S
Salman
We are trying to resolve a very high rate of rejection in a part. We know that tensile strength of a small ring used in the part needs to be maintained within spec.
We have pursuaded our supplier to send us tensile certs with every shipment. In order to include this requirement somewhere in our system, our (Design) Engineer made the tensile on drawing to be a critical dimension. (Even though criticals are mentioned on drawing to mention criticality, and not to get certs).
Now our supplier says that since we have made tensile a critical dimension, they are bound to do Cpk on tensile, every time they run the parts in furnace ... which is not possible (min. 30 readings would be required).
My understanding was that even though tensile is critical dimension on drawing, we do not need them to do Cpk every time, rather they only need to do it once during PPAP. Sadly (for me), this suggestion was knocked down by the supplier's Quality representative. He said that as per AIAG manual, every characterisitic with critical on it, HAS to have Cpk done everytime it is run.
Unforunately, I don't have AIAG manual with me right now. And he does seem right in this statement. Still I think it is weird that we (customer) are BOUNDED by some manual to have Cpk done on a dimension, EVEN IF WE DO NOT NEED IT.
What do you guys think about my suggestion to the supplier?
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By the way, in the end I pursuaded the Design Engineer to take off the critical from tensile, because critical is put on drawing for functioning, and not merely to get certs. He then added a note on the drawing saying something like tensile certs are to be accompanied with each shipment.
We have pursuaded our supplier to send us tensile certs with every shipment. In order to include this requirement somewhere in our system, our (Design) Engineer made the tensile on drawing to be a critical dimension. (Even though criticals are mentioned on drawing to mention criticality, and not to get certs).
Now our supplier says that since we have made tensile a critical dimension, they are bound to do Cpk on tensile, every time they run the parts in furnace ... which is not possible (min. 30 readings would be required).
My understanding was that even though tensile is critical dimension on drawing, we do not need them to do Cpk every time, rather they only need to do it once during PPAP. Sadly (for me), this suggestion was knocked down by the supplier's Quality representative. He said that as per AIAG manual, every characterisitic with critical on it, HAS to have Cpk done everytime it is run.
Unforunately, I don't have AIAG manual with me right now. And he does seem right in this statement. Still I think it is weird that we (customer) are BOUNDED by some manual to have Cpk done on a dimension, EVEN IF WE DO NOT NEED IT.
What do you guys think about my suggestion to the supplier?
---------
By the way, in the end I pursuaded the Design Engineer to take off the critical from tensile, because critical is put on drawing for functioning, and not merely to get certs. He then added a note on the drawing saying something like tensile certs are to be accompanied with each shipment.