Rejection of articles in selective assembly owing to measurement errors

Conclusions

A precise (2) and approximate (6) expressions are provided for determining rejected articles as the result of allocating incorrectly-measured components to inappropriate groups. One of the reasons which impeded the application of selective assembly was the assumed requirement for high-precision measuring instruments. This is so, if the absolute values of measurement errors are considered, since tolerances for dimensions in selective groups in certain assembly processes amount to microns, or even their fractions. However, it has been shown in this article that a very large error with respect to the group tolerance can be admitted. For instance, when the two quantities are equal, the rejected articles amount only to 2.8% of the total. The relationships (2) and (6) provided above can also be used for assembling according to the complete interchangeability method.