The hole measurement of Metal Stamping parts takes the minimum value according to the measurement method of the stop gauge, so when you use the caliper to record the measurement, you can generally record the minimum value (exclude too small values, such as errors caused by measurement errors), (not Excluding special cases) Recording the maximum value and the average value has no practical meaning. The difference in the size of the aperture measured in all directions should be recorded in the roundness of the geometric tolerance, not the aperture.
On the other hand, if it is surveying and mapping and there is no size to refer to, you should decide according to its cross-sectional condition. You cannot just take the average value. For example, the minimum value you measured may be caused by the wear of a punch somewhere. The brightness zone of the section is extremely small, so this minimum value is meaningless.
Generally speaking, the wear of the punch leads to the reduction of the punching hole (specific analysis is required for special-shaped holes), so you can take the maximum value when surveying and mapping. Don’t forget the quality of the section, because the basic size of the aperture is taken when the punch is manufactured. The maximum value within the allowable deviation is multiplied by 0.5 to 0.75 to leave the amount of wear. After a period of use, the punching becomes smaller, but as long as the quality of the section is still acceptable, the value is still within the tolerance range. At this time, the maximum value is Correct. (Similarly, factors such as deformation in the thickness direction of the plate should be excluded, especially for thin plates).
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