How surface roughness is controlled in precision hardware machining

With the progress of science and technology and the development of society, people have put forward higher and higher requirements for the performance and quality of precision machined products. The performance and quality of the product is determined by the product design and is guaranteed by the quality of the manufacturing and assembly of precision hardware machining, which includes both machining accuracy and surface quality. The surface quality of precision mechanical parts is one of the most important indicators, especially for the reliability of the parts at high speed, high temperature and high pressure conditions has a great impact.

Machining surface is through precision machining or other methods to change the size, shape and performance of the blank surface, so that it meets the requirements of the design drawings. But the external surface formed by precision machining of mechanical parts after turning is not a completely ideal surface. After machining a very thin surface layer is formed on the surface of the part, whose characteristics are very different from those of the internal substrate.

Precision hardware processing, the surface in the entire cutting process in the wedge, extrusion, fracture and friction of the complex state of force, elastic and plastic deformation, in the cutting force, cutting heat and the common action of the surrounding media, changing the original geometric characteristics of the workpiece surface and physical and mechanical properties. Therefore, the use of "surface quality" to evaluate the geometric, physical, chemical or other engineering properties of the surface layer of the machined parts and the degree of compliance with the technical requirements of the parts, the main content of the expression is divided into the following aspects.

Surface roughness: precision hardware processing surface with a small spacing of the peaks and valleys of the microscopic geometry of the characteristics, it is mainly precision machining in the cutting tool trajectory formed by the wave height and wavelength of the ratio is generally greater than 1:50.

Surface processing texture: the main direction of the surface microstructure, it depends on the surface formation of the precision machining method used, that is, the relationship between the main motion and the feed motion.

Surface waviness: an intermediate geometry error between macro geometry error and surface roughness, it is mainly caused by the offset and vibration of the cutting tool and its ratio of wave height to wavelength is generally 1:50 to 1:1000.

Physical and mechanical properties of the surface layer: during the machining of precision mechanical parts, various complex physical and chemical changes occur on the surface of the part, causing changes in the physical and mechanical properties of the surface layer.

The surface quality reflects some geometrical characteristics and the physical and mechanical properties of the surface layer. It has a great influence on the wear resistance, fit quality, fatigue strength, corrosion resistance and contact stiffness of precision hardware processing and other aspects of the use of performance. The service life of precision hardware depends to a large extent on the wear resistance of the parts, the wear resistance of the parts and the friction of the material, the working environment lubrication conditions and the surface quality of the parts and other factors, in other conditions to determine the case, the surface quality of the parts plays a very important role.