Effect of Ultrasonic Electro-Chemical Polishing Parameters on Surface Roughness and Material Removal Rate of Medical Grade Cobalt Chromium Alloys

The fabrication of prosthesis from superalloys in bio-medical field is a challenging task as a result of strict tolerance requirement in surface finish. Precision surface finish is desired to avoid biocompatibility issue resulting from poor surface finish. Such surface finish requirement can be achieved by using Electro-Chemical Polishing (ECP) process. This research investigated the effect of applying ultrasonic vibration on ECP with process parameters, namely current ( 0.5A-2.5A ) and time ( 2min-10min ) on the surface roughness (Ra) and material removal rate (MRR) of cobalt chromium molybdenum (CoCrMo). The experiments were conducted using ECP and ultrasonic assisted ECP (UECP) processes whereby phosphoric acid (H 3 PO 4 ) and SS 304 steel were used as electrolyte and electrode respectively. The result showed an increasing trend of MRR and Ra as the time and current increased in both processes. It was also found that ultrasonic assisted ECP at current (2.5A) and time (30 min) recorded the highest MRR (0.047 g/min) and the lowest Ra (2.139 µm).