Low Plasticity Burnishing: An Innovative Manufacturing Method for Biomedical Applications

Biomedical manufacturing technologies are assuming highly visible position at the frontiers of manufacturing. A new field, “engineered surfaces,” is emerging as a more effective and economic route to successful manufacture. Low plasticity burnishing (LPB) is relatively a new method of surface enhancement, which raises the burnishing to the next level of sophistication. LPB can provide deep and stable surface compression for improved surface integrity characteristics. This technology could be applied to diversified biomedical applications, since it has the potential to improve many surface characteristics, such as low- and high-cycle fatigue strengths, surface finish, surface hardness, corrosion resistance, wear resistance, etc. The present study focuses on the surface roughness, microhardness, surface integrity, and fatigue life aspects of AISI 316L work material, which is most commonly used in prosthesis, using full factorial design of experiments. Favorable and optimum conditions could be predicted and tailored for different biomedical requirements and applications. The assessment of the surface integrity aspects on work material was done, in terms of identifying the predominant factors, their order of significance, evaluating the interaction effects of parameters, and setting the levels of the factors for minimizing surface roughness and∕or maximizing surface hardness and fatigue life. Regression models were developed for surface characteristics of importance as response variables. Subsurface microhardness studies were also done to assess the depth of compression, altered material zone, and correlate fatigue life with surface roughness and surface hardness. The process can be applied to critical components used in biomedical field, such as total hip prosthesis, invasive surgeries, or medical implants effectively, as the LPB process today has significant process cycle time advantages, lower capital cost, and adaptability to conventional machine shop environment.