Electro-discharge machining performance of TiCN-based cermets

Abstract

The present investigation aims at evaluating the die sinking electro-discharge machining (EDM) performance of TiCN-20 wt.% Ni cermets containing 10 wt.% of different secondary carbides: WC, NbC and TaC. Such performance is assessed in terms of making cavity of 1 mm depth on a commercial high speed tool steel (HSS). The material removal rate (MRR) is found to be higher for TiCN-20 wt.% Ni cermet; however tool wear ratio (TWR) is lower for TiCN-20Ni-10TaC cermet. The quality of cermet tool surface has been quantitatively assessed using surface roughness tester and it was observed that the roughness (Ra or Rz) of TiCN-20Ni-10TaC cermet tool surface is lower, when compared with that of other investigated cermets. SEM-EDAX analysis of EDM surfaces reveal melting and evaporation of the binder as well as pull-out and spalling of brittle carbonitride/carbide grains as the dominant wear mechanisms. The layer formation due to solidification of molten layer and/or transfer of material from workpiece is commonly observed for all the cermet tool surfaces. © 2006 Elsevier Ltd. All rights reserved.