungsten carbide when the samples were treated with sodium hydroxide and potassium hydroxide. EDX analysis of successfully machined tungsten carbide samples reveal the presence of carbon (C) due to diffusion from the base material and oxygen (O), most likely due to oxidation brought on by the high temperatures utilized. Scanning electron microscopy confirmed that the machined surfaces had craters, pores, restricted microcracks, and re-deposited melt particles, among other things.

Multiscale model of material removal for ultrasonic assisted polishing of cylindrical surfaces

Ultrasonic assisted polishing is an effective and precise method in engineering production that applies in finishing surface. A multiscale model was developed which is able to forecast the surface micromorphology and material removal rate. Process factors were considered include polishing force, grain diameter, ultrasonic amplitude and so on in this model at different scales. The impact of various process factors on surface roughness and material removal rate were analyzed by orthogonal experimental table. The perfect combination of process parameters was identified, and its effectiveness was verified through both simulations and experimental analysis, with an error rate below 9.43 %. To provide a mechanism study of ultrasonic polishing of curved surfaces and optimization of process parameters by this theoretical model.

Towards atomic-scale smooth surface manufacturing of β-Ga2O3 via highly efficient atmospheric plasma etching

Abstract The highly efficient manufacturing of atomic-scale smooth β-Ga2O3 surface is fairly challenging because β-Ga2O3 is a typical difficult-to-machine material. In this study, a novel plasma dry etching method named plasma-based atom-selective etching (PASE) is proposed to achieve the highly efficient, atomic-scale, and damage-free polishing of β-Ga2O3. The plasma is excited through the inductive coupling principle and carbon tetrafluoride is utilized as the main reaction gas to etch β-Ga2O3. The core of PASE polishing of β-Ga2O3 is the remarkable lateral etching effect, which is ensured by both the intrinsic property of the surface and the extrinsic temperature condition. As revealed by density functional theory-based calculations, the intrinsic difference in the etching energy barrier of atoms at the step edge (2.36 eV) and in the terrace plane (4.37 eV) determines their difference in the etching rate, and their etching rate difference can be greatly enlarged by increasing the extrinsic temperature. The polishing of β-Ga2O3 based on the lateral etching effect is further verified in the etching experiments. The Sa roughness of β-Ga2O3 (001) substrate is decreased from 14.8 to 0.057 nm within 120 s, and the corresponding material removal rate reaches up to 20.96 μm/min. The polished β-Ga2O3 displays significantly improved crystalline quality and photoluminescence intensity, and the polishing effect of PASE is independent of the crystal faces of β-Ga2O3. In addition, the competition between chemical etching and physical reconstruction, which is determined by temperature and greatly affects the surface state of β-Ga2O3, is deeply studied for the first time. These findings not only demonstrate the high-efficiency and high-quality polishing of β-Ga2O3 via atmospheric plasma etching but also hold significant implications for guiding future plasma-based surface manufacturing of β-Ga2O3.

Prediction of the material removal rate in bonnet polishing using a Bayesian optimization deep neural network

The material removal mechanism in robotic bonnet polishing is complex and influenced by multiple factors, necessitating an appropriate method to establish a material removal model. This study employs a Bayesian optimized deep neural network (BO-DNN) to model the intricate relationship between polishing parameters and material removal rate (MRR) using removal function spot experimental data. The tree-structured Parzen estimator (TPE) improves model convergence speed and accuracy, while particle swarm optimization (PSO) assists in inverse verification. Results show that the BO-DNN model achieves a root mean square error (RMSE) of 0.0293 and a Pearson correlation coefficient (PCC) of 99.42% for the total sample, representing approximately a 50% improvement in predictive accuracy over the unoptimized DNN model. The inverse verification results closely match the experimental data, confirming the model’s reliability. This study offers theoretical insights and practical references for advancing robotic bonnet polishing technology.

