Papers by Keyword: Material Removal Rate (MRR)

Abstract: The ultra-thin 304 stainless steel sheet will be used in flexible displays for substrate material. In chemical mechanical polishing of ultra-thin stainless steel, the pH value of polishing slurry has an important influence on the material removal rate (MRR). In this paper, the influences of pH regulator in slurry on MRR had been studied in CMP of ultra-thin 304 stainless steel based on alumina (Al₂O₃) abrasive in acidic polishing slurry. The research results show that, in the same conditions, different pH value had a different chemical action mechanism and a different MRR. And also, different oxidant with pH regulator had a different chemical action mechanism and a different MRR. The research results can provide the reference for studying the slurry in CMP of ultra-thin stainless steel.

Abstract: Finishing process of sapphire wafer is meeting huge challenge to fulfill the strict requirement of high surface quality in semiconductor industry. Fixed abrasive process, although can guarantee the profile accuracy, leaves damaged layer on the surface or subsurface of sapphire wafer. Chemical mechanical polishing (CMP) is famous for providing great surface roughness, however, sacrifices surface geometrical accuracy. Therefore, a new chromium oxide (Cr₂O₃) sapphire grinding wheel based on chemical mechanical grinding (CMG) principle has been developed and its performance has also been put into examination. The experiment result has demonstrated that Cr₂O₃ possesses an outstanding potential in terms of a high material removal rate of sapphire wafer, meanwhile, largely reduces surface roughness from about 150nm to below 10nm in 1 hour. In addition, the design of experiment (DOE) has also been carried out to study the effect of influencing factors towards ultimate surface roughness of sapphire wafer. It reveals that the revolution speed of sapphire wafer bears twice greater influence towards surface roughness than the revolution speed of grinding wheel.

Abstract: In this investigation, a new approach is based on Grey Relational Analysis and Taguchi method to optimize the machining parameters with multi performance characteristics in WEDM of 304L SS. Experiments are conducted using Taguchi Quality Concept, L₉,3-level orthogonal array was chosen for experiments .The WEDM parameters namely pulse-on time (T_ON), pulse-off time (T_OFF), and wire feed (WF) on material removal rate (MRR) .The Grey Relational Analysis with multiple performance characteristics indicates that the pulse-on time (T_ON), pulse-off time (T_OFF) are the most significant factors . The optimum machining parameters have been identified by Grey relational analysis and significant contribution of parameters can be determined by analysis of variance (ANOVA). The confirmation test is also conducted to validate the test result. The results from this study will be useful for manufacturing engineers to select appropriate WEDM process parameters to machine 304L Stainless Steel.

Abstract: In this article, the effect of wire electrical discharge machining (WEDM) parameters such as pulse-on time (T_ON), pulse-off time (T_OFF), and wire feed (F) on material removal rate (MRR) and surface roughness in metal matrix composites (MMCs) consisting of aluminium alloy (A1356) silicon carbide (SiCp) and Mica is discussed. The Al 356 is reinforced with SiCp and Mica in the form of particulates. The experiments are carried out as per design of experiments approach using L9 orthogonal array. The optimum machining parameters have been identified by a composite desirability value obtained from desirability function analysis as the performance index, and significant contribution of parameters can then be determined by analysis of variance (ANOVA). Confirmation test is also conducted to validate the test result. Experimental results have shown that machining performance can be improved effectively through this approach. The results were analysed using analysis of variance and response graphs. It is found that different combinations of WEDM process parameters are required to achieve higher MRR and minimum surface roughness for composites. These results will be useful for manufacturing engineers to select appropriate WEDM process parameters to machine MMCs of Al 356 reinforced with SiC and Mica.

Abstract: This paper embarks the machining parameters of Turning by optimization using Taguchi’s approach. The optimization is very essential in order to obtain the expected surface quality. The results of cutting parameters of optimization is seen in the Surface Roughness, Tool wear and MRR of the material. The L18 Orthogonal array has been chosen for the optimization of Valve Steel SUH03.The uncoated carbide inserts were used and the four parameters Speed, Feed, Depth of Cut and Nose Radius has been taken as input parameters. The Signal to Noise ratio and Analysis of Variance software has been analyzed using Minitab software through which the optimal cutting parameters of the best surface roughness, tool wear and MRR has been obtained. The final results have been compared by the Gray relational analysis to find the optimum machining conditions of all the parameters.

