Impact of Electrical Process Parameter in Electrochemical Micromachining of Nimonic 75 Alloy

Electrochemical micromachining is one among the widely known method for machining micro holes in electrically conductive, hard to cut materials. As nimonic 75 alloy can withstand alternate cooling and heating conditions, it finds application in aero combustor liner. In this study, solid tungsten carbide (500µm) was selected as the tool to produce micro holes in the work-piece (nimonic 75 alloy). As pulsed current, results in more confined dissolution, trials were performed by changing electrical process parameter such as duty cycle, pulse on period and pulse off period and their effect on MRR and dimensional deviation were studied. Employing TOPSIS, lower values of duty cycle and pulse on period was desirable for the production of holes with better geometrical features and the similar was found to be in concurrent with SEM images.

Electrochemical ECG grinding of ceramic and tungsten sinter

The article describes a process of electrochemical grinding (ECG – Electrochemical Grinding) with a rectangular diamond grinding wheel made of ceramic – tungsten frit. Treatment of this type of material is very difficult, not only because of adverse physical properties of material itself but also due to very high requirements resulting from conditions of exploitation of a product. In discussed case, the process was carried out for a workpiece consisting of 8 tiles with a total area of about 110 cm2, fastened by screwing to a machine tool table. The article analyses a course of a chemical process, presenting chemical reactions and the course of an electrical process, closely related to a flow of electric current. Particular attention was paid to the flow of electric current as a function of changes in an active surface, understood as a geometric surface through which the electric current can flow. The results of calculation for this surface and an example of a shape of the recorded current waveform are shown. The presented results were used in construction of a control system based on maintaining a constant density of the working current.