Verification of residual stress induced by the centre-hole-drilling method when applied to ASTM F-75 (CoCr alloy)

ASTM F-75 is a standardised material for implant use and is widely used for components which have moving-contact surfaces, i.e. femorals. ASTM F-75 (CoCr) prosthetic knee implants, specifically femoral components, distort inconsistently as a result of redistributed Residual Stress (RS) during grinding. Centre-Hole-Drilling (CHD) has been applied to ASTM F-75 femorals, but problems occurred with the drill stalling and poor geometry holes. A technique applied by Veqter, utilising a dental burr and spindle speeds in the region of 10k rpm driven by an electric motor, proved successful in inducing a square edge, flat bottom hole. But it is currently unknown what level of stress is induced by this drilling method. It is proposed to perform ND experimentation on samples with stress relieved by annealing and uniform plastic deformation, to compare with and verify CHD results.