Abstract: In this paper, lapped C-face of single crystal SiC wafer was irradiated by femtosecond laser. Chemical mechanical polishing (CMP) was then carried out to polish the irradiated SiC C-face. The authors compared the results of femtosecond laser-assisted CMP process. A white-light interferometer was used to investigate the surface morphology of the processed SiC substrate before and after laser irradiation. It was found that the material removal rate (MRR) of the irradiated substrate is about 3 times higher than that of the substrate not treated by femtosecond laser. In addition, lower surface roughness was realized after femtosecond laser assisted CMP process.

Abstract: In present scenario most of airframe components employ aluminum alloy materials having wall thickness of 1.2 to 3mm. With advancement of manufacturing techniques such as high speed machining, it is possible to machine components with wall/floor thickness up to 0.3 to 0.5 mm with high aspect ratio. The aim of making such parts is to reduce weight of payload. The machining of monolithic structure involves removing of material up to 95% from the raw material. The objective of the study is to achieve maximum material removal rate without compromise on geometry, dimensional accuracy while machining the part. This paper proposes a working methodology for high speed machining which includes efficient process planning, based on static and dynamic analysis. This paper provides insight knowledge of selection of cutting tool, fixture design, clamping method, cutting process parameters; machine tool and computer aided manufacturing (CAM) strategy, optimum stock for minimal bending and distortion. This technology has been demonstrated in hexagonal test specimen of 0.5 mm thin wall and also proven on the indigenous developed global positioning system (GPS) components.

Abstract: In the present paper, a two dimensional numerical model has been developed using the finite element method (FEM) for predicting the material removal mechanism in micro EDM process in single spark with the assistance of magnetic field. The work piece material selected for the present study is grade 5 titanium material. The model developed by not considering magnetic field, first calculates the temperature distribution in the work piece material using the commercial software ANSYS. The crater shape is developed using the simulated temperature profiles to estimate the volume of material removed in a single spark, by considering the melting point and vaporization temperature. The model has been validated by comparing the theoretical MRR with the experimental results which is already established. The use of magnetic field which can provide an additional Lorentz force in the melt pool could aid in ejection of material from the discharge crater, thereby improving MRR. This concept is established through the coupling of magnetic and structural fields.

Abstract: Many advanced machining processes have higher initial investment, maintenance and tooling costs. In these circumstances micro electrochemical machining [µECM] processes meet the requirements with better efficiency and economy. The micro electrochemical machining process parameter such as electrolyte concentration, machine voltage, and pulse on time and duty factor are optimized with considerations of the multiple performance characteristics such as material removal rate (MRR) and overcut. Increase in electrolyte concentration considerably improves MRR but yields a poorer over cut. Increased machine voltage serves to increase both MRR and over cut significantly. Increased pulse on time and duty factor did not have notable impact on MRR and overcut. Less concentration of sodium chloride [NaCl] is sufficient for machining compared with sodium nitrate [NaNO₃]. Higher MRR and better over cut are achieved with sodium chloride and moreover it is more economical than sodium nitrate.

Abstract: Beryllium copper possesses high strength which produces severe problem of surface integrity and tool wear during machining by conventional machining process. Electrical discharge machining is a practically viable option to solve this problem. The present study investigates the effect of cryogenic treatment of work part along with gap current and external magnetic field on material removal rate (MRR) and tool wear rate (TWR). Blind 3 mm square holes were produced using electrolytic copper tool electrode to machine cryo-treated BeCu and untreated BeCu. Gap current is varied from 8 A to 16 A in a step of 2 amperes and magnetic strength is varied from 0 to 0.496 T in a step of 0.124 T. Based on the experimental results it was found that MRR increases with increase in gap current for both untreated BeCu and treated work part. Plotted graphs of cryo-treated work part showed high values of MRR in comparison to untreated work part. TWR increases for both treated and untreated BeCu work part with increase in gap current. But the TWR was less for cryo-treated work part in comparison to untreated work part. MRR and TWR increases for both treated and untreated BeCu work part with increasing magnetic strength. Again the MRR was found higher with lower TWR for treated workpiece with regard to magnetic strength. Thus it can be concluded that cryogenic-treatment with magnetic strength improves EDM machining efficiency.