WEDM Characteristics of Stir-Cast Al-TiB2 Metal Matrix Composites

Abstract

This article presents an experimental investigation of the WEDM (Wire Electrical Discharge Machining) performance of Al-TiB₂ composites fabricated using ultrasonic vibration-assisted stir casting and containing four different weight percentages (1%, 2.5%, 4%, and 5.5%) of TiB₂ particles. Key machining parameters, namely pulse-on time, wire feed rate, and pulse-off time, are varied at three levels suitable for machining aluminium base material while minimizing wire breakage. Cutting speed, material removal rate, and kerf width are observed individually for each selected level of these process parameters. Surface features are assessed using SEM (Scanning Electron Microscope), EDAX (Energy Dispersive X-ray Spectroscopy), 3D optical surface profilometer, and optical microscopy. Notably, the roughness values are lower in the 4% and 5.5% TiB₂ composites compared to the base matrix. This reduction in roughness is due to the protective role of the particles, which shield the surface from melting during the WEDM process. Melting and re-welding phenomena were observed throughout the machining process. It is observed that higher pulse-on time generates harsh sparks, leading to rougher surfaces that include melted zones and pits. The WEDM operations performed on the 5.5 wt% reinforced composite surface result in a significant reduction in roughness, decreasing from around 5 µm to approximately 2.7 µm.