Optimisation of chemically assisted mechanical polishing process parameters for polycrystalline diamond based on photo-Fenton reaction

Polycrystalline diamond (PCD) has ultra-high thermal conductivity and is suitable for use as a thermal substrate material for semiconductor power devices. However, the high hardness, good wear resistance and chemical inertness of PCD lead to low machining efficiency and poor machined surface quality. Chemically assisted mechanical polishing based on the photo-Fenton reaction enables efficient PCD processing and high surface quality. In this study, Box-Behnken response surface experiments were employed to investigate the influence of the photo-Fenton reaction polishing process parameters (H₂O₂ concentration, light intensity, polishing pressure and abrasive concentration) and their interactions on the polishing process. Regression equations were constructed to model the material removal rate (MRR) and surface roughness (Ra) and to optimise the process parameters. Finally, the polishing mechanism was analysed. The results demonstrated that the effects of polishing pressure, polishing pressure-abrasive concentration, abrasive concentration and H2O2 concentration on the material removal rate were statistically significant. Furthermore, the effects of polishing pressure, H2O2 concentration, abrasive concentration, polishing pressure-abrasive concentration, H2O2 concentration-light intensity and light intensity on the surface roughness were also found to be statistically significant. The optimal process parameters were identified as a light intensity of 150 mW/cm2, a H₂O₂ concentration of 15 wt%, a polishing pressure of 0.89 MPa, and an abrasive concentration of 5 wt%. These parameters yielded a material removal rate of up to 666.9 nm/h and a surface roughness of Ra 2.58 nm. The polishing mechanism of the photo-Fenton reaction on PCD can be described as follows: the photo-Fenton reaction produces •OH, which then oxidises the PCD surface to generate an oxide layer. This layer is subsequently removed by the mechanical action of the abrasive, and the oxidation and mechanical removal continue to occur on the exposed new PCD surface. It has been demonstrated that, under the condition of balance between the mechanical action and the chemical action, a better quality of the surface can be obtained. This paper offers further evidence in support of the use of the photo-Fenton reaction in the context of PCD polishing.

Experimental investigation on optimizing wire-cut EDM process parameters of hybrid MMC(AA7475/ZrO2/Gr) using artificial neural network

Abstract Wire cut Electrical discharge machining (WCEDM) is a widely used method for machining complex shapes in advanced materials like metal matrix composites (MMCs) and hybrid metal matrix composites (HMMCs). To address these challenges, this study focusses on the wire-cut EDM (WCEDM) process of a workpiece made from zirconium dioxide and graphite-reinforced aluminium alloy 7475 with a molybdenum electrode. The effects of input process variables such as peak current (IP), pulse-on-time (TON), and flushing pressure (PF) on the output response features are investigated. These output responses include material removal rate (MRR), surface roughness (SR), and wire wear ratio (WWR). To optimise the process parameters, the Taguchi design technique is used. An artificial neural network (ANN) with a feed-forward back propagation architecture is utilised to find the best fit for the optimisation challenges. ANN predicted the results with an accuracy of 97.81% for MRR, 97.95% for SR and 95.865% for WWR. The results reveal that the WCEDM of AA7475/ZrO2/Gr with a molybdenum electrode achieved minimal WWR and SR, while maximizing the MRR.

Experimental study of chemical mechanical polishing of polycrystalline diamond based on photo-Fenton reaction

Polycrystalline diamond (PCD) is widely used in cutting tools, optical devices, and heat dissipation tools due to its exceptional hardness, wear resistance, and thermal conductivity. However, these excellent properties also make polishing the PCD surface a challenge. Traditional polishing methods struggle to achieve both high material removal efficiency and high-quality surface finishes simultaneously. This paper proposes a chemical mechanical polishing (CMP) method for PCD based on the photo-Fenton reaction. The method utilizes the reaction between H₂O₂ and Fe₃O₄ under ultraviolet (UV) light to generate highly oxidative hydroxyl radicals (·OH), effectively oxidizing the PCD surface to reduce the difficulty of processing. The concentration of ·OH and Fe2⁺/Fe³⁺ in different reaction solutions was measured using spectrophotometry. Results indicate that the concentration of ·OH is highest in the photo-Fenton solution, and UV light promotes the conversion of Fe³⁺ to Fe2⁺, sustaining the ongoing photo-Fenton reaction. Through single-factor polishing experiments, the effects of various processing parameters on the CMP performance of PCD were investigated. The results show that the material removal rate of PCD increases with increasing concentrations of H₂O₂, abrasive particle size, polishing pressure, and polishing disc speed. In contrast, the removal rate first increases and then decreases with increasing UV light intensity and Fe₃O₄ concentration. Additionally, the surface roughness (Ra) of PCD decreases initially and then increases with increasing UV light intensity, abrasive particle size, polishing pressure, and polishing disc speed, while it decreases with increasing Fe₃O₄ and H₂O₂ concentrations. Under the conditions of 100 mW/cm2 UV light intensity, 2 wt% Fe₃O₄, 10 wt% H₂O₂, 5 wt% abrasive concentration, 0.5 μm abrasive particle size, 0.89 MPa polishing pressure, and a polishing disc speed of 60 r/min, the material removal rate of PCD reaches 698.7 nm/h, and the surface roughness Ra is 3.78 nm. The photo-Fenton reaction-based CMP method proposed in this paper provides a new approach to polishing hard-to-process materials.

