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Part 1 of ISO/TS 14253 establishes the rules for determining when the characteristics of a specific work piece or measuring equipment are in conformance or non-conformance with a given tolerance (for a work piece) or limits of maximum permissible errors (for measuring equipment), taking into account the uncertainty of measurement.
It also gives rules on how to deal with cases where a clear decision(conformance or non-conformance with specification) cannot be taken, i.e. when the measurement result falls within the uncertainty range (see Figure below) that exists around the tolerance limits.
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Conformance
Fulfilment of specified requirements.
Conformance zone
Specification zone reduced by the expanded uncertainty of measurement UMP (Figure below).
Note: The specification is reduced by the expanded uncertainty of measurement UMP at the upper and lower specification limits. In case of characteristics with a one-sided specification, this reduction does not apply to the natural boundary side.
Proof of conformance
If the measurement result Y (measured quantity value yi associated with the expanded measurement uncertainty UMP) is lying within the specification zone, the conformance with the tolerance is proved and the product can be accepted.
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Non-conformance
Non-fulfilment of a specified requirement.
Non-conformance zone
one(s) outside the specification zone extended by the expanded uncertainy of measurement UMP (Figure 1).
Note: The specification is extended by the expanded uncertainty of measurement UMP at the upper and lower specification limit. In case of characteristics with a one-sided specification, this reduction does not apply to the natural boundary side.
Proof of non-conformance
Non-conformance with the tolerance is proved when the measurement result Y (measured quantity value yi associated with the expanded measurement uncertainty UMP) is lying beyond the specification zone (Figure 3). In this case, the work piece must be rejected.
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reference:VDA