Arabian Journal for Science and Engineering https://doi.org/10.1007/s13369-019-03978-5 RESEARCH ARTICLE - MECHANICAL ENGINEERING Inﬂuence of Process Parameters on Machinability of Inconel 718 by Electrochemical Micromachining Process using TOPSIS Technique T. Geethapriyan 1 · T. Muthuramalingam 2 · K. Kalaichelvan 3 Received: 17 September 2018 / Accepted: 15 June 2019 © King Fahd University of Petroleum & Minerals 2019 Abstract Accurate and precise micromachining with intricate features is an essential requirement for various applications of engineering materials in the present scenario. This is effectively achieved by the enhancing the electrochemical machining process, since it is a new and promising technique offering distinct advantages in overall machining quality. The turbine performance depends on a turbine blade and many small apertures with varying diameters of 0.5–4 mm for reducing the heat produced during its operation for improving efﬁciency. The present study was carried out for investigating the effects of diverse input process factors on the machining accuracies in the electrochemical micromachining process under two different electrolytes such as sodium chloride and sodium nitrate. The sodium chloride was found to have a higher material removal rate compared to sodium nitrate as electrolyte. A better surface ﬁnish and radial overcut were achieved with sodium nitrate compared to sodium chloride electrolyte. The optimum combination of ECMM process parameters was determined using TOPSIS method and veriﬁed with a conﬁrmation test. Keywords Inconel 718 · NaCl · NaNO 3 · TOPSIS · Optimization 1 Introduction Electrochemical machining process (ECMM) is a non- traditional machining technique speciﬁcally developed for hard-to-cut materials, such as nickel-based alloys like Inconel, Monel and Hastelloy. It is the suitable option for aerospace, automotive and marine applications. Geethapriyan et al. [1] studied the different process param- eters such as ECMM voltage, concentration of electrolyte, micro-tool feed rate and duty ratio. The complications were analyzed during the investigation to correlate multiple char- acteristics of machining parameters. Alexandre and Atanas [2] studied about the recent developments and innovations in the ﬁeld of electrochemical micromachining and also mon- itored the variable parameters governing electrochemical B T. Muthuramalingam muthu1060@gmail.com 1 Department of Mechanical Engineering, SRM Institute of Science and Technology, Kattankulathur, India 2 Department of Mechatronics Engineering, SRM Institute of Science and Technology, Kattankulathur, India 3 Department of Ceramic Technology, Anna University, A.C.T. Campus, Chennai, India micromachining. It was particularly noted that the usage of sodium chloride increased the current efﬁciency when com- pared to sodium nitrate. Tang and Guo [3] conducted electrochemical machin- ing on special S-03 steel using sodium nitrate and sodium chlorate as electrolyte and studied the microstructure of the machined specimen. It has been observed that the nature of electrolyte can affect the machinability in ECMM process. Asokan et al. [4] investigated the inﬂuence of electrochemi- cal micromachining process on machining of hardened steel using artiﬁcial neural network (ANN) optimization tech- nique. It has been inferred that the adaptation of optimization approach can enhance the machinability in ECMM process. Munda and Bhattacharyya [5] chose the following input parameters to optimize the performance factors pulse-on and pulse-off time ratio, voltage, concentration of electrolyte, fre- quency and tool vibration for machining copper plates in ECMM process using response surface methodology (RSM). The surface performance measures can be analyzed in an efﬁcient way by utilizing a scanning electron microscope (SEM). Kumar et al. [6] cited grey relational analysis (GRA) employed for optimizing the wire-EDM of Inconel X-750 material. However, the selection of the grey coefﬁcient in GRA method is a tedious one. Franci and Joze [7] explained 123