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Novel polyelectrolyte–Al2O3/SiO2 composite nanoabrasives for improved chemical mechanical polishing (CMP) of sapphire
摘要： A new type of polyelectrolyte–Al2O3/SiO2 composite nanoparticle with excellent dispersibility and superior polishing performance was successfully fabricated using a facile method. Silica acted as a bifunctional molecule by attaching to alumina via covalent bond and adsorbing polyelectrolytes by electrostatic interaction. The material removal rate of the polyelectrolyte–Al2O3/SiO2 abrasive was 30% higher than that of the pure Al2O3 abrasive. In addition, the sapphire surface was much smoother. The material removal mechanism was investigated during CMP using the microcontact and wear model. The enhanced removal rate was mainly attributed to the well-dispersed particles, which can accelerate mechanical removal process. The remarkably smooth surface was due to the decrease in penetration depth of the abrasive into the wafer. The results of this study provided a feasible strategy to satisfy the high efficiency and damage-free polishing requirements for sapphire planarization.
关键词： chemical mechanical polishing,composite abrasives,polyelectrolyte,surface roughness,sapphire,material removal rate
更新于2025-09-23 15:22:29
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Modeling and multiresponse optimization of cutting parameters in SPDT of a rigid contact lens polymer using RSM and desirability function
摘要： Amidst different conventional contact lens manufacturing techniques, single-point diamond turning (SPDT) is one of the recently developed ultra-high precision machining techniques employed in the fabrication of advanced contact lenses due to its capability of producing high optical surfaces of complex shapes and nanometric accuracy. SPDT is regarded as an effective process for the generation of high-quality functional surfaces in optical industries. However, despite advances in the ultra-high precision machining, it is not always easy to achieve a high-quality surface finish with maximum productivity. Machining parameters, namely cutting speed, feed rate, and depth of cut, play the lead role in determining the machine economics and quality of machining. The present study focuses on the determination of the optimum cutting conditions leading to minimum surface roughness as well as electrostatic charge and maximum productivity, in SPDT of the polymethyl methacrylate (PMMA) contact lens polymer using monocrystalline diamond cutting tool. The optimization is based on the response surface methodology (RSM) together with the desirability function approach. In addition, a mathematical model is developed for surface roughness (Ra), electrostatic charge (ESC), and material removal rate (MRR) using RSM regression analysis for a rigid contact lens polymer by the Design-Expert software. RSM allowed the optimization of the cutting conditions for minimal surface roughness, electrostatic charge, and maximal material removal rate which provides an effective knowledge base for process parameters, to make its enhancement of process performance in SPDT of contact lens polymer.
关键词： Electrostatic charge,Response surface methodology,Material removal rate,Surface roughness and optimization,PMMA contact lens polymer,Single-point diamond turning
更新于2025-09-23 15:22:29
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Spherical Mirror and Surface Patterning on Silicon Carbide (SiC) by Material Removal Rate Enhancement Using CO2 Laser Assisted Polishing
摘要： Silicon carbide (SiC) is well known as an excellent material for high performance optical applications because it offers many advantages over other commonly used glasses and metals. The excellent attributes of SiC include high strength, high hardness, low density, high thermal resistance, and low coefficient of thermal expansion. The effect of CO2 laser and its tool path on SiCwere investigated. The process started by creating laser pre-cracks on the desired pattern. Subsequently, laser assisted polishing was conducted on the same tool path. The surface showed a sharp increase in material removal in the areas with laser pre-cracks. This high difference in material removal was used not only to fabricate a ? 1100?mm concave mirror with 127?μm in depth but also to generate macro and micro patterns. Grooves from 2?mm to 200?μm in width and 5?μm to 20?μm depth were successfully generated.
关键词： Material removal rate,CO2 laser,Patterning,Polishing,Hybrid
更新于2025-09-23 15:21:01
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Deep and high precision cutting of alumina ceramics by picosecond laser
摘要： Ceramics possess high thermal and chemical resistance, low density, and high compressive strength; however, the machining complications imposed by their inherent brittleness limit their range of applications. Laser cutting technology can offer an automated manufacturing technique for machining these brittle materials. In this paper, a laser cutting method, so-called wobbling, was developed for performing deep, high precision, and defect-free laser cutting of industrial grade alumina ceramics. This work explored picosecond laser process parameters such as focal position, linear speed, and wobble amplitude in order to control cut depth and optimize cut quality in terms of kerf width, kerf taper, surface cleanness, while avoiding crack formation. The morphology and cut quality were evaluated using 3D laser scanning microscopy and scanning electron microscopy (SEM). Picosecond laser cutting process parameters were optimized, achieving a maximum material removal rate of ~10 mm3/min. It was shown that the laser cutting process developed via these experiments represents an effective and efficient manufacturing tool that can be incorporated in engineered net shaping systems.
