Precision parts processing is not all materials can be precisely processed, some materials are too hard, exceeding the hardness of the processing machine parts, it may break down the machine parts, so these materials are not suitable for precision mechanical processing, unless it is made of special materials, or laser cutting. For precision parts processing materials are divided into two categories, metal materials and non-metal materials. Generally speaking, the hardness of metal materials is stainless steel, followed by cast iron, followed by copper, and finally aluminum. The processing of ceramics and plastics belongs to the processing of non-metallic materials. 1. Firstly, it is the requirement of material hardness. For some occasions, the higher the hardness, the better. It is only limited to the hardness requirement of the machined parts. The machined materials can not be too hard. If they are harder than the machined parts, they will be unable to be machined. 2. Secondly, the material is moderate in hardness and softness, at least one grade lower than the hardness of the machine parts. At the same time, it depends on what the function of the processed devices is and the reasonable selection of the machine parts. In a word, there are still some requirements for material quality in precision machining, not all materials are suitable for processing, such as soft or hard materials, the former is not necessary for processing, and the latter is unable to process. Therefore, the most basic one is to pay attention to the density of the material before processing. If the density is too high, the hardness is also very large. If the hardness exceeds the hardness of the machine parts (lathe tool), it will be impossible to process. It will not only damage the parts, but also cause danger, such as the tool flying out and injuring people. Therefore, generally speaking, for mechanical processing, the material quality is lower than the hardness of the machine tool, so that it can be processed.