In the world of precision manufacturing and dimensional metrology, the difference between a "pass" and a "fail" is often measured in micrometers. However, even the most accurate measuring instruments are subject to uncertainty. This is where the becomes the backbone of industrial decision-making.
If a quality inspector measures the shaft and the reading is
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Thus the specification limits are , but the acceptance limits for proving conformance are 10.02–10.08 . INTERNATIONAL STANDARD ISO 14253 1.pdf
The measured value must fall outside the specification limits by at least the expanded measurement uncertainty.
: Measured value = 20.040 mm → above 20.035 but below 20.05 + 0.015 (20.065) → Indeterminate (cannot prove conformance or non‑conformance).
Applicable to GPS characteristics of workpieces and measuring equipment. In the world of precision manufacturing and dimensional
ISO 14253-1 is an international standard that establishes rules for determining whether a manufactured workpiece (or a population of workpieces) conforms or does not conform with a given tolerance. Crucially, it provides a procedure that formally accounts for the unavoidable when making this decision. It applies not only to workpieces but also to measuring equipment, using the concept of maximum permissible errors (MPE) instead of tolerances.
Detailed, step-by-step methods for binary and non-binary decisions. Annexes: Examples of how to apply the rules.
The standard's scope is precisely defined. It applies to: If a quality inspector measures the shaft and
This is the most practical part of the PDF. It walks through 12 real-world scenarios (shafts, holes, gauges) showing exactly when to accept, reject, or re-test.
on both sides. This reduced area is called the . The subtracted regions are known as guard bands . 2. Proving Non-Conformity (Rejecting a Part)