Multi-response optimisation for turning of magnesium alloy with untreated and cryogenic treated carbide inserts by grey relational analysis

This research work includes an extensive experimental analysis to explore the significance of cryogenic treated (CT) and untreated (UT) carbide cutting inserts on the machinability of AZ91D Mg alloy. A Taguchi L-18 orthogonal array is employed to gather data for the analysis. Grey relational analysis (GRA) with both, equal weight (EqW) method along with entropy based weight method (EWM) are utilized to optimize the parameters of performance measures viz. surface roughness (Ra), cutting-tool temperature (T), cutting-force (Fz) and tool-wear (V-B). CT cutting inserts yield better results than untreated one. The GRA results provided the optimal parameter combination for both types of weight-allocation methods as 80 m/min cutting speed, 0.5 mm depth of cut, 0.1 mm/rev feed for CT cutting insert. Confirmation test evidenced that, Ra, Fz, T and V-B values are considerably reduced by 20%, 12%, 10% and 46% respectively while machining with cryogenic treated tool (CTT).