What does a level 1 (PSW) PPAP actually promise?

[Dan M]

That is a tricky question to answer because it is almost impossible to foresee all of the potential effects on your customer even when you thoroughly test. For example, a former company once made a change to a supplier of steel coil used for a suspension bushing. The only discernable change was a slight reduction in a flange thickness, which was still within spec, so we did not notify our customer. The first shipment jammed their automated feed line, something we never considered. It also depends on how well you know all of the bulk material characteristics and understand how they will impact your customers.

This is also my thinking. Just because the product continues to meet the published customer specification after we make a raw material change does not mean the product will continue to perform correctly in the application.

 

[outdoorsNW]

In Miner's case, it sounds like a revised PPAP would likely not have prevented the problem. Since parts made with the new material was still in spec, the supplier likely would have accepted the revised PPAP and only discovered the problem when new parts actually arrived. The root cause of that problem was not the supplier but rather the customer who allowed a thickness that would cause problems at the customer. In a case like that an email to the customer would have been as useful as a revised PPAP.

 

[Howard Atkins]

PPAP all levels

DECLARATION
I affirm that the samples represented by this warrant are representative of our parts,
which were made by a process that meets all Production Part Approval Process Manual 4rd Edition Requirements. I further warrant that these samples were produced at the production rate of______/____ hours
I also certify that documented evidence of such compliance is on file and available for review. I have noted any deviations from this declaration below.

This is your word which you sign at submission any thing else is fluff

 

[Miner]

In Miner's case, it sounds like a revised PPAP would likely not have prevented the problem. Since parts made with the new material was still in spec, the supplier likely would have accepted the revised PPAP and only discovered the problem when new parts actually arrived. The root cause of that problem was not the supplier but rather the customer who allowed a thickness that would cause problems at the customer. In a case like that an email to the customer would have been as useful as a revised PPAP.

It actually would have in this particular case as the OEM had a CSR that all product supplied to this facility physically be submitted in sufficient quantities to test out on the automation prior to PPAP approval. Your point would still be valid in many other cases.

 

[Matt's Quality Handle]

You never know what kinds of problems an unauthorized change can cause.

I had a supplier close down one of their plants in Kentucky, and ship to me from one of their other facilities in Detroit without notifying me. One of the side effects was that I ended up walking in on two second shift operators quite literally with their pants down.

 

[Howard Atkins]

. One of the side effects was that I ended up walking in on two second shift operators quite literally with their pants down.

That is why we audit all shifts

 

[Matt's Quality Handle]

That is why we audit all shifts

But, do we audit second shift at 6 pm on the Friday leading into Memorial day weekend?

When all of the office/management type people SHOULD have skipped out already. I get flashbacks every Memorial day!

 

[Dan M]

I would like to revive the discussion from last fall with a follow-up question. The table in the PPAP manual Section 3.1 - Customer Notification indicates in #9 that "Additionally for bulk materials: New source of raw material from new or existing supplier" is an example of a change requiring [customer] notification. Then it provides clarification, stating "These changes would normally be expected to have an effect on the performance of the product." What if we do not believe that a change in raw material source would have any effect on the product, because the alternate raw material is chemically equivalent and has identical properties?

 

[John Predmore]

@Miner gave a IRL example (in this thread) where the potential impact of an innocent supplier change was unknown and unknowable. PPAP is a risk-reduction activity. Even when you are 99% certain there would be no impact from a change, customer notification of changes is your liability reduction insurance to avoid the costly 1% 'gotcha'.

a former company once made a change to a supplier of steel coil ... The first shipment jammed their automated feed line, something we never considered.

 

[Miner]

What if we do not believe that a change in raw material source would have any effect on the product, because the alternate raw material is chemically equivalent and has identical properties?

I don't know which industry that you are in, but my experience with raw materials in the rubber industry was that any change in supplier had a noticeable effect on the final properties. We always had to make adjustments in the formulation to compensate.

For example, carbon black is >97% carbon with three main properties, particle size, structure and surface chemistry (the remaining < 3%). While different suppliers can closely match a specified particle size, their different processes result in different structures, which has a strong effect on the properties of a rubber formulation. The same with surface chemistry.

Do not make the mistake of thinking that material properties are solely determined by their chemistry.