An industrial robot-based sawing method for natural stone sculpture

Abstract In order to enhance the efficiency of stone sculpture machining while reducing natural stone waste and environmental pollution, a method for the efficient and green sawing of natural stone sculptures using industrial robots is proposed. The model contour is used as the directrix of the ruled surface to construct a ruled surface model that minimizes volume. The contour curve corresponding to this minimized-volume ruled surface model serves as the machining path for an integrated robotic diamond wire cutting system. A ruled surface model of Stanford Bunny was obtained by sawing a marble block using the robotic diamond wire cutting system. The experimental results show that the material removal rate of the robotic diamond wire cutting is 1.37 times that of saw blade cutting and 2.30 times that of grinding. The volume of stone powder generated during the processing was 0.16×10⁷mm³, accounting for only 1.47% of the total stone powder produced during the grinding process. In summary, the proposed method not only enhances processing efficiency but also reduces natural stone waste and mitigates environmental pollution.

Understanding the adsorption mechanism of benzotriazole and its derivatives as effective corrosion inhibitors for cobalt in chemical mechanical polishing

Cobalt is emerging as the next-generation interconnect material to replace copper for integrated circuit sub-10 nm technology nodes. Due to its susceptibility to corrosion, identifying effective corrosion inhibitors for Co during the chemical mechanical polishing (CMP) is crucial. In this study, theoretical computations and experimental approaches were employed to investigate the corrosion inhibition effects of benzotriazole (BTA) and its derivatives—methylbenzotriazole (TTA) and 5-carboxybenzotriazole—on Co surfaces. Quantum chemical calculations and molecular dynamics simulations were used to reveal the corrosion mechanism at the atomic level. The computational findings were further validated by electrochemical experiments. Among the inhibitors studied, TTA exhibited the highest adsorption affinity for the Co surface, achieving an inhibition efficiency of up to 91.71 %. This is attributed to the formation of a dense protective layer on the Co surface through both physical adsorption via intermolecular forces and chemical adsorption via charge transfer. CMP experiments demonstrated that all three inhibitors significantly reduce the material removal rate (MRR) of Co. Notably, when the TTA concentration reaches 9 mM, the MRR is reduced to 132.64 nm/min, meeting the requirements for Co bulk polishing. These findings suggest that TTA is a highly promising Co corrosion inhibitor for slurry development in CMP processes.

