In the machining process, it is often encountered that the dimension of machining accuracy is not marked. Generally, customers will describe the reference standard with text on the drawing. Of course, each country and region has its own standard, but the common standards are as follows:

The first is according to the international standard. The following is the standard tolerance table of 0-500mm basic dimension with accuracy level 4 to 18:

According to the international standard, the second one is suitable for metal cutting and general stamping processing

Linear dimension: outer dimension, inner dimension, step size, diameter, radius, distance, etc

Angle dimension: a dimension that does not usually indicate an angle value, for example, a right angle of 90 degrees

Shape tolerance refers to the total variation allowed by the shape of a single actual feature, which is expressed by shape tolerance zone, which includes four elements of tolerance shape, direction, position and size; shape tolerance items include straightness, flatness, roundness, cylindricity, profile of line, profile of flat wheel set, etc.

Position tolerance includes orientation tolerance, positioning tolerance and runout tolerance. See the table below for details: