Stop treating measurement results as absolute truth. Use the rules of ISO 14253-1 to align your production, quality control, and customer acceptance processes. It protects both the manufacturer (from unnecessary scrap) and the customer (from bad parts).
For measurement results that fall within the uncertainty range of the specification limits (i.e., ( x \pm U ) overlaps one or both limits), the standard does not force a decision. This is the . In this region, it is impossible to declare either conformance or nonconformance with the required level of confidence. In practice, this may require additional actions, such as using a more accurate measurement method or renegotiating the specification.
): Estimate the expanded uncertainty of your measurement process using ISO/IEC Guide 98-3 (GUM). INTERNATIONAL STANDARD ISO 14253 1.pdf
ISO 14253-1 is a technical standard developed by (the technical committee responsible for dimensional and geometrical product specifications and verification). Its full title is: "Geometrical product specifications (GPS) — Inspection by measurement of workpieces and measuring equipment — Part 1: Decision rules for verifying conformity or nonconformity with specifications."
It is part of the ISO GPS matrix system, which ensures that specifications (drawings), measurement, and verification processes are aligned internationally. Scope of the Standard Stop treating measurement results as absolute truth
In perfect mathematics, a tolerance boundary is a sharp, black-and-white line. For instance, if a steel pin must possess a diameter between and , any pin measuring is scrap, and any pin measuring is perfect.
To declare a workpiece or measuring instrument compliant, the measured value must fall entirely within the tolerance limits, . The Rule: For measurement results that fall within the uncertainty
This mutual approach balances the risks between the two parties and provides a fair, transparent basis for quality agreements.