Optimization of process parameters in ECDM machining using Taguchi based grey relation analysis

Abstract

Electrochemical discharge machining (ECDM) is a hybrid machining process capable of micromachining conductive and nonconductive materials. The recent development and application of nonconductive materials, such as glass, composites, and ceramics in MEMS and microfluidic devices, have emphasized studying the ECDM process for micro holes and channel formation. The current study uses Taguchi's L27 orthogonal array to design the experiments, evaluate responses by the signal-to-noise ratio, analyze the variance of process parameters (ANOVA), and predict optimal settings for a multi-objective response using grey relation analysis (GRA). The experiments were conducted using two tools, a bare copper tool and Nickel coated copper tool, over a glass substrate. The machining process's output characteristics (radial overcut, heat-affected zone, and hole circularity) were studied by varying input parameters such as applied voltage, tool feed rate, and machining time. The experimental results revealed that Nickel coated Cu tool reduces the average hole overcut and heat-affected zone width and increases the overall circularity of the hole as compared to the bare Cu tool. Based on grey relational grade analysis, the optimal parameters were identified: the applied voltage of 36 V, tool feed rate of 110 µm/min, and one-minute machining time with Nickel coated copper tool. In contrast, a bare copper tool electrode provides optimal process parameters as an applied voltage of 36 V, 110 µm/min tool feed, and a machining time of two minutes for drilling holes in borosilicate glass.