## EXPANDED MEASUREMENT UNCERTAINTY IN 100% INSPECTIONS

2019-06-19 - **How to apply the second edition of VDA Volume 5 in practice**

Statistical process control (SPC) proves that production processes meet the respective requirements. Since these processes manufacture products, you specify characteristics for each product and measure them. The documentation and even the final proof of capability are based on numerical and graphical results and frequently illustrated in quality control charts.

National and international standardisation, however, agreed on a definition describing SPC in terms of process control but involving the aspect of process improvement, too. Statistics of machine performance studies, measurement system and process capability analysis play an important role. Are you acquainted with this subject?

- C
_{pk}is by 0.33 less than C_{p}which is by 0.33 less than C_{mk}which is by 0.33 less than C_{m}. - C
_{m}is greater than C_{pk}in most cases. - C
_{mk}and C_{p}are frequently equal.

- The deviation of the determined C
_{m}/C_{mk}value from the actual C_{m}/C_{mk}value is calculated from the MPE specified for the measuring instrument. - The greater C
_{g}, the more approaches the actual C_{m}/C_{mk}value the determined value. - C
_{g}does not affect the difference between the determined and the actual C_{m}/C_{mk}value.

- Not a single measured value may exceed specification limits.
- Not a single subgroup average may exceed control limits.
- An average of 300 subgroup averages will exceed the control limits.

- Coordinate measuring machine
- Multi-spindle turning machine
- Bottle filling system

Our Q-QUIZ is published once a month. You can find the answer to all questions of the current quiz in the PDF file below.

This quiz was originally published in the April issue 2017 of the German magazine QZ Qualität und Zuverlässigkeit (http://www.qz-online.de/).