Cryogenic treatment analysis of electrodes in wire electric discharge machining of squeeze casted Al2024/Al2O3/W composite

Abstract

Peculiar characteristics of squeeze casted hybrid aluminum matrix composites (AMCs) enable it as an appropriate candidate for various manufacturing applications but also make their machining challenging. For that reason, wire electric discharge machining (WEDM) has been preferred over conventional machining processes for the cutting squeeze casted Al2024/Al2O3/W hybrid composite in this study. The presence of nanoparticles in the material affects the machining performance of wire electrodes. Therefore, molybdenum and zinc-coated wires have been chosen, and cryogenic treatment has been applied to improve their machining performance. To analyze the effects of cryogenic treatment, the machining efficiency of cryogenic treated (CT) wire has been compared with non-treated (NT) wire. Besides wire type, four key input variables including pulse duration (TON), wire feed rate (FR), wire runoff speed (SW), and wire tension (TW) have also been optimized to improve the imperative response measures including cutting speed (CS), surface roughness (SR), and kerf width (KW). Microstructural analysis of NT wire depicts a high concentration of micro-voids, micro-cracks, and deep craters, while the surface of CT wire has been observed relatively fine after the machining. Comparative analysis of both wire electrodes has declared that CT wire yields 26.96% and 15.10% superior results for CS and SR respectively, and 6.92% deprived results for KW than NT wire. Grey relational analysis (GRA) has been practiced for multi-objective optimization and presented TON = 3 μs, FR = 13 m/min, SW = 11 m/min, and TW = 10 g as an optimal set of input variables to achieve 75.1% and 72.5% overall results with NT and CT wire, respectively.