Among various geometric measurements,dimension measurement is the most fundamental. Due to the different shapes,sizes, precision requirements, and usage scenarios of the tested parts, themeasuring instruments used are also different. For large-scale productionworkshops, in order to improve measurement efficiency, gauges were often usedfor inspection in the past, but now fully automatic 3D optical coordinatemeasuring equipment can be used for rapid detection;

The acceptance principle stipulated bynational standards is that the acceptance method used should only allow forincorrect waste fabric to be accepted. In order to ensure this acceptanceprinciple, ensure that the parts meet the interchangeability requirements, andminimize false acceptance, acceptance limits have been established. Theacceptance limit refers to the size limit used to determine whether a workpieceis qualified or not when inspecting its dimensions. Determine according to thefollowing two methods:

1. When determining the acceptance limit,move the maximum and minimum limit dimensions marked on the drawing within thetolerance zone of the workpiece by one safety margin A, that is

Upper acceptance limit=maximum limitdimension - A

Lower acceptance limit=maximum limit size+A

2. In the above formula, A is zero, whichmeans that the upper and lower acceptance limits are equal to the maximum andminimum limit dimensions on the drawing, respectively;

Among them, A can ensure the quality andinterchangeability of the parts, preventing them from being mistakenlyreceived. Generally, A is 1/10 of the workpiece tolerance. In actualproduction, it is not possible to produce according to the original limitdimensions, and production should be carried out within the range determined bythe acceptance limit. Therefore, this range becomes the production tolerance.