Areas near the specification limits where conformance or non conformance cannot clearly be determined because of the measurement Uncertainty ranges (Figure 1). When the measurement result Y (measured quantity value yi as sociated with the expanded measurement uncertainty UMP) includes one of the specification limits, neither conformance or non-conformance can be proved (Figure4).
Note 1: Uncertainty ranges are symmetrical to the specification limits.
Note 2: As a result, work pieces can neither be automatically accepted nor rejected. For such “dead end cases”, it is advisable to follow the rule below:
Reduce the uncertainty of measurement and thereby reduce the uncertainty range in order that conformance or non-conformance can clearly be demonstrated.
Mutual agreement between customers and manufacturers:
reference:VDA
