Advanced ceramics have different post-processing methods according to different performance requirements, including mechanical machining, electrical processing, ultrasonic processing, laser processing, and composite processing. The article will briefly state the mainstream types of ceramic machining technology.
1) Precision Turning
Turning mainly uses high hardness and super wear-resistant diamond tools to cut ceramic materials. Polycrystalline diamond tools find it difficult to produce smooth cutting edges and are generally only used for rough machining. Natural single-crystal diamond tools are used for the fine-tuning of ceramic materials, and micro-cutting is conducted in the processing. Due to the high hardness and brittleness of ceramic materials, it is difficult to ensure the accuracy of turning processing, so turning processing has been not widely used, and it is still in the R&D stage.
2) Precision Grinding
Grinding is currently widely used in machining processing. The grinding wheel is regularly a diamond grinding wheel. Different scholars have different explanations for the grinding mechanism of diamond grinding wheels. Still, in general, the common point is that brittle fracture is the main reason for the formation of material removal. In the grinding process, the removal of chips is a major problem, and cooling fluid is generally used for cleaning. The coolant not only plays the role of flushing the chip powder but also can reduce the temperature of the grinding area, improve the grinding quality, and reduce the thermal decomposition of the binder around the abrasive particles. Grinding fluids are generally selected with good cleaning performance and low viscosity. Diamond grinding wheels have different grinding characteristics due to varying types of binders and abrasive particle concentrations. The size of diamond particles is another main factor affecting ceramic workpieces' surface quality. The larger the particles, the greater the surface roughness, but the higher the processing efficiency.
3) Precision Drilling
Ceramic materials are mostly drilled with a trepanning drill. The structure of the trepanning drill is that an annular diamond grinding wheel is welded to a hollow steel pipe, and the welding process is silver welding. When drilling ceramic materials, the diamond grinding wheel rotates at high speed and uses the diamond abrasive grains on the end face to cut the material.
4) Lapping and Polishing
In some areas of industrial production, grinding alone cannot meet the surface finish requirements of ceramic parts, which is why lapping and polishing are usually conducted after machining. On the other hand, ceramic materials are less ductile and brittle, and their strength is easily affected by surface cracks. If the machined surface is rougher and the surface cracks are more significant, it is easier to produce stress concentration, resulting in lower strength of the workpiece. Therefore, lapping is not only to achieve a designated roughness and high dimensional & shape accuracy but also to improve the strength of the workpiece. Polishing is a finishing process that uses a soft polisher and fine-grained abrasives to act on the workpiece at low pressure.