Aims & Objectives: Producing thin-walled rotationally symmetrical parts of difficult-tomachine
materials by electrical discharge machining is an evolving field of research. Poor heat
transmissivity, high hot strength and in-process deflection of thin-walledd Inconel 600 parts pose a
great challenge for its processing by conventional machining methods.
Methods: In this study, a novel hybrid process called Centreless Electric Discharge Grinding
(CEDG) is employed for machining of Inconel 600 tubes using a rotating disc wheel electrode to
improve process parameters. This paper details the experimental findings of the influence of four
process parameters viz. pulse on time, peak current, gap voltage, and duty cycle on the responses
viz. average Material Removal Rate (MRR) and average surface roughness (Ra). Response Surface
Method’s (RSM) central composite design was implemented to determine the effects of parameters
on responses. Analysis of variance (ANOVA) techniques were employed to establish the adequacy
of the mathematical models and to analyze the significance of regression coefficients. RSM’s desirability
approach was used to solve the multi-response optimization.
Results: It was clearly noticed that the peak current and gap voltage were the most influential parameters
to affect the MRR and surface roughness. Maximum average MRR of 473 mg per min.
was achieved at pulse on time 60μs, peak current 25 amps, gap voltage 40 V, at a duty cycle of 8,
while minimum average surface roughness of 8.4 μm Ra was obtained at pulse on time 40μs, peak
current 15 amps, gap voltage 40 V, and duty cycle 6.
Conclusion: Confirmation run was conducted by adjusting the variables at an optimal level within
the selected range. It was concluded that the optimum level of variables can be determined for optimized
responses before conducting the experiment.