The procedures described in this document are based on the ISO/IEC Guide 98-3 (Guide to the expression of uncertainty in measurement) (GUM)  and on ISO/TS 14253 (Inspection by measurement of work pieces and measuring equipment, Part 1: Decision rules for proving conformance or non-conformance with specifications) .
VDA Volume 5 also contains the well-established and widely used procedures of the MSA manual  that are used in order to evaluate and accept measuring equipment. It provides some information about the validation of measurement software as well.
In order to ensure the functionality of technical systems, single parts and assemblies have to keep specified tolerances. The following aspects must be considered when determining the necessary tolerances in the construction process:
- The functionality of the product must be ensured.
- Single parts and assemblies must be produced in a way that they can be assembled easily.
- For economic reasons, the tolerances should be as wide as possible, but for functionality reasons, it should be as narrow as necessary.
- The expanded measurement uncertainty must be considered in statistical tolerancing.
Due to the measurement uncertainty, the range around the specification limits does not allow for a reliable statement about conformance or non-conformance with specified tolerances. This might lead to an incorrect evaluation of measurement results. For this reason, it is important to consider the uncertainty of the measuring system and the measurement process as early as in the planning phase.
German language version.