Surface roughness of machined mechanical parts is an important technical indicator reflecting the micro-geometric error of machined surface layer of mechanical parts, is the main basis for testing the quality of the surface layer of the parts, directly related to the quality of goods, service life, product cost. The methods of selecting the surface roughness of mechanical parts are calculation methods, testing methods and analogous ways.
A common application in the machining design of mechanical parts is the analogical approach, which is simple, fast and reasonable. The application requires adequate references and a wide range of materials and references are given in various current mechanical construction design guides. Commonly, surface roughness is compatible with dimensional tolerance levels. In general, the smaller the standard tolerances specified for machining and production of mechanical parts, the smaller the value of surface roughness of mechanical parts, but there is no fixed functional relationship between them.
Mechanical parts machining strength is the ability of the part not to break or undergo more than the allowed plastic deformation during work, and is the most basic provision for all normal operation and production safety of the equipment. Standard countermeasures to improve the strength of the parts are: in order to expand the specifications of the risky cross-section of the parts, expand the moment of inertia of the cross-section, effectively design the case of the cross-section; the use of high-strength raw materials, the raw materials to expand the heat treatment process to improve the strength and reduce the thermal stress, operation manufacturing process to reduce or eliminate microscopic shortcomings, etc.; in order to reduce the load of the parts to reduce the stress level, etc., the structure of the parts should be properly involved.