Now showing 1 - 3 of 3
  • Publication
    Prediction of tool-wear in turning of medical grade cobalt chromium molybdenum alloy (ASTM F75) using non-parametric Bayesian models
    We present a novel approach to estimating the effect of control parameters on tool wear rates and related changes in the three force components in turning of medical grade Co-Cr-Mo (ASTM F75) alloy. Co-Cr-Mo is known to be a difficult to cut material which, due to a combination of mechanical and physical properties, is used for the critical structural components of implantable medical prosthetics. We run a designed experiment which enables us to estimate tool wear from feed rate and cutting speed, and constrain them using a Bayesian hierarchical Gaussian Process model which enables prediction of tool wear rates for untried experimental settings. However, the predicted tool wear rates are non-linear and, using our models, we can identify experimental settings which optimise the life of the tool. This approach has potential in the future for realtime application of data analytics to machining processes.
      370Scopus© Citations 15
  • Publication
    An Investigation of Force Components in Orthogonal Cutting of Medical Grade Cobalt Chromium Alloy (ASTM F1537)
    An aging population, increased physical activity and obesity, are identified as life style changes contributing to growth in the use of in-vivo prosthetics for total hip and knee arthroplasty. Cobalt chromium alloys, due to mechanical properties and excellent biocompatibility, uniquely qualify as a class of materials that meet the stringent functional requirements for these devices. To cost effectively assure the required dimensional and geometric tolerances, manufacturers invariably rely on high precision machining. However, a comprehensive literature review has shown that there has been limited research into mechanical cutting of these materials. This paper delineates the physical and mechanical properties that determine the machinability of a material, and compares medical grade cobalt chromium alloy ASTM F1537 with titanium alloy, Ti-6Al-4V ASTM F136. The results of a full factorial orthogonal cutting experiment are reported where cutting and thrust force components were measured over a range of cutting speeds (Vc) and levels of undeformed chip thickness (hm). It was found that the forces generated in cutting of ASTM F1537 are significantly higher than for ASTM F136, depending primarily on undeformed chip thickness, but with some influence of the cutting speed. The effect of chip segmentation on component force variations is also reported.
      871Scopus© Citations 7
  • Publication
    Prediction of tool-wear in turning of medical grade cobalt chromium molybdenum alloy (ASTM F75) using non-parametric Bayesian models
    We present a novel approach to estimating the effect of control parameters on tool wear rates and related changes in the three force components in turning of medical grade Co-Cr-Mo (ASTM F75) alloy. Co-Cr-Mo is known to be a difficult to cut material which, due to a combination of mechanical and physical properties,is used for the critical structural components of implantable medical prosthetics. We run a designed experiment which enables us to estimate tool wear from feed rate and cutting speed, and constrain them using a Bayesian hierarchical Gaussian Process model which enables prediction of tool wear rates for untried experimental settings. The predicted tool wear rates are non-linear and, using our models,we can identify experimental settings which optimise the life of the tool. This approach has potential in the future for real time application of data analytics to machining processes.
    Scopus© Citations 15  263