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PPM - wrong parts or defective parts?

#1
Lets say we have agreements with our supplier for PPM 250. Usually PPM shows how many defective parts we get referring to 1 million parts.
But what if supplier send us components which includes some completely "wrong" parts (not defective but completely wrong parts- differents shape etc). To simplify question: if I order one million bolts and this batch also contains 100 nuts, then is it take in account as PPM? Problem is that wrong parts are ruining our automated assembly line. Supplier don't see problems as they say that this is included in PPM and as long PPM is not exceeded, everything is fine.
 

Jim Wynne

Staff member
Admin
#3
Lets say we have agreements with our supplier for PPM 250. Usually PPM shows how many defective parts we get referring to 1 million parts.
But what if supplier send us components which includes some completely "wrong" parts (not defective but completely wrong parts- differents shape etc). To simplify question: if I order one million bolts and this batch also contains 100 nuts, then is it take in account as PPM? Problem is that wrong parts are ruining our automated assembly line. Supplier don't see problems as they say that this is included in PPM and as long PPM is not exceeded, everything is fine.
I'm not sure what the problem is. It seems that while you're asking whether "wrong" parts should be included in PPM calculations (they should be), the supplier is claiming that even including the wrong parts, they're within the specified PPM limit. Do I have this right?
 
#6
I'm not sure what the problem is. It seems that while you're asking whether "wrong" parts should be included in PPM calculations (they should be), the supplier is claiming that even including the wrong parts, they're within the specified PPM limit. Do I have this right?
Yes, you are right. But, what about scrap (for example metal chips) which are mixed with the good parts. Do I have to consider this as part of PPM? If I count all chips in the batch, then probably agreed PPM is broken. Or this is case of part requirements. This is usually shown in part drawing or other documents which is specifing the part requirements (parts must be oil free, burr free and clean etc.). There is also difference if the scrap is sticked to the good parts (then this is calculated in PPM) or scrap is separately in the box (no idea what to do). Both situations are problems to our production line.
 

Al Rosen

Staff member
Super Moderator
#7
Yes, you are right. But, what about scrap (for example metal chips) which are mixed with the good parts. Do I have to consider this as part of PPM? If I count all chips in the batch, then probably agreed PPM is broken. Or this is case of part requirements. This is usually shown in part drawing or other documents which is specifing the part requirements (parts must be oil free, burr free and clean etc.). There is also difference if the scrap is sticked to the good parts (then this is calculated in PPM) or scrap is separately in the box (no idea what to do). Both situations are problems to our production line.
If there are metal chips, the entire lot should be rejected and the total # of parts counted in the PPM. It's a FOD issue that needs to be addressed.
 

Candi1024

Quite Involved in Discussions
#9
If there are metal chips, the entire lot should be rejected and the total # of parts counted in the PPM. It's a FOD issue that needs to be addressed.
Agreed. If you need the parts ASAP and can clean them, then they still count against the PPM and I would look to back charge any significant labor used to bring the items into conformance.

Also you don't count each metal chip as a nonconformance, you count the number of parts that have those metal chips (very likely the entire shipment or crate or box)
 
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