Cold working, usually refers to the metal cutting processing, that is, using cutting tools to remove the excess metal layer from the metal material (blank) or workpiece, so that the workpiece to obtain a certain shape, dimensional accuracy and surface roughness processing methods. Such as turning, drilling, milling, planing, grinding, broaching, etc. In metal technology, as opposed to hot working, cold working refers to the processing of plastic deformation of metals at temperatures lower than the recrystallization temperature, such as cold rolling, cold drawing, cold forging, stamping, cold extrusion, etc.. Cold working deformation resistance, in the metal forming at the same time, the use of hardening to improve the hardness and strength of the workpiece. Cold working is suitable for processing small cross-sectional size, processing size and surface roughness requirements of metal parts. For example 1000 series cold-worked aluminum sheet.
Hot working, in conditions higher than the recrystallization temperature of the metal material at the same time to produce plastic deformation and recrystallization of processing methods. Thermal processing usually includes casting, hot tying, forging and metal heat treatment processes, and sometimes welding, thermal cutting, thermal spraying and other processes are included. Thermal processing can make metal parts in the formation of the same time to improve its organization, or the formed parts to change the crystalline state to improve the mechanical properties of the parts. For low melting point of metal materials, such as lead, zinc, tin, etc., its recrystallization temperature is low, the plastic processing of them at room temperature, also belongs to thermal processing.