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Receiving Inspection: C of C for resins

Proud Liberal

Quite Involved in Discussions
Having come from an automotive environment, I have been used to getting Certificates of Compliance that meet the following:
1. Printed on company letterhead
2. Complete identification of material
(including lot number, date of mfg)
3. List of tests/inspections performed
4. Standards used is testing
(i.e. ASTM)
5. Tolerances
6. Actual test/inspection results
7. Person certifying results
a) signature
b) printed/typed name
c) printed/typed title

I am now working in a plastic extrusion house that is attempting ISO cerification. Per § "The supplier shall ensure ...... until it has been inspected or otherwise verified as conforming to specified requirements." I thought this would be easy to comply with by simply requiring C of C's with each resin shipment.

Not all of my suppliers are willing and/or capable of providing what I consider an acceptable certification. My real concern goes beyond an ISO compliance. How can I protect my customers from an interruption of deliveries if I inadvertantly accept material as good based on a letter of certification without test results only to find that the resin won't process at the time of manufacture.

Am I overcomplicating this? Is there an easier solution? Based on our size and volume of work, I cannot justify setting up an internal lab.

Any advise would be greatly appreciated.



Captain Nice
Staff member
A CofC (Certificate of Conformance) typically does not have, by definition, data. It;s just a piece of paper saying "We swear this is good stuff."

What you are used to getting with data is really more than a basic CofC.

You have to judge risk. If you're getting data your rish should be low - so you might want to 'ship to stock' their material. No data? Then you have to determine what you consider acceptable as a check on your end. Part of your determination should include the effect of accepting and using bad material.

Bottom line - you do a basic risk analysis. In the QS world this is supposed to be addressed in the Process FMEA - Actually it's the first step of the PFMEA.


Super Moderator
Super Moderator

What Mark said is correct, you have been receiving test reports on your material, not certificate of compliance.
Talk to your suppliers and see what they can provide. Perhaps they, too, do not have the facilities to run an internal lab and are relying on their supplier's test data (which could then be forwarded to you with the shipments).
Of course, what you do needs to be based in reality. Are you making rocket parts, or lego's?


What you are use to getting is a C of A (certificate of analysis).
We do both plastic injection molding and metal machining. I receive a material certification detailing the chemical composition for metals (material certification or certificate of analysis), but only a C of C (certificate of compliance) for plastics. I compare what we ordered to what they say they send us and that's that. That is our receiving inspection for plastics, since we do not have a chemical lab. The way we justified this "simple" inspection is because in 26 years we have had no cases of having bad resin. It is written in our procedure that the C of C will be sufficient. We do have a few instances where our customer requires actual test results on the raw resin to be sent to them (usually at PPAP stage), so we deal with those on a one on one basis.
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