Surface Characteristics of EDMed Titanium Alloy and AISI 1040 Steel Workpieces Using Rapid Tool Electrode

Abstract

Recently, additive manufacturing-based rapid tools are conveniently used in electrical discharge machining (EDM) process because complex-shaped tools can be produced in less time as compared to various conventional and nonconventional tool-making processes. However, sustainability of a rapid tool in terms of electrical and mechanical environment experienced in EDM process needs to be evaluated before recommending for real application. To address this issue, performance of AlSi10Mg tool manufactured by selective laser sintering process, a rapid prototype (RP) process, is compared with conventional copper and brass tools while machining titanium alloy and AISI 1040 steel in EDM process using EDM-30 oil as dielectric medium. Specifically, influence of EDM variables such as pulse-on-time (Ton) and discharge current (Ip) on performance measures like average surface roughness of machined surface (Ra), surface crack density, white layer thickness and micro-hardness of white layer has been studied. The study indicates that tool type is the most influential parameter followed by discharge current and pulse-on-time for both the workpiece materials. Superior surface characteristics can be obtained using AlSi10Mg RP tool at low level of parametric setting of discharge current and pulse-on-time. The machined surface by different tools is examined by scanning electron microscope to observe surface cracks. Energy-dispersive X-ray spectroscopy analysis reveals transfer of tool materials into the machined surface resulting in increase in percentage of carbon and oxygen on the machined surfaces. Finally, Grey-TOPSIS method has been adopted to obtain optimal parametric setting that simultaneously optimizes all the performance measures.