The Sharpening Process of PCD Tools

2021-06-24

One of the purposes of tool sharpening is to obtain cost effective cutting edge quality, and the key to quality is the choice of the size of the sharpening wheel. The finer the particle size of the grinding wheel, the smaller the chipping of the cutting edge and the lower the grinding efficiency. Formulating a reasonable sharpening process according to the specific situation can greatly improve the processing efficiency.

Technic of process

①　The accuracy of the spindle should be good. Generally, the end face of the grinding wheel should be ≤0.02mm. The end face of the grinding wheel jumps too much, the grinding wheel intermittently impacts the cutting edge during grinding, it is easy to cause the cutting edge to chip, and it is difficult to obtain a high-precision cutting edge.

②　The grinding wheel should have a good dynamic balance. The imbalance of the grinding wheel will cause the vibration of the machine tool, which will affect the cutting edge quality and machining accuracy of the processed tool.

③　Ceramic bond diamond grinding wheels should be preferred for sharpening grinding wheels. Because the ceramic bond is prone to microcracks during the grinding process, the abrasive grains are renewed and self-sharpened, so that the grinding process is stable, which is beneficial to improve the accuracy and efficiency of the processed surface. Secondly, a resin bond with higher heat resistance can be selected Diamond grinding wheel.

④　Pay attention to the sharpening of the grinding wheel at the right time, and the size of the sharpening whetstone should be appropriate. When processing PCD tools with diamond grinding wheels, the grinding wheels will be blocked, passivated, high temperature and rapid wear, resulting in reduced processing speed and vibration marks, noise, and burns.

⑤　Because diamond is easy to chemically diffuse with iron-based alloys, which accelerates the wear of the grinding wheel, it is necessary to avoid simultaneous grinding of metal and PCD as much as possible.

⑥　The rotation direction of the grinding wheel must be rotated from the front face of the tool to the flank face. From the force on the cutting edge of the PCD tool during grinding, it can be seen that when the grinding wheel rotates from the rake face of the tool to the flank face, the grinding force acts on the cutting edge inward, that is, the tool is subjected to Compressive stress is not easy to collapse; on the contrary, it is tensile stress, and the cutting edge is easy to collapse. If it is necessary to reverse the sharpening due to the structure of the tool, the resin bond grinding wheel is better than the ceramic and metal bond grinding wheel.

⑦　In order to ensure the quality of the cutting edge and improve the grinding efficiency, the clearance angle of the tool can be divided into a large relief angle and a small relief angle. Use a coarse-grained grinding wheel to first grind the large relief angle, because the contact surface is large and the grinding force is large, and the grinding efficiency is high. Then use a fine-grained grinding wheel to sharpen the small relief angle, the contact surface is small and the sharpening quality is good.