How to Use Your PCD Tool Properly

1. Main performance indexes for PCD cutter

(1) The hardness of PCD cutter can reach 8000hv, which is 80-120 times of cemented carbide;

(2) The thermal conductivity of PCD cutter is 700W / MK, which is 1.5-9 times higher than that of cemented carbide, even higher than that of PCBN and copper;

(3) The friction coefficient of PCD is generally only 0.1-0.3 (the friction coefficient of cemented carbide is 0.4-1), so PCD cutter can significantly reduce the cutting force;

(4) The thermal expansion coefficient of PCD is only 0.9×10^-6~1.18×10^-6, which is only 1/5 of cemented carbide. Therefore, the thermal deformation of PCD cutter is small and the machining accuracy is high;

(5) The affinity between PCD cutter and non-ferrous as well as non-metallic materials is very low, so cutting chips are not prone to adhere to the tool tip and form chip lumps in the process of machining.

2. Choose appropriate grain size for PCD cutter

The selection of PCD grain size is related to the tool processing conditions. For example, when designing cutters for finishing or superfinishing, PCD with high strength, good toughness, good impact resistance and fine grain should be selected. The coarse grain PCD tool can be used for general rough machining. The particle size of PCD material has a significant effect on the wear and breakage performance of cutters.

3. Reasonable selection of PCD tool blade thickness

Generally, the PCD composite sheet is about 0.3-1.0 mm thick, and the PCD composite sheet with cemented carbide layer is about 2-8 mm thick in total. The thin PCD layer facilitates EDM of the blade.

4. Considering the influence of PCD cutting parameters on cutting performance

(1) Cutting speed
PCD tool can cut at very high spindle speed, but the influence of cutting speed on machining quality can not be ignored. Although high speed cutting can improve the machining efficiency, the increase of cutting temperature and cutting force can damage the tool tip and make the machine vibrate. When machining different workpiece materials, the reasonable cutting speed of PCD tool is also different. The appropriate cutting speed varies with different materials processed. For example, the reasonable cutting speed for milling Al2O3 laminate is 110-120m/min; the reasonable cutting speed for turning SiC particle reinforced aluminum matrix composites and silicon oxide based engineering ceramics is 30-40m/min.

(2) Feeding load
If PCD tool is over loaded, the residual geometric area on the workpiece will increase, resulting in the increase of surface roughness; if the feeding load is too small, the cutting temperature will rise and the cutting life will decrease.