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Finishing of silicon wafers is a billion dollar global business. The present process chain consists of several processes, which lead to long production times and increase the cost of the finished materials. In the recent years, several processes have been experimented as an alternate process for finishing substrate wafers with stringent specificati...
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Context 1
... Wear mechanism of the ELID grinding wheels Fig. 3 shows the combined wear mechanism during ELID grinding. The zone AB is named as the oxidation zone, where the bond material is oxidized due to electrolysis (where the wheel is covered by the electrode). The zone CD is named as wear zone where the wheel is in contact with the workpiece. The thickness of the oxidized layer on the wheel ...
Context 2
... during ELID grinding. The zone AB is named as the oxidation zone, where the bond material is oxidized due to electrolysis (where the wheel is covered by the electrode). The zone CD is named as wear zone where the wheel is in contact with the workpiece. The thickness of the oxidized layer on the wheel surface traced by a point ''P'' is shown in Fig. 3. The thickness of the oxidized layer produced during electrolysis is dependent on the bond material of the grinding wheel and the electrical parameters used for electrolysis (voltage, current and duty ratio). Among the bond materials, the cast iron bonded wheels produce a 100-200-mm-thick oxidized layer. However, the maximum thickness ...
Context 3
... actual wear rate of the ELID wheel is the difference between the wear rate of the oxidized layer at the grinding zone CD and the oxidation rate of the bond material at the electrolytic zone AB as shown in Fig. 3. The actual wear rate of the ELID dressed grinding wheel can be written ...
Citations
... The wheel radius wear leads to a deterioration of surface form accuracy while the grit wear results in a low grinding efficiency due to frequent dressing and truing [3,4]. As a result, many innovative processes such as ultrasonic assisted grinding [3,5], electrolytic in-process dressing (ELID) grinding [6,7], and electrical discharge diamond grinding [8] have been developed recently to solve the problem of wheel wear using an additional in-process dressing. In those processes, the grinding wheel will possess different wear behaviors and influences on the grinding performances. ...
Diamond wheel wear is the greatest challenge for the high-efficiency grinding of SiC mirrors due to the need for the frequent dressing of the wheel. To realize the dressing of the diamond wheel in the process, the electrical discharge diamond grinding (EDDG) that combines conventional grinding (CG) and electrical discharge machining (EDM) was used to machine the mirror material of reaction-bonded silicon carbide (RB-SiC) considering its conductivity. However, the diamond wheel will experience quite different wear behaviors from those in the CG process due to the additional electrical discharge action in the EDDG process. As a result, different grinding performances will also be obtained. In this paper, the wheel wear behavior and its influence on grinding performance were investigated by a comparing test with the CG process in continuous EDDG of RB-SiC. The wear behavior and mechanism of the diamond wheel were investigated by a combination of morphology detection and spectra analysis. To explore the influence of wheel wear on grinding performance, the material removal rate (MRR), grinding ratio (GR), grinding force, and surface roughness were discussed based on the wear regulation of the diamond wheel varied with processing time. The result revealed that the electrical erosion was mainly responsible for the different wear behaviors and mechanisms of the diamond wheel in the EDDG process. Due to the dressing effect and material removal caused by discharge sparks, higher MRR, lower GR, lower grinding force, and lower surface roughness were obtained in the EDDG process.
... Therefore, during ELID grinding, the dressing parameters could be adjusted according to the wear of the grinding wheel, thus avoiding excessive dressing of the grinding wheel. In addition to the grinding parameters, the oxidefilm state depends mainly on the metal bond, electrolyte, and power supply [24,25]. In the ELID grinding process, the metal bond and electrolyte characteristics are difficult to change; however, the power supply can be easily adjusted in real time. ...
... As can be observed from Eq. (28), under the cut-in ELID grinding condition, the oxide-film width is equal to the groove arc length. According to Eqs. (24) and (28), the oxide-film coverage area can be derived as follows: ...
... As can be observed from Eq. (34), under the condition of ELID grinding with workpiece swing, the oxide-film width is equal to the sum of the groove arc and swing arc lengths. According to Eqs. (24) and (34), the coverage area of the oxide film can be derived as follows: ...