Chemical magnetic field-assisted batch polishing method of 316L stainless steel

316L stainless steel has been extensively employed in the manufacturing of medical equipment and biomedical implants because of its good ductility, corrosion resistance and biocompatibility, etc. However, there has always been a non-neglected problem of low polishing precision and efficiency in the whole machining chain for such parts, hence, it is difficult to meet the batch demand of the market for 316L stainless steel with high-precision surface. Based on the principle of magnetic field-assisted batch polishing (MABP) proposed by our research team previously, a novel chemical magnetic field-assisted batch polishing (CMABP) method here is developed by adding chemical reagents (i.e., the mixture of oxalic acid and hydrogen peroxide) in the preparation process of regular magnetic brush, desiring and expecting to further realize the polishing of 316L stainless steel with higher precision and efficiency simultaneously. The preliminary experimental results demonstrated that the value of surface roughness Sa after CMABP became smaller and the material removal rate increased comparing to that after MABP, which did verify the potential advantage of the established CMABP approach. In detail, CMABP experiments with pH value and H2O2 concentration as variables were carried out quantitatively. The results suggested that, within the set range of pH value (from 2 to 7) and H2O2 concentration (from 0.3 wt.% to 2.0 wt.%), when pH was chosen as 4 and H2O2 concentration was adjusted as 2.0 wt.%, the value of Sa after CMABP was the minimum, which could be 38% lower than that of MABP approximately. Nonetheless, material removal rate reached to the maximum, which could be around 168% more than that after MABP, when pH and H2O2 concentration were determined as 3.0 and 2.0 wt.%, respectively. Additionally, the discrepancy between the chemical and the regular magnetic brushes were detected and analyzed comparatively both at macro and micro scales. Also, the products on the surface of 316L stainless steel, such as the weak-binding layer and the passive layer, were discovered and taken to interpret the experimental phenomena of the surface roughness and material removal rate varying with the content of chemical reagents in CMABP, thereby revealing the material removal mechanisms correspondingly and interestingly. This work is capable of providing valuable reference undoubtedly for batch precision polishing of 316L stainless steel and other significant functional materials.

Hole drilling in basalt-reinforced sustainable composites using abrasive waterjet for construction applications

This study aimed to develop, characterize, and optimize abrasive waterjet (AWJ) machining of sustainable basalt fiber-reinforced polymer composites for construction and industrial applications. Dynamic mechanical analysis, thermogravimetric analysis, and X-ray diffraction revealed enhanced thermal stability, increased decomposition temperatures, and improved crystallinity, correlating with improved tensile strength of developed composites. To address drilling-induced damage that can compromise long-term quality and applicability, AWJ drilling parameters were optimized to minimize damage while enhancing material removal rates. A novel quantification method for entry total surface damage (ETD) was implemented to assess machining defects. Results showed that standoff distance significantly influences ETD and exit delamination, while higher water pressure reduces entry damage. Abrasive flow rate primarily affected the material removal rate. FE-SEM analysis revealed microstructural changes in drilled surfaces, including damage zones and matrix fractures specific to AWJ processing. Multi-objective optimization using Genetic Algorithm is performed to enable flexible parameter selection and informed decision making, balancing machining efficiency and minimal damage.

How laser material processing can benefit from OCT technology

AbstractUltrashort‐pulse (USP) laser ablation enables the creation of freeform shapes that are challenging to produce with conventional optics manufacturing techniques. To maintain the industrial standards of many branches, it is crucial to not only consider material removal rates but also the surface quality and subsurface damage (SSD). This study investigates the SSD patterns generated in fused silica and quantifies key parameters such as the SSD depth by applying optical coherence tomography (OCT).

Performance analysis of turning operation parameters empirically on Delrin

Delrin is the best additional material for metals because of its inherent qualities, such as great wear resistance and tensile strength. The main aim of this work is to investigate how independent variables like feed rate, spindle speed, and depth of cut are significant for dependent variables such as surface roughness, temperature, stresses, and material removal rate on novel material Delrin. The independent variable ranges are selected based on tool and workpiece material combinations and machine tool specification as spindle speed 230 – 844 rpm, feed rate 0.5 – 1.5 mm/rev, and depth of cut 1 – 3 mm. Based on the L27 orthogonal array experimental plan 27 numbers of experiments are conducted by the design of experiment concepts. The theoretical investigation through response surface methodology is also conducted to establish how independent variables affected dependent variables when Delrin was being machined. The independent variable's significance is determined by the ANOVA table for all the considered responses. In addition to the considered flow of work, the experiential model is developed by the utilization of regression analysis. The developed models are confirmed by experimental data and the models have the best validation results with the experimental results.

