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The focus of this reference manual is measurement systems where the readings can be replicated for each part. Not all measurement systems have this characteristic; for example:

 Destructive measurement systems
 Systems where the part changes on use/test.

The following are examples of approaches to the analysis of measurement systems, including those not previously discussed in this manual. This is not intended to be a complete listing covering every type of measurement system but only examples of various approaches. If a measurement system does not fit the manual’s focus, it is recommended that assistance from competent statistical resources be consulted.

Destructive measurement systems

When the part (characteristic) being measured is destroyed by the act of measuring the process is known as destructive measurement. This includes the whole class of measurement systems known as “destructive measurement systems”; for example destructive weld testing, destructive plating testing, salt spray/humidity booth testing, impact testing (gravelometer) or mass spectroscopy and other material characteristic testing processes.

These are the “classic” examples of a non-replicable measurement system since repeated readings cannot be taken on any single part.

Systems where the part changes on use/test

However, there are other measurement systems which are non replicable where the part, itself, is not harmed by the measurement process but the characteristic being measure will change. Examples of this are: leak tests with qualitative data, testing using engine test stands, transmission test stands, vehicle dynamometers, etc.

Analysis of these systems will depend on whether:

1) A homogeneous set of parts (small between part variation) can be found to represent a single part;
2) The shelf life of the characteristic (property) is known and extends beyond the expected duration of the study – i.e., the measured characteristic does not change over the expected period
of use; or
3) The dynamic (changing) properties can be stabilized

source : Analysis of measurement systems

Post Author: ghaemi mohammad

This site has been established to provide updated and specialized information in the field of quality management systems and to share my experiences in the field of conformity assessment and promotion and promotion of this science.

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