ORIGINAL CONTRIBUTION Development and Experimental Study of Electrical Discharge Drilling (EDD) Process for Titanium Alloy Pravendra Kumar 1 • S. K. S. Yadav 1 Received: 6 August 2019 / Accepted: 25 March 2020 Ó The Institution of Engineers (India) 2020 Abstract Advanced engineering materials viz. titanium alloy, nickel alloy, heat-treated steels, superalloy, high- strength temperature-resistant alloys (HSTR) and metal matrix composites (MMCs), etc. are extensively being used in defence, automobile, aerospace, missiles and nuclear applications. Drilling holes in such advanced engineering materials are challenging due to their superior mechanical, electrical and thermal properties. Electrical discharge drilling (EDD) process is a very efficient hybrid machining process (HMP) for making holes in advanced engineering materials irrespective of their hardness and toughness. In the present work, an experimental setup of EDD process has been developed, and the effect of input parameters on the process performance of EDD is studied in terms of output parameters namely material removal rate (MRR) and tool wear rate (TWR). It has been observed from experimental study that the copper tool of 2-mm diameter is suitable for machining of small hole on titanium alloy with minimum TWR. Further, when tool rotation is increased from 600 to 900 rpm, about 17% more MRR and 34% reduction in TWR is observed. Keywords Electrical discharge drilling Á Hybrid machining processes Á Material removal rate Á Tool wear rate Introduction EDM, referred to as electrical discharge machining pro- cess, is one of the most popular advanced machining pro- cesses for conductive materials irrespective of their hardness and toughness. The concept of electrical dis- charge machining (EDM) is first conceived by Joseph Priestley in 1770. B. R. Lazarenko and N. I. Lazarenko observed that metallic materials had been eroded due to electrical sparking in electric circuits. They developed a relaxation circuit by a simple servo controller for main- taining a narrow gap between tool and workpiece. The servo system has led to reduced arcing and converted EDM to a more feasible advanced machining process. Since 1940, die sinker EDM has been reformed by introducing pulse power supply, new techniques of tool and work table movement, CNC programming along with adaptive control systems [1]. In the early stage, EDM was generally used for die making in industries; therefore, it is also known as die-sinking electrical discharge machining, but nowadays, different variants of EDM are in practice such as wire EDM, micro EDM, dry EDM, etc. In die-sinking EDM process, the tool electrode is fed into the workpiece while maintaining a constant gap between the tool (elec- trode) and workpiece. The material is removed as a result of melting and evaporation caused by recurring sparks occurring at regular interval and thereby producing a replica of tool shape in workpiece. In order to make holes in advanced materials using die-sinking operation, hollow tube-shaped electrodes are used in which the dielectric is made to flow down the interior hole of hollow tube for better flushing of debris. But there is a problem of forma- tion of circum-cylinder. A hybrid machining process known as electrical discharge drilling (EDD) is preferred & Pravendra Kumar pravendrahts2012@gmail.com 1 Department of Mechanical Engineering, Harcourt Butler Technical University, Kanpur 208002, Uttar Pradesh, India 123 J. Inst. Eng. India Ser. C https://doi.org/10.1007/s40032-020-00577-4