Influence of cutting parameters on surface roughness and strain hardening during milling NiTi shape memory alloy

Abstract

Nitinol is well known as one difficult-to-machine alloy due to its poor machinability, which requires a large amount of cutting force and cutting temperature, resulting in poor surface roughness and strain hardening. The influence of the milling parameters on the surface roughness and strain hardening with orthogonal experiment is studied in this paper. It is found that cutting speed and feed rate have important influence on the surface roughness and strain hardening. When the cutting speed becomes larger, the surface roughness decreases, while the work hardening decreases first and then gets bigger. The surface roughness and work hardening increase gradually when the feed rate increases. However, the width of cut has little effect on the above surface roughness and strain hardening. The research shows that the medium range of cutting speed selection is better for the milling of NiTi shape memory alloy as used as medical implant materials that can achieve the minimal work hardening and smaller surface roughness.