Electrochemical Micromachining of Hastelloy C276 by Different Electrolyte Solutions

Micro-electrochemical machining (µECM) is a non-traditional material removal technique developed to cut incredibly hard surfaces which are not easy to cut by any traditional methods. Hastelloy C276 is a nickel-based superalloy, and its applications include equipment components of chemical processing units, food processing units and pharmaceutical industries. Due to the work hardening tendency, machining of Hastelloy C276 by conventional manner becomes exceedingly difficult. µECM can be a possible alternative fabrication technology for machining Hastelloy C276 particularly in micro-domain. This work demonstrates the µECM (micro-hole making) behavior of Hastelloy C276 using NaCl, NaNO3 and hybrid mixture (NaCl + NaNO3 + citric acid) as electrolyte solutions. L9 statistical design of experiments was employed to reduce the number of experiment trials required. Taguchi grey relational approach was executed to determine the most favorable machining variables. Confirmation tests were performed, and the error percentage was calculated. Surface irregularities of the machined parts were systematically examined by 3D surface roughness tester. Experimental results revealed that all the output performances are highly dependent on the type of electrolyte used. Hybrid electrolytic combination produced better material removal rate, lower overcut, lower conicity and most circular holes. Scanning electron microscopy images were used to identify the best-, moderate- and poor-quality micro-holes.