What is the material requirement for the processing of precision mechanical parts?

What are the material requirements for machining precision machine parts? Be sure to pay attention to the material density before machining precision machine parts. Once the density is too large, the hardness is also large. Once the hardness exceeds the hardness of the turning tool, it cannot be processed. Not only does it damage parts, it can also be dangerous, such as a sharp knife flying out of the wound. So, what are the requirements for processing materials for precision mechanical parts?