关键词： Laser cutting,Material removal rate,Ablation,Ultrafast laser micromachining,Alumina ceramics
更新于2025-09-23 15:21:01
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Laser cutting optimization model with constraints: Maximization of material removal rate in CO <sub/>2</sub> laser cutting of mild steel
摘要： Taking full advantage of what laser cutting technology offers in terms of achieving superb quality cuts at low cost and high production rates requires the optimization of laser cutting parameters. This implies the need to formulate and solve different laser cutting optimization problems. In this article, an optimization model for CO2 laser cutting of mild steel is developed. The laser cutting optimization problem was explicitly formulated as a single-objective optimization problem with five non-linear constraints of the equality, inequality and range type. The goal was to determine the laser cutting parameter values so as to maximize the material removal rate while simultaneously considering practical process constraints related to dross formation, kerf width, perpendicularity deviation, surface roughness and severance energy. Two crossed experimental designs of different resolutions were performed in order to define six mathematical models, which were used in the formulation of the optimization problem. For the purpose of optimization, the exhaustive iterative search algorithm was applied, since it determines solutions whose optimality is guaranteed in the given discrete space of input variable values. The practical usability of the developed laser cutting optimization model and the effectiveness of the applied optimization approach were proved while solving a real case study aimed at the optimization of laser cutting parameters for cutting parts for the furnace industry.
关键词： mild steel,CO2 laser cutting,optimization model,material removal rate,non-linear constraints
更新于2025-09-23 15:19:57
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Improvement of ablation capacity of sapphire by gold film-assisted femtosecond laser processing
摘要： Sapphire is widely used in civilian and military equipment owing to its superior optical and mechanical properties. Femtosecond laser has been demonstrated to be an effective tool to process sapphire material. However, the direct processing of sapphire by femtosecond laser still meets some challenges, such as poor ablation morphology and low laser energy absorption. In this work, femtosecond laser processing of sapphire coated with a 12-nm-thick gold film (Au-coated sapphire) has been investigated. The experimental results have revealed that the ablation morphology of Au-coated sapphire has been improved, featuring fewer molten materials and thermal cracks, as well as regular crater shape and uniform periodic surface structures. It has also been found that, under 100 shots condition, the threshold fluence of Au-coated sapphire is reduced by about 56% compared to that of uncoated one. Meanwhile, the incubation effect of Au-coated sapphire is stronger than that of uncoated one. We also illustrate that the material removal rate of Au-coated sapphire is increased up to about two times higher than that of uncoated one. In order to reveal the effective mechanism of the gold film in the laser processing of sapphire, the energy transfer process among incident photons, free electrons and sapphire lattice phonons was studied. Our study provides a guidance for improving the laser ablation capacity of sapphire.
关键词： Gold film,Sapphire,Material removal rate,Ablation morphology,Femtosecond laser processing
更新于2025-09-19 17:13:59
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Machinability of titanium alloy through laser machining: material removal and surface roughness analysis
摘要： Laser milling is a competent precision process especially when the work material is hard-to-machine such as titanium alloys. While performing the laser milling, a slight change in one of the laser parameters results in an abrupt change in the machining outcomes. A close match between the designed and the machined geometries is the essence of precision machining. A precise control over the material removal rate per laser scan is highly desirable but difficult to achieve. The difficulty level becomes higher if high surface finish is desired alongside the precision machining. In this research, the objective was set to perform the laser milling on titanium alloy (Ti-6Al-4V) with 100% control over material removal rate (MRR) per laser scan and minimum surface roughness (SR). Influence of the five laser parameters (laser intensity, pulse frequency, scan speed, layer thickness, and track displacement) on MRR and SR has been deeply investigated. Significance of each laser parameter is evaluated through ANOVA. Mathematical models for both the responses are developed to estimate the resulting responses at any parametric setting. Models have also been validated through confirmatory tests. Optimization of laser parameters is of great importance to remove the material exactly equal to the desired depth with minimum surface roughness. Therefore, the optimized combinations of laser parameters have been proposed which ensure the conformance of 100% MRR and minimum surface roughness with composite desirability > 0.9. Confirmatory experiments revealed that the optimized parameters are capable to produce the laser milling results as per the models’ predicted results. Additionally, the microstructure of the subsequent layers below the milled area has also been examined and compared with the microstructure of the bulk Ti-6Al-4V. By the use of optimized parameters, microstructure of the sub-layers remains unchanged as compared with the microstructure of the base metal. No evidence has been found altering the microstructure of the sub-layers.
