Optimization of Process Capability Index for Ultrasonic Machining of WC-Co Composite

In manufacturing industries, the demand of WC-Co composite is flourishing because of the distinctive characteristics it offers, such as; toughness (with hardness), good dimensional stability, higher mechanical strength etc. WC-Co composite materials are machined using conventional and non-conventional techniques. However, these techniques have their own limitations, in the perspective of deteriorated surface quality (cracks, heat affected zone, recast layer), high cutting forces and alteration of mechanical properties. The present investigation is aimed at studying the impact of different experimental conditions (by varying cobalt content, thickness of work piece, tool profile, tool material, abrasive grit size and power rating) on process capability of ultrasonic machining process for WC-CO composite material. The process capability index has been evaluated for the different experiments planned as per Taguchi L36 OA and further optimized as per DOE methodology. Significant factors for the index have been identified through Analysis of variance and the optimized process setting has been realized. it is concluded that evaluation of process capability index is of utmost importance for a mechanical energy based process like USM, where the dimensional inaccuracy such as hole oversize is significant and the machining databases are lacking any kind of information on it.