The surface roughness requirements for threads are 3.2 for qualified products and 1.6 for first class and excellent products. The accuracy of labeling on threads, such as M8X1-6h, requires a relatively high surface roughness. The requirements for connecting and fastening threads are relatively low, and generally do not specify tolerances and roughness. They are made with a flat tooth tap. Most threads are not marked with roughness, and if there is a thread marked with roughness, it is generally 3.2. Marked in the upper right corner of the drawing.
Contour arithmetic mean deviation — RaThe arithmetic mean of the absolute value of the contour offset (the distance between a point on the contour line in the Y direction and the reference line) within one sampling length.
Post time: Oct-11-2023