关键词： Laser milling,Titanium alloy,Mathematical model,Surface roughness (SR),Optimization,Material removal rate (MRR)
更新于2025-09-16 10:30:52
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Prediction of surface roughness and material removal rate in laser assisted turning of aluminium oxide using fuzzy logic
摘要： Processing of ceramics with good surface integrity and high material removal rate is a challenging task in the manufacturing industry. Laser assisted machining (LAM) is one of the benchmark technique currently used in industry to process difficult to machine materials. In LAM, laser is used as source to heat the work piece and simultaneously remove the softened material by cutting tool without changing the material microstructure. Since many process parameters are involved in LAM, experimental investigation of processing of ceramics is expensive. So the main objective of this present work is to develop an Artificial Intelligence model to understand the process mechanics and for the prediction of surface roughness and material removal rate (MRR) during laser assisted turning of Aluminium oxide using fuzzy logic. Input parameters are assumed as triangular and Gaussian function and output parameters are assumed as trapezoidal function. It is inferred that increase in cutting speed and pulsed frequency of laser, there is an improvement in surface finish, whereas increase of feed rate results in deterioration of surface integrity. The material removal rate is directly proportional to feed, speed, depth of cut and pulsed frequency of laser. There is a better agreement between experimental and fuzzy model values. The proposed model predicts the surface roughness and MRR with prediction error of 15.76 and 7.69 % respectively.
关键词： material removal rate,Laser assisted machining,fuzzy logic,surface roughness,Ceramics
更新于2025-09-12 10:27:22
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State of the Art on Laser Assisted Electrochemical Machining
摘要： Laser Assisted Electrochemical Machining (LAECM) has proven its advantages and applications over almost all the range of conductive materials. It offers its adroitness to generate simple shapes to complex shapes from macro to micro machining. Laser assisted ECM is a hybrid approach of machining which has been manifested to obtain improved results in terms of surface integrity, thermal damage, geometrical tolerance and material removal rate. Laser assisted Electrochemical Machining (LAECM) is a hybrid machining process in which laser enhances the electrochemical dissolution process by increasing the temperature and hence the current density of the electrolyte. Laser helps to remove material from the particular machining zone and stray machining effect is reduced and thus improves the precision and efficiency of LAECM, also productivity. New route of laser assisted hybrid machining processes has been built in the past decade by few of the researchers to reduce the intrinsic problems of ECM. This paper reviews on the investigation into LAECM process. The article also highlights various possibilities and applications of LAECM process. There are various challenges in LAECM process which have been also discussed in this paper.
关键词： Laser Assisted Electrochemical Machining,electrochemical dissolution,material removal rate,LAECM,hybrid machining
更新于2025-09-12 10:27:22
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Performance evaluation and multi-response optimization of grinding-aided electrochemical discharge drilling (G-ECDD) of borosilicate glass
摘要： Machining of advanced glass ceramics is of great importance and is a challenging task for the modern industries. In this study, a new hybrid technique of grinding-aided electrochemical discharge drilling (G-ECDD) is attempted which combines the grinding action of a rotating abrasive tool and thermal melting action of electrochemical discharges to perform drilling of borosilicate glass. G-ECDD is performed using a normal electrochemical discharge machine set-up with a provision for using a rotating diamond-coated drill tool. The tool used is a hollow diamond core drill rather than the traditional solid abrasive tool. A spring-fed tool system was designed and developed to provide the tool-feed movement which will also help to maintain a balance between grinding action of diamond grits and thermal melting action of discharges. Preliminary experiments are conducted to identify the optimum spring force of the spring-fed system and tool rotational speed which can facilitate a balanced ECDM and grinding action for material removal. The effect of machining parameters like voltage, duty ratio, pulse cycle time and electrolyte concentration on material removal rate (MRR) and hole radial overcut (ROC) is investigated using response surface methodology (RSM). Duty ratio and voltage are found to be the most significant factors contributing MRR. Voltage and pulse cycle time are identified as the main factors controlling radial overcut of the drilled holes. Second-order regression models for MRR and ROC are developed using the data collected from the experiments using RSM. Grey relational analysis was used to optimize this multi-objective problem. A voltage of 90 V, duty ratio of 0.7, cycle time of 0.002 s and an electrolyte concentration of 3.5 M are found to be the best combination for optimizing the responses. Deterioration of bonding material and dislodging of diamond grits are found to be the major modes of tool wear during G-ECDD. The use of high-frequency pulsed DC increased the tool wear rate due to the less time available for heat dissipation between discharge cycles. Moreover, the wear at the end face of the tool will be accelerated due to the concentration of current density at edges during high-frequency operation. From the microscopic images of the machined surface, the material removal mechanisms involved in G-ECDD are found to be a combination of thermal melting by discharges, grinding action of diamond grits and high-temperature chemical etching effect of the electrolyte.
关键词： Electrochemical discharge machining,Response surface methodology,Tool wear,Radial overcut,Grey relational analysis,Material removal rate,Material removal mechanism,Grinding
更新于2025-09-11 14:15:04