The influence of deep cryogenic treatment and in-situ cryogenic micro turning of Ti-6Al-4V on cutting forces, surface integrity and chip morphology

摘要

The demand for sustainable manufacturing of axi-symmetric, micro turned titanium based neurosurgical implants are increasing. However, dry micro-turning of titanium alloy at higher cutting speeds, results in poor surface integrity, because of continuous saw-tooth chip formation, chip adhesion, and micro-scratch initiation on the machined surface. To overcome these issues in micro-turning, two techniques were attempted in this paper. First, Ti-6Al-4V is cryogenically cooled for 72 hours and then subsequently heat treated for four hours at 170°C before machining. Second, in-situ cryogenic experiments, liquid nitrogen is fed in the cutting zone. It is observed that, in-situ cryogenic micro-turning assists in ease of chip fracture resulting in good surface finish. It inhibits the formation of saw-tooth chip and thereby a fluctuation of forces with time is limited. Micro-scratch and adhesion of machined chips were present in non-treated and deep-cryogenic treated surfaces whereas, in-situ cryogenically micro-turned surfaces were free from the above defects.