Precision machining refers to the technology of changing the shape, size, or properties of a workpiece through machining. Based on the temperature state of the workpiece during machining, it can be divided into cold working and hot working. Cold working is performed at room temperature and does not cause chemical or phase changes in the workpiece; it includes cutting and pressure processing. Hot working induces phase changes in the material through temperature changes and encompasses casting, forging, welding, and heat treatment.
Precision and ultra-precision machining are usually classified according to machining accuracy. Machining can be divided into three stages: general machining, precision machining, and ultra-precision machining. Currently, precision machining refers to machining technology with a machining accuracy of 1~0.1µm and a surface roughness of Ra0.1~0.01µm, but this boundary is constantly changing with technological advancements. Ultra-precision machining is a process that uses strictly constrained relative motion between a part and a cutting tool on ultra-precision machine tools to perform micro-cutting of materials, achieving extremely high shape accuracy and surface finish. Current ultra-precision machining refers to machining technologies where the dimensional accuracy of the machined parts is higher than 0.1 μm, the surface roughness Ra is less than 0.025 μm, and the positioning accuracy and repeatability of the machine tool are higher than 0.01 μm. It is also known as sub-micron level machining technology and is developing towards nanoscale machining technology. Ultra-precision machining includes micro-machining, ultra-micro-machining, finishing, and finishing techniques. Traditional precision machining methods include cloth wheel polishing, belt grinding, ultra-fine cutting, fine grinding, honing, lapping, ultra-precision polishing, and magnetic particle finishing. Ultra-precision machining techniques include ultra-precision cutting, ultra-precision grinding, ultra-precision lapping, and ultra-precision special machining.
