Precision machining is a process that alters the shape, size, or performance of workpieces using machine tools. Depending on the temperature state of the workpiece being processed, it is divided into cold working and hot working. Generally, cold working is performed at room temperature and does not cause chemical or phase changes in the workpiece. Hot working, typically done at temperatures above or below room temperature, induces chemical or phase changes in the workpiece. Cold working can be further categorized into cutting and forging processes. Hot working commonly includes heat treatment, forging, casting, and welding.