Experimental investigation of productivity and surface integrity features in trim cut WEDM operation of hybrid metal matrix composite

Abstract

Present study is focused on optimization of WEDM process parameters for increased productivity and improved surface quality of the machined surface of hybrid composite [Al6061 (90 %), SiC (2.5 %) and TiB₂ (7.5 %)] by utilizing the trim cut strategy. Effects of four factors namely, pulse on time (T_on), peak current (Ip), wire offset (WO) and rough-cut history (RCH) have been investigated on response characteristics namely, material removal rate (MRR), surface roughness (SR) and Recast layer (RL) thickness; using Box-Behnken design (BBD) for the experimentation. Three levels of RCH i.e., high, medium and low have been included to investigate the effectiveness of trim cut strategy for dealing with rough-cut surface under varied conditions. The optimized parametric setting has been obtained for multiple responses using desirability function. RCH is found to be most significant factor for MRR, while pulse on time (T_on) is found most significant for SR and RL. WO has been found to play an important role in controlling the thickness of RL. It is observed that after trim cut, surface roughness is improved for experiments conducted under high and medium levels of RCH. However, almost no improvement in SR is obtained for low level of RCH. Trim cut strategy is also found to be effective in reducing the thickness of recast layer, however, it is noticed that the percentage reduction in recast layer thickness for samples machined under high level RCH is greater than that for the other two levels of RCH.