When designing the finished part, the most common choice for the selection of the surface roughness value of the cutting machine is the analogy method. This method is simple, rapid and economical, and can meet the requirements of the use of parts and the general principle of selection. For specific selection, you can refer to the following principles.
(1) General principle: Under the premise of ensuring the functional requirements of the surface of the part, try to select a larger surface roughness parameter value.
(2) In the same part J:, r: the surface roughness parameter of the cutting machine should be hlk working surface is small.
(3) The friction surface has a smaller value of the roughness parameter than the non-detection surface. If the frictional speed of the friction surface is higher, the larger the unit music force is, the value of the rent roughness parameter is more than that of the south; the rolling friction surface is smaller than the sliding friction surface.
(4) When the gap is matched, the smaller the matching clearance, the smaller the rent roughness parameter should be, and the interference fit. To ensure the connection strength is firm and reliable. The larger the load, the smaller the roughness parameter value is required. In general, the clearance fit ratio is smaller than the interference fit roughness parameter value.
(5) The roughness parameter value of the mating surface should be equivalent to the dimensional accuracy requirements. When the semi-cooperating properties are the same, the smaller the part size, the smaller the value of the corresponding rent roughness parameter; the accuracy level. The small size has a smaller roughness parameter value than the large size. The axis has a smaller roughness parameter value than the hole (especially the accuracy of I D8).
(6) The surface of the periodic load and the fillet where the stress mart may occur, and the roughness dimension value of the groove should be small.
(7) The anti-corrosion and sealing requirements are high, and the wavefront with aesthetic appearance requirements should use a smaller roughness height parameter value.