O-Ring/Seal PPAP Advice
Hi All.
Looking for some tips or advice. Coming up short on reaching out to contacts and Google searches – was hoping someone on here may be able to help.

The company I work for has been requesting PPAP documentation from our suppliers for about 4 years. We were mainly concentrating on the metal components or other rigid material of our products, and getting PPAP documentation (MSA, Cpk, Control Plans, Dimensional, etc.) from these suppliers has not been an issue. However, we just started requiring the same PPAP documentation from our seal/o-ring suppliers and am finding out we are horribly unprepared. We basically approached these suppliers with a “business as usual” mentality and received some major pushback.

Our prints only have very basic information on them such as seal/o-ring OD, ID, and height, but do not state other requirements. When our engineering group was questioned about the lack of information on these prints, they responded that most of the missing information was proprietary and we could not get it from the supplier.

For those of you with experience in the plastics/elastomer industry, what type of information is typically on these types of prints? Also, what type of PPAP documentation should we be requesting to ensure lot-to-lot receipts are consistent? Any other tips or advice?

Thank you very much in advance for any help you may be able to provide.
4 Replies
Hello George.  I've been in similar situations. 

For those of you with experience in the plastics/elastomer industry, what type of information is typically on these types of prints?  Durometer and material type in addition to dimensional.  It is unlikely the supplier is using proprietary material because standard design references are published by manufacturers so design engineers can choose them for applications...just like metal products.  Oil rings/seals are classified into chemical and temp resistance categories. etc.    

Also, what type of PPAP documentation should we be requesting to ensure lot-to-lot receipts are consistent?  You mainly want the material type on the drawing so you can have a supplier submit a cert and track chemistry conformance.  That or they may choose to bind themselves with a test report in accordance with like an ASTM std. Suppliers are only required to submit PPAP data pursuant to a drawing or tech spec.  So if your company doesn't provide that or if that wasn't part of the original contract, a PPAP submission may need to be re-negotiated.  PPAPs cost.  That may be part of the reason for pushback.  However, you shouldn't be getting pushback from your own DE's...only cooperation. Are you in the automotive industry?
David -Thank you for your response. I wasn't aware O-rings/seals would be classified into the chemical and temp resistant categories. This gives me another route to investigate.

As for the pushback, the supplier is stating the print dimensions on the seals have zero effect on the form, fit, and function of the parts  and an MSA and/or Cpk for PPAP have no bearing on the overall performance of the seal from one lot to another. This response makes me believe they may not have an understanding of what or why MSA's and Cpk's are valuable. My belief is both are key assets to help predict lot-to-lot performance.

Our company is not automotive, but an OEM supplier to several different fields with the core of our business in oil and power generation. We have been following a modified AIAG format for our quality documentation.
PPAP is not meaningful without a clear specification.  O-ring type of commodities are too often hiding behind the cloud of "proprietary information".  Be frank, I've used that to push back the unreasonable requests from our client's engineers.

My coaching to my team are using functional requirements to spec instead using the inputs.  Instead put spec on the print to restrict supplier's selection on materials or processes to produce products; having your design engineers to put the functional requirement on the prints so your suppliers may select the optimal solutions for you.

For example, instead of spec out the durometer for your suppliers, it makes more sense to state that the o-rings shall not have shrinkage under certain temperature (based on the application environment) or maintaining dimensional consistency under certain type of pressure.  Or spec out the o-rings must resist chemical such as diesel, gasoline, heat, sunlight, etc. instead of calling out the specific material (rubber, etc.)  It is their responsibility to ensure their product to support your needs but it is your engineers to determine what are the characteristics that would ensure your product will perform as intended.   

Things will be easier if your company knows how to define the functional requirements.  From the point on, you can simply ask your supplier "how can you make sure your product will meet the requirement ___% of time?"  Then you will have your CpK answers (of course come with MSA to prove the gages are up to the job).  Of course, even it is the right approach but it doesn't mean that's an easier approach.  It is 100 times easier to pick up a o-ring that happen to fix the problem during PV&V and put that on the print without knowing why it got fixed.  But I can tell you with certainty that you can make your suppliers fail all the time by not telling them how you define "quality" for the specific parts. 
Thank you, Kaiwen. This may be where our supplier was coming from. I've forwarded yours and David's suggestions to our engineering department and will be having a follow up meeting with them to discuss.

Thank you again for the help!