Low Plasticity Burnishing: An Innovative Manufacturing Method for Biomedical Applications

Abstract

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.

Biodegradable Orthopedic Magnesium-Calcium (MgCa) Alloys, Processing, and Corrosion Performance

“…This process, which is developed by Ecoroll, is very similar to the low plasticity burnishing (LPB) process developed by Lambda Technologies in terms of working principal [ 48 ], even though it is claimed that DR produces more cold work than LPB [ 49 ]. Using LPB/DR in medical device manufacturing applications is new and there are only a few published research works for that [ 50 , 51 , 52 ]. Denkena et al [ 12 ] tried to control the corrosion of the Mg-Ca3.0 implant by mechanical treating the implant surface using DR technique and ultimately to achieve adaptable degradation profile for various medical applications.…”

Clinical and radiographic outcomes of total hip replacement with a 3-part metaphyseal osseointegrated titanium alloy stem enhanced with low plasticity burnishing: a mean 5-year follow-up study

“…LPB is a work hardening surface-enhancement method patented by Lambda Technologies (Cincinnati) that produces compressive residual stress to metal subsurfaces and an improved surface finish [24], [34]. Originally used to treat turbine blades in aircraft engines, the process uses cold work hardening to enhance both thermal and biomechanical stability in biomedical devices [24], [35]. LPB was added to the AcuMatch M-series implant (Exactech, Inc., Gainesville) in 2006, and independent fatigue testing has shown a 40% increase in the fatigue strength of the neck segment and an increased implant lifespan by 10-fold [24].…”

Surface treatments for controlling corrosion rate of biodegradable Mg and Mg-based alloy implants

“…It produces cold work hardening and introduces minimal plastic deformation generating compressive residual stress into the subsurface. Low cold working offers both thermal and mechanical stability of the beneficial compression, and the process has recently been used in aerospace and biomedical industries [ 109 , 118 , 119 ]. Similar to low plasticity burnishing, as already indicated, Denkena and Lucas [ 117 ] employed deep rolling to develop adaptable degradation profiles for the purpose of different medical applications of Mg–Ca alloys.…”