High-Speed End Electric Discharge Milling of Silicon Carbide Ceramics

Silicon carbide (SiC) ceramics have found a variety of engineering applications due to their superior properties. However, the manufacture of SiC ceramics is not an efficient process. A new process of machining SiC ceramics using end electrical discharge (ED) milling is presented in this research. End ED milling employs a turntable with several small cylindrical rods as the tool electrode, and uses a water-based emulsion as the machining fluid. This process is able to effectively machine a large surface area on SiC ceramic. The machining principle and characteristics of the technique are introduced. The effects of tool polarity, pulse on-time, pulse off-time, peak voltage, and peak current on the process performance such as the material removal rate (MRR), electrode wear ratio (EWR), and surface roughness (SR) have been investigated. In addition, the microstructure of the machined surface is examined with a scanning electron microscope and an energy dispersive spectrometer.