Investigation of machining characteristics and surface integrity for trim cut WEDM of hybrid metal matrix composite [Al 6061, SiC, and TiB2]

Abstract

Abstract This study is focused on fabrication of Hybrid Al6061/SiC + TiB2 MMC by stir casting process, primarily to study the effect of two different reinforcement particles on mechanical properties and microstructure. Additionally, the assessment of surface integrity has been attempted after machining the composite by trim cut WEDM process. Five samples have been fabricated with varied weight fraction of SiC and TiB2 reinforcement, keeping total weight percentage of reinforcement particles fixed to 10%. It is observed that Hybrid MMC with composition Al6061 (90%), SiC (2.5%), and TiB2 (7.5%) shows better mechanical properties which is corroborated by both the optical microscopy and SEM. A screening experiment has been designed using fold over fractional factorial technique (with resolution IV), to investigate the parametric effects on surface integrity features, i.e., surface roughness, spark gap, and recast layer for trim cut WEDM operation. Peak current (I p) and pulse on time (T on) have been found to be the significant parameters for spark gap as well as surface roughness. It is observed that the trim cut operation improved the surface roughness and reduced it to 2.2 µm from 3.93 µm (after rough cut). Recast layer has been reduced to a value of 4.67 µm after trim operation, from 24.6 µm for rough cut. These findings suggest that trim cut strategy is very effective in improving the surface integrity of the rough-cut machined samples. It is also observed that thickness of recast layer is directly proportional to the discharge energy during trim cutting.

Keywords

• Stir casting
• Hybrid MMC
• Fold over fractional factorial design
• Trim cutting
• WEDM
• Optical microscopy