Process capability for blended fluids? PPAP book section 1.2.2.9.1, page 6

[Noelia]

Hello, first post here! Of course it’s a question...

We need to do a process capability study for a product that requires PPAP. My problem is that we manufacture fluids (blended in 19,000 gallon tanks), we do not run many batches per year. And this product is a NEW product. Typically we manufacture these types of products about 5-12 times a yr.

The PPAP book (section 1.2.2.9.1, page 6) says you have to have 100 readings in 25 subgroups - ???

Our customer's QE is used to dealing with 'hard parts' not with fluids so they're not much help either. I get the feeling think they want me to propose something that looks halfway decent so that they can pass *their* audits.

I did some searching in the site but couldn't find much if any info on doing PPAP on fluids. Unless I missed something, if so please let me know of any possible threads with guidance!

Thanks!

 

[Jim Wynne]

The PPAP requirements allow for "...other methods more appropriate for certain processes or products..." with prior customer approval. I have a feeling that perhaps you should be dealing with the Bulk Material requirements (see page 67 in the 3rd Edition manual), and you should work with your customer to determine the appropriate process capability criteria and reporting requirements.

 

[Noelia]

Thanks for your comment, Jim. I checked in the back section, F-10 (p. 77) just says what I said - that there's no one way to do this.

SO, I need to come up with *something* to put in the PSW... all I can come up with is to pick a key characteristic for the new product that is also measured in a current product and chart out results for the last year (all 12 batches) to show we have a trend of being 'in spec' (don't have enough data pts to show we're 'in statistical control'). I could even do an Individuals-Moving range chart.

Does that sound reasonable? Any other suggestions would be great too.

 

[Dave Dunn]

Would it be reasonable to do "random" sampling using multiple samples from the same batch? How is the product contained or packaged after the large blending batch? If it's in smaller containers, maybe you could take periodic samples from the pour process.

 

[Jim Wynne]

Thanks for your comment, Jim. I checked in the back section, F-10 (p. 77) just says what I said - that there's no one way to do this.

SO, I need to come up with *something* to put in the PSW... all I can come up with is to pick a key characteristic for the new product that is also measured in a current product and chart out results for the last year (all 12 batches) to show we have a trend of being 'in spec' (don't have enough data pts to show we're 'in statistical control'). I could even do an Individuals-Moving range chart.

Does that sound reasonable? Any other suggestions would be great too.

Noelia,

The AIAG requirements for bulk commodities are different from the standard PPAP requirements for a reason. A lot of the standard requirements don't make sense for bulk materials. You need to discuss this with your customer, and explain that the bulk requirements make more sense, and ask them to explain to you exactly what they expect with regard to process capability reporting.

 

[Noelia]

If it's in smaller containers, maybe you could take periodic samples from the pour process.

No, we sell the product in bulk (truckload) to the customer. Otherwise your idea would be a good one since we'd be doing process capability analysis on the packaged product (which we actually DO but for other products/ customers).

and ask them to explain to you exactly what they expect with regard to process capability reporting.

Agreed! But I think my customer wants to hear my suggestion, their QE sounded pretty clueless when it came to bulk materials and process capability. I was hoping for some ideas from the sage people in this board... I was hoping someone has had a similar situation.

 

[Tim Folkerts]

To quote Jim (who was quoting the AIAG):

The purpose of PPAP is to determine if all customer engineering design record and specification requirements are properly understood by the supplier and that the process has the potential to produce product consistently meeting these requirements during an actual production run at the quoted production rate.

It would seem to me that showing you have been able to consistently meet similar specs in the past would indicate that you have the "potential to produce product".

Would it be possible to mix up and test a smaller sample batch and show that it meets specs? If you can show that you know the right starting materials, mixing procedures, etc, and can produce a batch that meets the specs, then you have also shown "requirements are properly understood"


Just my $0.02.

Tim F