Best QC method for controlling failure rate in destructive testing 2

[ProEpro]

We have a product that we buy around a billion pieces of a year. The main quality criteria is break strength in a destructive test. We currently use AQL sampling and reject any lot with more than the threshold of failures. Is this the current best practice for this type of inspection?

We want to reduce the defect rate but I am unsure that lowering the AQL threshold is the right way to go. My experience is QC of dimensions that are not destructively tested. With those CP/CPK type controls work very well. I don't feel they work as well in this situation because we have an average value that is 6 sigma better than the minimum spec but still have a high defect rate. Raising the spec or the average has not helped. Does this mean I have non normal data and need to use different statistics? What are the best measures to use in this situation.

The cost of the product we are testing is low but the cost of testing and rejected shipments is high.

A visual or other inspection can not be substituted for destructive testing.

 

[berkshire]

Expanding on Monkeydogs post,
Do you have Batch/lot identification on the incoming parts ? If you do then you need to grade by supplier A,B ,C. and start sending parts back to the suppliers with the higher reject rates. Composite Pros suggestion of proof testing could be instituted for a short while to get a feel for the real number of substandard parts and see if a re design is warranted. Speaking of Warrantee how is this handled, do you get the bad part back ? or do you simply send them more when the customer complains. Good luck with this.
B.E.

You are judged not by what you know, but by what you can do.

 

[viper3982]

So... let me get this straight.

-Your supplier sells you defective equipment. They have no quality control process to control the failure rate that is as high as 25% of their shipped product.
-You continue to buy from them.
-There is no negative aspect for them aside from occasionally you charge them back for a couple rejects that YOU spend the money to test and find.
-Now you want to give them a 'bonus system for quality improvements'.

I wish *I* was your supplier.

 

The defect rate is 0-10% on the majority of shipments. On 20% of shipments the failure rate is 25%.

OK, I agree that this is an INSANE failure rate for an established product.

This situation has all the hallmarks of Far East sourcing. In which case the defect rate is actually quite low. Naturally this is only remedied by doing the inspection at the source (requiring further off-shoring - see where we're going with this?)


"Everyone is entitled to their own opinions, but they are not entitled to their own facts."