Investigation of large-aspect ratio microgrooves on silicon nitride ceramic by WJALM

Silicon nitride (Si3N4) ceramic has excellent durability and superior outstanding mechanical properties, which makes it extensively applied in aerospace, biopharmaceuticals, semiconductors and optoelectronics. Nevertheless, the precise microfabrication of complex-shaped Si3N4 microgrooves, particularly those with large aspect-ratio (LAR) presents significant challenges, and traditional machining methods fall short in meeting the demanding criteria for high-precision applications due to the difficult-to-machine characteristics (e.g. high hardness, high strength and brittleness, etc.). In this research, waterjet-assisted laser machining (WJALM) is preferably adopted for LAR Si3N4 microstructures, which has demonstrated superiority in reducing thermal-induced defects of laser-only machining (LOM) with the water's impact and cooling effects. A comparative investigation of LOM and WJALM is initially conducted to evaluate the heat-affected zone (HAZ), geometric characteristics and sidewall surface quality of LAR Si3N4 microgrooves. Following that, the influence of waterjet and laser parameters on morphological characteristics for WJALM is studied through the control variable method. Results indicated that compared to LOM, the HAZ, material removal rate and sidewall surface quality of LAR microgrooves fabricated by WJALM were much superior. This research not only provides new strategies for Si3N4 microgrooves but also lays the foundation for the further development and industrial application of water-assisted laser technology.

Influence of different rare earth oxides on CNC ultrasonic machining of HP-HVOLF sprayed ceramics coating

The current study aimed at the optimization of process parameters for microchannel fabrication on thermal sprayed carbide coatings using rotary ultrasonic machining (RUSM). Rare earth oxides (REOs) such as La₂O₃, CeO₂, and Er₂O₃ have been incorporated into WC-Co-Cr coatings to enhance machinability and improve coating characteristics. The research has demonstrated that La₂O₃ doped coatings have significantly increased the material removal rate (MRR), with a 15 % improvement when compared to undoped coatings. Additionally, surface roughness has been reduced by 20 %, resulting in a smoother and more uniform finish. The inclusion of REOs has refined the microstructure of the coatings, yielding denser and more compact layers, which has reduced defects and improved the overall surface quality. Furthermore, the hardness of the coatings has been enhanced by 45 %, with La₂O₃ doped coatings achieving a maximum hardness value of 1313 ± 11 HV. The findings have highlighted the potential of REO doping to enhance the performance and efficiency of microchannel fabrication on WC-Co-Cr coatings using RUSM, contributing valuable insights to industrial applications.

Experimental investigation on micro-EDM hybrid drilling process

Micro-EDM drilling is highly appreciated to produce micro-holes on any type of conductive material. Several industrial fields use this technology thanks to its capability to realize very accurate machining. A greater use of micro-EDM drilling process is limited by its poor performance in terms of machining time. To overcome this limit, hybrid solutions are being tested. The idea consists of benefitting from the advantages of at least two technologies trying to overcome the limitation of each one of them. Typically, EDM is used as secondary operation and the process consists of executing the micro-hole on a pre-hole realized by another process like laser. In this way, both the process performance and the quality aspects are guaranteed. Aim of this work is the investigation of the behaviour of the micro-EDM drilling on a pre-hole. In fact, the presence of a pre-hole changes deeply the machining conditions especially in terms of the dielectric flushing. In order to understand how the pre-hole changes the performance of the EDM drilling process, several aspects were investigated: the effects of the diameter of the pre-hole, the behaviour of the type of electrode, the influence of the accuracy of centring operation on the pre-hole and the hole depth. Titanium alloy sheets were used to execute final hole using electrode diameter of 0.3 mm. The process was evaluated considering both the process performance and the accuracy of the machining. The study of the law of electrode motion along its Z axis was also used to gather process information. In general, working with pre-holes yields much better performances than traditional EDM drilling thanks to different level of debris contamination in the machining zone. It was found that increasing the dimension of the pre-hole, the Material Removal Rate undergoes little changes. The electrode type (cylinder or tubular) on the pre-hole does not have evident effects on the process performance but only on the geometrical characteristics. The misalignment of the final hole on the pre-hole can improve the debris flow making the process more efficient but only when a part of the pre-hole lays outside the final hole. Within the limit of this experiments, the hole depth does not affect the presented results.