Diamond Tool Life in SPDT of Polycarbonate

Plastics are very common materials that can be diamond turned and widely used in optics and our ultra precise applications.Surface texture parameters (roughness and waviness) are very important considerations in these applications. An attempt is done to analyze the diamond tool life phases and its wear characteristics during single point diamond turning of polycarbonate (plastic) and to optimize various machining parameters such as tool feed rate, depth of cut and spindle speed for surface texture quality. Experiments showed that there was no crator wear, but very small amount of flank wear was observed after machining about 7Kms. As further machining is done, tool tip started getting flat from cutting point, thus increasing the Surface roughness value. So surface roughness value (70nm) was kept as criteria for tool failure. So tool was failed after machining for about 200Kms.As polycarbonate is plastic, linear trend is seen in both roughness and waviness. Further observation was that surface roughness value decreases for spindle speed up to certain limit and then started increasing. For depth of cut, surface roughness value increases for certain value and then decreases.