Hardware processing surface is to modify the size, appearance and characteristics of the rough surface through precision machining or other methods to make it meet the requirements of the design sample. However, the inner hole surface formed after milling of precision mechanical parts is not a completely ideal surface. After processing, a very thin outer layer is formed on the surface of the part, and its characteristics are very different from those of the internal base material.
During the precision metal processing, the surface is under the complex stress of wedging, extrusion, fracture and friction during the whole drilling process, and the ductility and plastic deformation are terminated. Under the combined effect of cutting speed, drilling heat and surrounding materials, the original geometric characteristics and physical properties of the workpiece surface are modified. Therefore, "surface quality" is used to evaluate the geometric, physical, chemical or other engineering characteristics of the surface of the processed parts and the degree of compliance with the technical requirements of the parts. The specific contents described are divided into the following aspects.
1. Surface roughness: The external geometrical features formed by the small-spaced peaks on the surface of precision metal processing. It is mainly composed of the trajectory of the cutting tool in precision machining, and the ratio of its wave height to the wavelength is generally more than 1:50.
2. Surface waviness: The intermediate geometrical deviation between the macroscopic geometrical deviation and the surface roughness. It is mainly caused by the deviation and vibration of the cutting tool. The ratio of its wave height to the wavelength is generally 1:50 to 1:1000.
3. Surface texture: The key aspect of the surface external economic structure, which depends on the precision machining method selected for surface formation, that is, the relationship between the main motion and the tool movement.
4. Scars: Defects on some parts of the surface of precision metal processing, most of which are randomly distributed. For example, burrs, cracks and scratches.
5. Physical and mechanical properties of the surface layer: In the production process of precision mechanical parts, various complex physical changes occur on the surface of the parts, causing changes in the physical properties of the surface layer.
