PPAP Capability Study - Infrequent batches - Conductor paste

[Chantal P Tardif]

I have a supplier to who I am requesting a PPAP submission. The only thing is that he is telling me that he can't do a full capability study since it takes 100 samples to performe the capability study. His process is producing conductor paste. So he produces a big batch once per three or four months. So he is telling me that his capability study would take over a year to do. So my question is the following, could this study be done on a 100 samples of this batch to verify the resistivity and viscosity in that same big batch to see the overall capability and then a long term capability study over the variability of this process from batch to batch. I'll wait for anyone response since I would require both but I don't want to be out of line. Thanks for your help!!!

 

[Howard Atkins]

I dont see why he cannot take samples every half hour or so and measure the capability like this.
In plastic injection I produce a large number of parts in a lot and I take the capabilities according to these individual pieces.
The point as I see it is to show that the process is stable and thus to take samples at a reqular interval shows the stability of the process.

 

[Casana]

I know this is an old thread but it is similar to my current question...
We manufacture semiconductor devices, several thousand devices are created at the same time on a wafer.
For us to collect samples from 100 wafers is not practical - the time to run them would be months, and the cost would be huge.
So... can I just collect a lot data points from 3-5 wafers and estimate a Ppk, in order to submit the PPAP? The customer for this particular product is not an automotive one and they are not requiring PPAP (but our QS registration does!)
Thanks for any input.

 

[Al Dyer]

Chantal,

I assume by your post to the APQP/PPAP forum that you are already a tier I supplier to automotive.

Do you have two systems for part submission, one for automotive and one for non-automotive?

If you do, it sounds like a problam waiting to happen. I believe that if there is only one system to follow, there will be alot less headaches and confusion.

IMHO ASD...

 

[D.Scott]

Casana - Are you certain your QS registration requires you to do PPAP submissions for non automotive customers? My understanding is the instructions of the customer over-ride all requirements. If your customer states in a quote request that PPAP is not required, I don't think you can be held to PPAP requirements. Like Al says, two seperate systems is looking for trouble so we do "PPAP" as part of APQP even if it is not required. Some of the others would be more informed on this but IMHO, I don't think the QS requirement needs to compel an expensive study. I would use my ongoing process data to illustrate capability.
Dave

 

[AJLenarz]

Chantal,

Your description of the product (conductor past, one batch every 3-4 months) would be considered “Bulk Material”. The PPAP rev 3 addresses this in Section I.2.2.9.6. In a nut shell it states, if you can’t or don’t have capability, you must do 100% inspection. 100% inspection means an evaluation of samples(s) of product that is representative of the entire production run.

Make sure his control plan states that 100% inspection will be perform in lieu of capability.

Does this clear things up?

 

[Casana]

OK, I re-read the PPAP requirement. It DOES state in Note 2 that the Customer & Supplier need to agree on what index to use.
NOW - the next question is... what index is appropriate for processes that don't lend themselves to easily collecting 25-100 samples/lots in a timely/ cost effective manner? ie - Do manufacturers of equipment have to do Cpk's or what do they use???