Surface roughness generally depends on the machining process and other factors, such as the friction between the tool and the surface of the part during machining, the plastic deformation of the surface metal when the chips are separated, and the high-frequency vibration in the machining system. The depth, density, shape and texture of marks on the surface of the part also vary depending on the machining technique and the aluminum alloy.
Generally speaking, reducing the surface roughness value will improve the assembly quality of the part, reduce wear and prolong the life of the part, but also increase the processing cost of the part. Therefore, in order to reasonably select the surface roughness value, before processing magnesium-aluminum alloy parts, it is necessary to clarify the role of magnesium-aluminum alloy parts in a specific industry to determine the selection of surface roughness values.
(1) The roughness value of the working surface is less than the roughness value of the non-working surface.
(2) The roughness value of the friction surface is smaller than that of the non-friction surface. The higher the friction speed of the friction surface, the greater the unit pressure, and the higher the stress required for the rolling friction surface is than the required roughness value for the sliding friction surface.
(3) Regarding the clearance fit, the smaller the fitting clearance, the smaller the roughness value; for the interference fit, in order to ensure the firmness and reliability of the fastening strength, the larger the load, the smaller the roughness value required. The roughness value is smaller than that of the interference fit.