Effect of low cutting speed on ultra-precision cutting of β type titanium alloy with a coated-cemented-carbide tool

In our previous research, coated-cemented-carbide tools were found to be so effective for ultra-precision cutting of titanium metals and stainless steels. The surface roughness formed by ultra-precision cutting of titanium alloys was below 200 nm(Rz) when cutting lengths up to 2,000 m. However it is not adequate for producing efficiently ultra-precision components. It is considered that tool wear is caused by the cutting temperature rise due to the contact of tool to workpiece at high cutting speeds. In order to improve the surface roughness and tool life, in the research, the effect of low cutting speeds on ultra-precision cutting of β type titanium alloy with coated-cemented-carbide tool is examined. Using the extremely low cutting speed, below 1 m/min, the surface roughness at the depth of cut of 5 μm attains 84 nm(Rz) and keeps below 100 nm(Rz) until cutting length of 4,000 m and below 200 nm(Rz) until cutting length of 10,000 m. At the high depth of cut of 500 μm, furthermore, the surface roughness becomes about 100 nm(Rz) at cutting length of 212 m.