Machinability of Silicon and German Silver in Micro Electrical Discharge Machining: a Comparative Study
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ORIGINAL PAPER
Machinability of Silicon and German Silver in Micro Electrical Discharge Machining: a Comparative Study Sushmita Deka 1 & Siddhartha Kar 1 & Promod Kumar Patowari 1 Received: 5 December 2019 / Accepted: 22 April 2020 # Springer Nature B.V. 2020
Abstract This paper introduces an experimental investigation of micro hole drilling on two different categories of material such as silicon and german silver using micro electrical discharge machining (μEDM) process. The conductivities of the two materials are of different levels; silicon being a semiconductor has relatively much lower electrical conductivity as compared to german silver which is an alloy of copper, nickel and zinc. The tool electrode used is tungsten rod of 518 μm diameter. Responses like material removal rate (MRR), taper angle (TA), circularity error (CE) and overcut (OC) have been calculated and their variation with respect to the process parameters such as capacitance and voltage are evaluated. In both the materials, the values of all the responses increases with an increase in both voltage and capacitance. German silver is observed to have a higher MRR and OC than that of silicon while silicon has a higher TA for the same values of process parameters. The CE of silicon is higher at lower capacitance while it is higher for german silver at higher capacitance. From the analysis of variance (ANOVA), it is observed that both the voltage and capacitance played a significant role in all the responses. An optimum condition of micro hole drilling of both the materials is achieved by formulating overall evaluation criteria (OEC), which combines all the response parameters into a single index. In most of the cases, OEC of german silver is found to be higher than silicon, thus justifying the superior machinability performance of german silver. From the ANOVA of OEC, the role of capacitance is found to be more significant as compared to the voltage. Keywords Micro EDM . Drilling . Micromachining . Semiconductor . Silicon . German silver . Overall evaluation criteria . OEC
1 Introduction Electrical discharge machining (EDM) is an electro-thermal process which removes material by melting and vaporization due to the intense heat produced by the occurrence of spark between the workpiece and tool. Melting and vaporization occur at the smallest inter-electrode gap between the workpiece and tool surface due to attainment of high temperature by the occurrence of electric discharges [1]. The basic advantage of EDM is its ability to machine any electrically conductive material with high precision and low manufacturing cost [2, 3]. There are various uses of EDM in the practical field like manufacturing of cooling holes in land turbines, fabrication of die/mold, machining hard and tough metals used in aerospace
* Promod Kumar Patowari [email protected] 1
Department of Mechanical Engineering, National Institute of Technology Silchar, Silchar, Assam 788010, India
and automotive industries, surgical applications, etc. [4, 5]. Micro electrical discharge mac
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