Investigation of the fake reject cases with unqualified operational dimension based on the error compensation and tolerance compression

Abstract

A fake reject (FR) with unqualified operational dimension often occurs during part machining when the operational data do not coincide with the design data, which can lead to unnecessary waste. We investigated novel judgment and remedial measures for FR to enhance the product qualification rate. We first discuss the reasons for FRs that occur when the calculation for the operational tolerance of the dimension chain is too narrow when calculated using the worst-case scenario method for the process. Following that, we present a novel method for estimating FRs by calculating a new dimension chain. The operational dimension is treated as the concluding link. The actual deviations of the dimensions generated before the operational dimension are used to replace their upper and lower deviations. Finally, based on the error compensation relationship among the component links in the process dimension chain, we propose a novel remedial measure for FR via compressing the dimension tolerance in subsequent processing. We also calculated the dimension tolerance after tolerance compression. This results from this study contribute to the assessment and processing of FRs in part machining.