表面粗糙度与零件的尺寸精度间虽没一个函数关系,如手柄、镜面,它们的尺寸精度不高,但表面质量要求较高。而轴颈与轴承的配合,不仅形状精度要求高,表面质量也要求较高。为了便于将常用机械图样中的光洁度转换为表面粗糙度,现将轮廓算术平均偏差值Ra与旧标准表面光洁度对照列表如下。表中有三个方案,第一 Although there is no functional relationship between the surface roughness and the dimensional accuracy of parts, such as handle and mirror, their dimensional accuracy is not high, but the surface quality is higher. The journal and the bearing, not only the shape of high precision, the surface quality is also demanding. In order to facilitate the conversion from the finish of the common mechanical drawing to the surface roughness, the outline arithmetic mean deviation value Ra is compared with the old standard surface finish as follows. There are three options in the table, first