Precision machining is a process in which the processing machine changes the dimensions or performance of the workpiece. According to the temperature state of the workpiece being processed, it is divided into cold working and hot working. Generally processed at room temperature, and does not cause changes in the chemical or physical phase of the workpiece, said cold processing. Generally, the processing above or below the normal temperature state will cause changes in the chemical or physical phase of the workpiece, which is called thermal processing.
Cold processing according to the difference between processing methods can be divided into cutting and pressure processing. Heat processing is common in heat treatment, forging, casting and welding.