An optimization methodology for ultra-precision diamond turning of Ti6Al4V with segment chip formation

Titanium alloys (Ti6Al4V) play an important role in many fields due to their excellent material properties. However, it’s prone to forming serrated chips during ultra-precision machining, which is primarily attributed to their high specific strength and low thermal conductivity. This leads to periodic fluctuations in the cutting force acting on the tool, resulting in tool wear, which affects the surface roughness and causes a deterioration in the quality of the machined surface. In this study, finite element (FE) model is developed to study the serrated chips formation mechanism in diamond cutting of titanium alloys, to build the relationships among cutting parameters, geometry of segment chips and fluctuations of cutting forces. Moreover, the FE model with microstructured surface is proposed to achieve the optimized microstructures array for diamond cutting of titanium alloys. Micro ruling experiments are conducted to verify the developed FE models. Based on the optimization results from diamond cutting of titanium alloys, an optimization methodology is developed to design the microstructures array for diamond turning of titanium alloys with the consideration of cutting parameters, tool path generation and the variations of the local cutting speed. Diamond turning experiment shows that the optimized microstructures array on the machined surface is capable to produce the minimum surface roughness for SPDT of titanium alloys.