Capability studies with less than 125 individual samples.

Dear Fellows. . .

We did some capability studies with 25 individuals samples to analise some processes without security characteristics.
Even though I know that it´s not corect, it is impossible for us to it with 125 samples, because it would give us to much work, and wouldn´t be able to spend the necessary time.
The auditor didn´t accepted this studies and even adviced us that it is better stop doing capability studies instead of doing it this way.
Anyway we want to them for our control. Is it possible? How could we deal with this problem?

Fire your auditor.

Seriuosly, here is a true life story about capability studies.

One day the customer made a change to the plastic material requirements. The supplier had 4 tooling sets, 8 cavities each. Each part had 6 "critical" characteristics. To perform a "legal" PPAP submission, there were to be 19,200 measurements taken. We told the customer that this would be 800 hours total elapsed time. (Long ago a complete PPAP submission was calculated as 2.5 minutes per "critical" dimension as an elapsed time, for PPAP timing purposes.) The customer agreed to 25 samples per cavity, to cut down the time. That's only 4,800 total measurements. Don't you think they will understand the impact of the process change with that many parts?

Point is, get the blessing from your customer that 25 is enough, defend that to your auditor. Defend in that the purpose of a capability study is a determination of a sample meeting some specification. 25 RANDOM parts could be enough, particularly if as you say there are no critical characteristics.

But remember the AIAG SPC manual states 100 parts. This usally applies to key or critical characteristics.

[Marc]

Not to be off subject, but thses types of costs should be considered during contract review. If it costs you $4000 to rePPAP after a change, who picks up the tab for expenses associated with this unplanned change?

[Laura M]

Marc,
Have you seen where a customer "pays" for the PPAP costs? My experience is customers say "do this now" - may consider a piece price increase, but flat charges, no way.
Perfect example, after initial PPAP, the customer asked us to "hold" parts for 24 hours and perform a check..piece price/handling charges were agreed to. Then we have to add the step to the PFMEA, PCP, source warrant, etc...no engineer change level, but a process change. Last week, they said, change the "HOLD" time to 48 hours, and perform the same check. So technically, no "additional" labor, but the update the PPAP documentation came up. (FYI, the reason the parts are being held & checked is a design issue, and the customer is design responsible) Yeah, it's an ammendment to the contract and should go through a Contract Review process, but its kind of like a lightweight arm wrestling a heavyweight. 4.3.2.d "all reqt's...shall be met" become the suppliers responsibility. Would love to have a clause in the initial contract showing a flat charge for subsequent PPAP's. Has anyone done this successfully?
Laura

[Spaceman Spiff]

I've been through similar situations in the past and was never able to recoup administrative costs, i.e., minor print changes such as error corrections (on customer's print) but still require PPAP to the latest print rev. The B3 is like 10 ton elephants... when they feel like trampling through your house, all you can do is follow after them with a shovel.

[Marc]

I can't say I've seen a flat rate. Most of the time companies just do what they're told. That's up to the company until they see they're losing on a contract. I saw one company which, due to a customer's reduced volume (attibuted by GM to 'bad sales for that model that year'), ended up actually paying a nickel a piece for GM to 'buy' them. They never addressed reduced volumes from the original contracted volume in contract review.

This all said, yes - if you want to sell to automotive you have decided to house the gorilla for a while. If I ran a company selling to the automotive industry, I'd want safe guards. PPAPs are not cheap. Contractr review is the place to adderss such issues.

"... Yeah, it's an ammendment to the contract and should go through a Contract Review process..." Yup - sure it (or should be...)

Thank you all for your help. It is really very difficult to deal with our costumers.
We´ve discussed with our consultor and he suggestes us to do ICm (mini machine capacity) instead of capability studies.
This study can be done with 10 samples, and will be problably enogth for us to control our process, considering that we will use it just when there is no "shield" in the process.
Asking a Waiver for the costumer would be a good idea, altough it would be very difficul to recieve it.
What do you thing about it?

[Sam]

We have just completed our QS9000
registration audit and one of the observations was pertaining to an incomplete PPAP; capability study missing from data package.
Dilema:
Our PPAP sample size consists of one piece. We send the sample to the customer (Chrysler)with a level I data package, they fit it to the vehicle, evaluate and accept/reject.

The auditor has requested that I conduct a capability study.
Any suggestions would be greatly appreciated, I need to respond by 3/15/00.