Enhancing machining rate and geometrical accuracy in electrochemical micromachining of Co-Ni-Cr-W superalloy

ABSTRACT

Electrochemical micromachining (EMM) process is a contactless versatile electroforming process, used to fabricate highly precise micro-features and complex contours with the desired surface finish. In this research work, a fabricated-tapered hollow tool (THT) close to Ø0.3 mm is fabricated adopting reverse potential drop off approach and compared against the standard cylindrical hollow tool (CHT) of Ø0.3 mm for EMM which is aimed to enhance MRR, geometrical accuracy by reducing the overcut and the surface finish. The tools are then used in EMM setup to machine Co-Ni-Cr-W-based superalloy for the first time, considering the most predominant process factors including Voltage (V), Duty ratio (%), Feed rate (mm/min) and electrolyte concentration (gl⁻¹). Taguchi’s design of experiment having 2 × L9 OA’s is used in this study. ANOVA was used to statistically analyze the most significant parameter and to study its influence over the output responses. The desirability function-based optimization suggests that the experimental run #9 has the desired optimal parametric combination resulting in increased MRR by 2.04%, 24.57% reduction in overcut, and with reduced surface roughness while using THT when compared to the CHT. EBSD, EDS, SEM, VMS, and non-contact surface tester were inured with to examine surface morphology of electrodes.

KEYWORDS:

• Electrochemical
• micromachining
• reverse
• potential
• taper tool
• Haynes 188
• alloy

Acknowledgments

The author acknowledges the machining facility provided by the Department of Manufacturing Engineering, College of Engineering Guindy, Anna University, Chennai and also thank Mr. Aseem Suri, CEO of Sinergy Nanosystems, Pune for his valuable support.