This paper proposes a modeling method for oxide-film thickness to determine the quantitative relationship between the current and oxide-film thickness in electrolytic in-process dressing (ELID) grinding with workpiece swing. Using this method, the generation thickness of the oxide film per unit time was calculated based on Faraday’s law. The oxide-film thickness was calculated using current integration to determine the quantitative relationship between current and oxide-film thickness. Based on the ELID grinding experiment with workpiece swing, the influence of different swing parameters on the oxide-film thickness was analyzed, and the formation mechanism of the oxide film was obtained. The calculation results indicated that as the current decreased from 2.96 to 0.17 A, the oxide-film thickness increased from 0 to 52.79 μm. The experimental results indicated that as the swing amplitude increased from 10° to 30°, the current increased from 1.45 to 2.51 A, and the oxide-film thickness decreased from 33.89 to 24.58 μm. As the swing angular velocity increased from 5 to 15°/s, the current increased from 1.42 to 2.33 A, and the oxide-film thickness decreased from 34.15 to 26.68 μm. Elucidation of the oxide-film formation mechanism can provide a theoretical basis for improving the surface quality of arc grooves.
... The wheel is dressed intermediately when a certain amount of oxidized layer is removed from the wheel especially during grinding. The thickness of the oxidized layer produced is always found to be greater than the thickness of the bond material, and hence the reduction in wheel diameter is not expected to be as great as the wear of conventional grinding wheels [15]. ...
... Wear mechanism of ELID grinding wheel[15] ...
Smooth surfaces are generally considered as a symbol of high quality. Deterministic microgrinding is one of the methods for finishing non-axis symmetrical components. ELID Grinding is one such a process which uses metal bonded wheels of very fine abrasive grits to perform deterministic Grinding.
Electrolytic In-Process Grinding (ELID) is an advanced grinding process that carries out in situ dressing of the grinding wheel using an electrochemical reaction, i.e. anodic dissolution. This process is targeted to achieve the final finished product by eliminating subsequent finishing processes such as polishing and lapping. The process mainly aims for hard and brittle materials to achieve ductile mode cutting with the best cutting parameters, and by doing so to achieve the nano-level surface finish. The typical grinding particle size of the ELID grinding wheel varies from 1 to 5 µm. A characteristic ELID wheel is metal bonded which is used as an anode. There is another electrode which usually used as the cathode, and a liquid is flown between the anode and the cathode, which functions both as grinding fluid and electrolyte. A DC pulsed power supply is generally used as the power source for the electrolytic in-process dressing of the grinding wheel. This chapter will shed light on the history, fundamental and the current status of the ELID grinding related researches.
The groove profile of ball-bearing raceway is of vital importance to ensure the bearing transmission accuracy. It is an attempt to apply electrolytic in-process dressing (ELID) groove grinding for the ball-bearing raceway finishing process. The wear rate of the grinding wheel is directly related to the profile accuracy of the bearing raceway. In order to maintain a high-forming accuracy, the interrupt truing has to be performed at the grinding interval. However, how to rationally plan the grinding interval for high-forming accuracy is hard to resort to the general concept of the wear of the grinding wheel. This study recorded the raceway profile variation on axial direction and radial direction by monitor points. The results show that the raceway profile variation (monitor points) on the axial direction could be omitted, because it is far less than the profile variation (monitor points) on radial direction. An evaluation method was proposed to plan the interrupt truing based on the raceway profile variation (monitor points) on radial direction. Finally, the feasibility of the proposed evaluation method was verified by the experimental results. The evaluation method of forming accuracy could provide a reference for selecting the truing interruption during ELID groove grinding process. The approach that incorporates the interrupt truing with the ELID groove grinding enriches bearing manufacturing method. The ELID groove grinding has a great potential for application in precision machining of ball bearing ring raceway.
This paper introduces the potential feasibility that ELID (Electrolytic In-Process Dressing) grinding replaces superfinishing in bearing manufacturing. But ELID grinding will bring new challenges. Different regions present distinguish surface profile due to the non-uniform contact in ELID groove grinding. However, few reports explaining the non-uniform contact are available. This article explores the mechanisms of the non-uniform contact during ELID groove grinding. Experiments on the non-uniform contact between bearing raceway and grinding wheel have been carried out under different conditions. The results show that non-uniform contact exists in ELID groove grinding process and it exerts influence on the profile of the raceway surface. Non-uniform contact influences the Rsk and Rku value all the time, but it influences the Ra value occasionally. Improvement strategies of eliminating the non-uniform contact are also discussed based on the experimental study.
