Measurement System Analysis

Question:

Is there ever an exception to the rule about needing full Measurement System Analysis for any instrument placed in the Evaluation / Measurement Technique column on the Control Plan?  If an instrument is listed on the control plan, does it HAVE to have GRRs done, in addition to having to prove stability?  Please base off of ISO 9001 and TS 16949 requirements, and if there is a difference between them for this requirement.   

Answer:

Thank you for this interesting question. Clause 7.6 of ISO 9001: 2008 makes most of this fairly clear. Any monitoring and measuring equipment used to verify conformity of product must “be calibrated or verified, or both, at specified intervals, or prior to use. . .” Notice I made ‘at specified intervals’ bold. This is just to bring to light the importance of calibration cycles. You/your organization can determine what those cycles will be based on the stability of the measuring tool, frequency of use, working conditions, etc. For example, if you were using a micrometer to check close tolerance parts and, you found it a good process to measure the parts frequently, this would be a contributing factor to the decision process. Then, if the working conditions included a lot of cutting fluids or perhaps a good deal of metal dust, another factor is added to the decision process. What I am driving at is this; once you have determined that the product conformity which you are checking is good and/or consistent and that your sample frequency is satisfactory, you would have no definite requirement for GRR’s on the measuring equipment. The calibrations and or verifications you do must be with equipment which is traceable to international or national measurement standards. If you use working standards as gages to check measuring equipment throughout production and those standards are traceable, then you are doing fine. The processes you use to verify the tools and any in-process measuring practices should be documented in Work Instructions or even with the use of photographs or flow charts.

In the second part of your question, you ask if there is a difference between 9001 and TS 16949. I reference section 7.6.1 of TS 16949. Here it is put straight forward:

7.6.1  Measurement System Analysis 

Conduct statistical studies to analyze variation present in the results of each type of MMD that is referenced in the Control Plan.

Use analytical methods & acceptance criteria that: 

Conform to methods and criteria in customer reference (MSA) manuals Or use other methods, if approved by the customer 

This is an automotive sector specific QMS standard. Herein it is necessary to consider safety and liability in everything you do. So, Gage R&R’s are a common practice. Nonetheless, the necessity for these is dictated by individual processes. Some may need them, some may not.

So, if an instrument is listed on YOUR control plan, GRR’s will become a requirement based on all the criteria I’ve noted above. A gage which has proven stability is most often safe from that requirement under 9001 but TS16949 has more extensive requirements.

Bud Salsbury, CQT, CQI

For more about this topic, please visit ASQ’s website.