Application of magnetic field assisted finishing process for nanofinishing of freeform femoral knee joint and performance analysis of finished surface

Abstract

Finishing of femoral knee joint implant is very cumbersome due to its freeform nature. In the present study, a magnetic field-assisted finishing process is employed to uniformly finish the femoral knee implant over its surface curvature at the nanometer level. Experiments are conducted to analyze the freeform surface finishing capability of magnetic field-assisted finishing tool, which proves the tool’s capability to achieve the required surface properties of a femoral knee implant. A comparative analysis between the performance of the magnetic field assisted finishing process and manually polished surface relative to tibial bearing material, that is, ultra-high molecular weight polyethylene with the help of pin-on-disc tribometer, is carried out. It will help to understand the in vivo performance of a finished femoral component of the knee joint by a magnetic field-assisted finishing process. The wear tests prove that the volume loss of the disc material while considering magnetic field-assisted finished pins (11.79 mm3) are better in all cases than the manually polished pins (27.97 mm3). The tribology test also demonstrates that femoral knee implant polished using magnetic field-assisted finishing process will face fewer problems related to wear debris. It will also reduce the problems that occur due to the mixing of debris in the bloodstream. The polishing tool provides almost uniform nanometer-level surface finishing with a standard deviation of 19.23 along the surface curvature. The minimum achieved surface roughness of the femoral knee joint is 20 nm.