Experimental investigations of deposition conditions for saw wire fabrication by electrical discharge machining

This paper deals with fabrication conditions of a wire saw by electrical discharge machining (EDM). A deposition method by EDM with a compressed tungsten carbide (WC)-cobalt (Co) powder as an electrode has been proposed. In order to improve deposition performance, electrical conditions such as discharge current and open-circuit voltage for EDM were experimentally investigated together with core wire materials, fabrication pressure of the compressed electrode, and wire feeding speed. Cracked carbon coming from working oil by discharge was diffused into the wire, so that the carbon concentration becomes too rich and the wire embrittles. Consequently, stainless steel was preferable for this method. A thick layer was deposited at moderate current of 5 A without breaking of the core wire. A uniform layer was deposited on the wire over an open-circuit voltage of 260 V due to the discharge dispersion and over a compressing pressure of 490 MPa due to the uniform wear of the electrode. After the cyclic and diagonal sequences were compared for the deposition on a 0.2-mm stainless steel wire from four sides, the diagonal one was better because of no discharge concentration.