An experimental investigation for electric discharge milling of SiC ceramics with high electrical resistivity

Silicon carbide (SiC) ceramics have been widely used in modern industry. However, the beneficial properties of high hardness and high strength cause problems in shaping SiC ceramic blanks. Diamond grinding is one of the most commonly used techniques for SiC ceramic blanks shaping but it is costly and inefficient. Wire electric discharge machining and electrical discharge machining promise to be effective and economical techniques for the production of tools and parts from conducting SiC ceramic blanks with maximum electrical resistivity of 100 Omega cm. However, these electrodischarge machining methods of machining the SiC ceramics with high electrical resistivity shows low efficiency. Employing a steel toothed wheel as the tool electrode, SiC ceramics with electrical resistivity of 500 Omega cm are machined by electrical discharge milling in this paper. The process is able to effectively machine a large surface area on SiC ceramics with high electrical resistivity, and effectively machine other advanced materials with high electrical resistivity such as polycrystalline diamond, and cubic born nitride. The effects of emulsion concentration, milling depth, rotational speed of the tool, tooth number of the tool, and tooth width of the tool on the process performance have been investigated. (C) 2008 Elsevier B.V. All rights reserved.