Electric Discharge Machining of NiTi Alloys by using Cryo-Treated Copper Electrode

摘要

NiTi alloys are one class of shape memory alloys. They find applications in manufacturing industries and medical fields. Due to striking properties of this alloy they are difficult to machine due to presence of intermetallic compounds, strain hardening effect and fragment of alloy adhered on the surface of the tool. Conventional machining of NiTi is associated with difficulties and electrical discharge machining (EDM) show high capability to machine NiTi. It is a substitute process to conventional processes. The aim of present study is to produce meso-scale holes on cryo-treated and untreated NiTi using cryo-treated electrolytic copper electrode on EDM machine. The effect of cryo treatment of copper electrode on material removal rate(MRR) and tool wear rate(TWR) is studied inconjuction with electrical parameters namely gap current, pulse on time and pulse off time. Experimental results showed an improved MRR in case of untreated NiTi and treated copper electrode for all these electrical parameters. It is observed that when both NiTi and copper are cryo-treated for all these electrical parameter MRR is low. With increase in gap current tool wear increase but tool wear is low when both NiTi and copper are treated. Tool wear is low when both NiTi and copper are treated with regards to pulse off time and it is high in case of pulse on time. Tool wear is less when untreated NiTi is machined by treated copper.