What gage studies are required for PPAP?



When I make disposition on supplier PPAP's I always ask for gage studies for ALL measurement and test equipment used to manufacture the part (per the control plan). I am challenged by the suppliers sometime because there may not be any critical or significant characteristics on the design record or the control plan. They think that only the equipment used for statistical purposes needs to have studies performed. Who is right?


Al Dyer

I think you are the customer and you decide what you want. Just because there are no critical dimension called out there is still a need for gage studies. I would say at a minimum you should require:

Gage R&R

studies for all types of gages that are used to qualify the dimensions you are monitoring.

If a gage (type) is used to verify conformance to specification it should go through the entire MSA process.



PPAP third edition states in I.2.2.10 “The supplier shall have applicable Measurement System Analysis studies, e.g. gage R&R, bias, linearity, stability studies, for all equipment used for new or modified gages, measurement, and test equipment.

QS9000 third edition states in 4.11.4 “Appropriate statistical studies shall be conducted to analyze the variation present in the results of each type of measuring and test equipment system. This requirement shall apply to measurement systems referenced in the Control Plan”.

If it is used to determine conformance to spec and listed in the Control Plan, it should under go a MSA study. The key here is the words applicable and appropriate. You have to give you supplier a little bit of latitude on the selection of statistical tools to qualify the gage. But the rule of thumb is as AL listed… R&R, bias, linearity, stability studies.


Al and JJ,

Thanks for your comments. I will also be contacting my QS auditor from Entella with the same question. I am very familiar with Third Edition PPAP and QS requirements but when I keep hearing the same "argument" regarding gage studies it's time to gather some written documentation other than the AIAG published requirements. For some reason a lot of people loosely interpret the QS requirements.
We are doing a PPAP for a customer in the automotive industry (Chyrsler/Daimler). We have completed most of the PPAP and turned it in, but we need to do a R&R Gage study and an Early production Coantainment (GP12). Being new to this, I dont quite understand what this calls for. If you have any information or forms you can pass my way, it would be greatly appreciated. Like I said we are new to this, and anything you can send us would help me out a great deal. If you can, please contact me with anything thing that might be useful to us.
Thank You Very Much,
George :)
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