Magnetorheological finishing of UHMWPE acetabular cup surface and its performance analysis

Abstract

Ultra-high molecular weight polyethylene (UHMWPE) is a highly used polymer in the medical field due to its properties such as good mechanical strength, high hardness, good chemical resistance, and excellent biocompatibility. UHMWPE is used for the manufacturing of acetabular cups in hip-joint implantation. For enhancing the life span and functionality of hip implants, the uniform fine surface finish of the acetabular cup is essential. This is because the non-uniform finish can cause wear and friction during different movements of implants which may lead to osteolysis. In the present work, the UHMWPE acetabular cup surface gets fine finished using the hemispherical tool tip-based magnetorheological (MR) finishing process. To study the efficacy of the tool, magnetostatic finite element analysis is used for analyzing the magnetic field. After the experimentation on 1140 mm2 surface area of the UHMWPE acetabular cup, the surface improvement obtained is 66.67% in 100 minutes of the finishing cycle. For the study of surface morphology, circularity, and microhardness on the finished UHMWPE acetabular cup surface, the scanning electron microscopy, co-ordinate measuring machine, and microhardness tester machine are used. Results show that the present process is suitable for the uniform fine finishing of the UHMWPE acetabular cup with improved surface characteristics.