Effect of mechanical tumbling parameters on surface roughness and edge radius of medical grade cobalt chromium alloy

Abstract

Smoothly polished prosthesis surface is a crucial requirement in medical application and important feature that determine the proper response to corrosion and biocompatibility in the human body. Tumbling is one of the pre-polishing processes that can be conducted in order to improve the surface roughness of the machined prosthesis. However, the using of ceramic media for the tumbling process in medical application is not widely reported. This study was conducted to investigate the effect of mechanical tumbling parameters on the surface roughness of medical grade CoCr alloy by using alumina (Al2O3) based ceramic media. The experiment was performed with a different level of rotational speed (35, 55, and 75 rpm) and soaking time (4, 6 and 8 hours) of the tumbling process. The surface roughness of specimens before and after the process was measured using Mitutoyo Formtracer CS- 5000 and the edge radius was measured using Olympus SZX9 microscope integrated with I-solution Lite software. It was figured that 6 hours tumbling time at 55 rpm showed the most significant reduction (32 %) in surface roughness (Ra) of the CoCr alloy specimen, while 8 hours tumbling time at 75 rpm showed the highest effect on the edge radius of the specimen at 63 % increment.