Variation of PA6 material properties between suppliers

[Charon99]

Hi all,

I have a UL certified product that contains plastic parts (PA6). To attain citification all the relevant tests were done by UL including verifying the plastic material supplier was one from their list of certified suppliers.

We wish to change the plastic supplier. UL are insisting that we need to redo all the loading tests for the product. I was arguing that we are not changing the material just the supplier, and the new supplier is UL certified ensuring the quality of the material.
The material properties of the material should not change. They argue that “there is no way of making any comparison of strength and material as they are being manufactured by different companies”. They are different companies but both are manufacturing the same material and are both UL certified (i.e. production is controlled). If we changed the steel supplier, welder, paint line or storage facility no retest is required. If material can vary between manufacturer surely is can vary between batches. We don’t recertify per batch.

Do I have any argument?
Any advice would be much appreciated.

Regards,
Mark

 

[Pud]

I'm afraid that UL are correct.
PA6, like most polymers also has varying amounts of e.g. plasticisers, flow modifiers, nucleation additives, antioxidants, heat stabilizers etc.
Then there's the molecular weight distribution....


Politicians like to panic, they need activity. It is their substitute for achievement.

 

[TugboatEng]

We see this in the automotive world. All manufacturers use PA6 components in their cooling systems yet the European components fail where the Japanese brands don't have issue at all.