Abdus Sabur

Effect of Peak Current on Material Removal Rate for Electrical Discharge Machining of Non-Conductive Al2O3 Ceramic

Electrical discharge machining (EDM) is a non-conventional machining process where materials are removed by the thermal energy exerted from series of electrical sparks. This process is applied for machining of non-conductive alumina (Al2O3). The workpiece is covered with the adhesive copper foil to initiate the initial spark between the workpiece and the tool electrode. A pyrolytic carbon (PyC) layer is generated on workpiece surface by dissociating kerosene dielectric after the machining of initial copper assisting electrode (AE) layer. In this study, experiments were performed by varying the peak current and keeping other parameters constant in order to investigate the effect of peak current on material removal rate (MRR) in EDM of Al2O3. The results showed that the lowest and the highest values of peak current were 1.1 A and 1.3 A, respectively. Material cannot be removed due to insufficient PyC layer generation for any values of peak current less than 1.1 A or more than 1.3 A. From the results, it is also observed that the MRR is increased when higher peak current values are used. MRR was found to be 0.052 mm3/min at peak current 1.1 A and it was found to be 0.132 mm3/min at peak current 1.3 A.

Effect of Micro-EDM Parameters on Material Removal Rate of Nonconductive ZrO2 Ceramic

Micro-electro discharge machining (micro-EDM) technique, an advanced noncontact machining process, is used for structuring of nonconductive ZrO2 ceramic. In this study copper foil as a conductive layer is adhered on the workpiece surface to initiate the sparks and kerosene is used as dielectric for creation of continuous conductive pyrolytic carbon layer on the machined surface. Voltage (V) and capacitance (C) are considered as the parameters to investigate the process capability of machining parameters in continuous micro-EDM of ZrO2. Different voltage pulses are studied to examine the causes of lower material removal rate (MRR) in micro-EDM of nonconductive ceramics. The results showed that in micro-EDM of ZrO2 MRR increases with the increase of voltage and capacitance initially, but decreases at higher values and no significant materials are removed at capacitances higher than 1nF.

Modelling of Material Removal Rate in EDM of Nonconductive ZrO2 Ceramic by Taguchi Method

Electro discharge machining (EDM) technique, a noncontact machining process, is applied for structuring nonconductive ZrO2 ceramic. A conductive layer of adhesive copper is applied on the workpiece surface to initiate the sparks. Kerosene is used as dielectric for creation of continuous conductive pyrolytic carbon layer on the machined surface. Experiments are conducted by varying the peak current (Ip), pulse-on time (Ton), pulse-off time (Toff) and gap voltage (Vg). Correlating these variables a mathematical model for material removal rate (MRR) is developed using Taguchi method. The optimized parametric conditions are determined for higher MRR through ANOVA and signal to noise (S/N) ratio analysis. The results showed that the Ip and Ton are the significant parameters of MRR in EDM for nonconductive ZrO2 ceramic. The model also showed that MRR increases with the increase of Ip and Ton, but the process is controlled by Ip as a whole.

Micro Electro Discharge Machining of Non-Conductive Ceramic

Electro discharge machining (EDM) as a die sinking process has taken off in 1943. Since then it was known as a non-conventional machining process and its application was limited for processing only electrically conductive materials. Later on, due to the widespread applications, this EDM process is considered conventional as usual. However, in the recent years EDM has gone through considerable changes especially with dielectric fluids, simple to complex geometry, meso to micro sized structures, nanometric surface finish, and so on. In addition, the application of EDM has also been extended for processing electrically semi-conductive and non-conductive materials like ceramics and composites. This paper discussed micro electro discharge machining of non-conductive ceramic materials. It includes detail process development, modelling of material removal rate and surface finish which include the effect of multi spark and random spalling conditions.