For precision machining materials are divided into two categories, metallic materials and non-metallic materials.
For metal materials, the hardness is the largest for stainless steel, followed by cast iron, followed by copper, and finally aluminum.
The processing of ceramics, plastics, etc. is the processing of non-metallic materials.
1, first of all, the requirements of the material hardness, for some occasions, the higher the hardness of the material is the better, just limited to the hardness requirements of the processing machine parts, processing materials can not be too hard, if harder than the machine parts can not be processed.
2, secondly, the material soft and hard moderate, at least one grade lower than the hardness of the machine, but also depends on the role of the processed device is to do what with the machine parts reasonable selection of materials.
In short, precision machining of the material requirements or some, not what material is suitable for processing, such as too soft or too hard material, the former is not necessary for processing, and the latter is not processed.
Therefore, before processing must pay attention to the density of the material, if the density is too large, equivalent to the hardness is also very large, and if the hardness exceeds the hardness of the machine parts (lathe turning tool), it is impossible to process, not only will damage the parts, but also cause danger, such as turning tool flying out of the crash injury. Therefore, in general, for mechanical processing, the material material should be lower than the hardness of the machine tool, so that it can be processed.
