Capability studies with less than 125 individual samples.

D

Dan Reicher

#1
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?
 
Elsmar Forum Sponsor
B

Batman

#2
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

Hunkered Down for the Duration
Staff member
Admin
#3
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?
 
L

Laura M

#4
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
 
S

Spaceman Spiff

#5
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

Hunkered Down for the Duration
Staff member
Admin
#6
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...)
 
D

Dan Reicher

#7
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?
 
S
#8
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.
 
D

Dan Reicher

#9
I am not sure if it will help...

In our case we submit the PPAP with 10 pieces, as chrysler askes us, even though we don´t any oficial document. To sovle this problem we are asking them a waiver, to allow it and to let us give them capability studies from the further product because they are very similar and there are no changes in the process, just in some components.
 

Marc

Hunkered Down for the Duration
Staff member
Admin
#10
Originally posted by Sam:
The auditor has requested that I conduct a capability study.
The heck with the auditor and what s/he requests. Your customer is supposed to tell you what they want - not your auditor. The auditor has no place telling you to do a capability study if not requested or required by your customer.

Get your customer to tell you, preferably in writing, what they require. Get a waiver if necessary. Remember, you can get a verbal waiver. Record the person (and their title) who is giving the waiver, the specifics of the waiver, the time of day and date you spoke with the person, and the phone number you reached him/her at.



[This message has been edited by Marc Smith (edited 04 March 2000).]
 
Thread starter Similar threads Forum Replies Date
D O Ring capability and measurement - What is the automotive 'norm' for capability studies on O Rings? General Measurement Device and Calibration Topics 3
E Sampling for capability studies for variables and attributes Capability, Accuracy and Stability - Processes, Machines, etc. 4
T Results from conducting a Capability Studies Statistical Analysis Tools, Techniques and SPC 4
B For a measuring instrument, should MSA be done first or the Capability studies? Gage R&R (GR&R) and MSA (Measurement Systems Analysis) 4
R Excel 2003 and Capability Studies for Dummies - Help needed! Excel .xls Spreadsheet Templates and Tools 4
L Capability studies on machine types - Supplier has over 1000 machines Quality Manager and Management Related Issues 7
M Capability Studies in Engineer to Order Small Batches Capability, Accuracy and Stability - Processes, Machines, etc. 5
S Specification Limits and Capability Studies in Minitab Statistical Analysis Tools, Techniques and SPC 9
A Capability Studies for Profile (GD&T Callout) Capability, Accuracy and Stability - Processes, Machines, etc. 6
O Capability Studies: Can I combine Attribute Data and Variables Data Capability, Accuracy and Stability - Processes, Machines, etc. 2
B Injection Molding Capability Studies for PPAP Submission Capability, Accuracy and Stability - Processes, Machines, etc. 19
Chennaiite Interpretation of Short term vs. Long term Capability Studies Statistical Analysis Tools, Techniques and SPC 3
M Machine Tool Calibration - Machine Capability Studies on CNC Machine Tools Manufacturing and Related Processes 5
M Volumetric Positioning - Machine capability studies for CNC machine tools General Measurement Device and Calibration Topics 4
H Capability Studies and Monitoring Runs at a Metal Stamping Facility Statistical Analysis Tools, Techniques and SPC 5
I Reason for pre-production machine/process capability studies / SPC during production Capability, Accuracy and Stability - Processes, Machines, etc. 3
M Differences between Machine Capability and Product Capability studies Capability, Accuracy and Stability - Processes, Machines, etc. 9
F Capability studies in Process Plants - E-coat of galvanized flat carbon steel coils Capability, Accuracy and Stability - Processes, Machines, etc. 1
J Safety Characteristics & capability studies Statistical Analysis Tools, Techniques and SPC 3
D Machine Capability Studies on CNC Lathes Statistical Analysis Tools, Techniques and SPC 35
D Machine Capability Studies: How many parts needed? Statistical Analysis Tools, Techniques and SPC 11
J Capability Studies - Do I need to use subgroups? Statistical Analysis Tools, Techniques and SPC 1
J Multi-Cavity Capability Studies Statistical Analysis Tools, Techniques and SPC 1
D Capability Studies - 5 different dimensions - How many parts? Statistical Analysis Tools, Techniques and SPC 6
I Capability Studies - Fewest Number of Parts for a Capability Study Capability, Accuracy and Stability - Processes, Machines, etc. 9
D Capability Studies - Combining parts from two lots Statistical Analysis Tools, Techniques and SPC 17
Marc PPAP Preliminary Capability Studies - Batches - Paint Company APQP and PPAP 3
Q Capability - CPk comparison values Capability, Accuracy and Stability - Processes, Machines, etc. 12
R Capability analysis - What is going on this chart? Manufacturing and Related Processes 15
H Capability Data for Paint Thickness on Painted Parts Statistical Analysis Tools, Techniques and SPC 10
N Is capability applicable for a destructive test? Capability, Accuracy and Stability - Processes, Machines, etc. 9
S Capability or Gage R&R Study for Leak Tester? Reliability Analysis - Predictions, Testing and Standards 15
D Pre-Production Capability Assesment Reliability Analysis - Predictions, Testing and Standards 5
T Iec 60601 Impedance and current-carrying capability IEC 60601 - Medical Electrical Equipment Safety Standards Series 1
S Machine Setup for a CNC Machine Capability Study Capability, Accuracy and Stability - Processes, Machines, etc. 1
M Measuring Capability of Process with Multiple Specifications Capability, Accuracy and Stability - Processes, Machines, etc. 6
G Capability Study for Tapped Hole Reliability Analysis - Predictions, Testing and Standards 3
L How to evaluate the process capability of a data set that is non-normal (cannot be transformed and does not fit any known distribution)? Capability, Accuracy and Stability - Processes, Machines, etc. 12
T Final process capability results - What I am supposed to present? Cp and CpK? APQP and PPAP 11
G Plotting capability study data - I have a bimodular data distribution Capability, Accuracy and Stability - Processes, Machines, etc. 4
A Statistic Tools to Know Capability of Sealing Machine for Seal Width Capability, Accuracy and Stability - Processes, Machines, etc. 3
Q How to perform Process Capability for true position Statistical Analysis Tools, Techniques and SPC 10
V Generic requirements regarding capability study in automotive Capability, Accuracy and Stability - Processes, Machines, etc. 1
A Capability Analysis for Packaging Seal Strength with spec. >0.1 Kgf using Minitab Using Minitab Software 6
J Initial capability for injection molding part Capability, Accuracy and Stability - Processes, Machines, etc. 6
Ron Rompen Ford Method - Position Capability with MMC Modifier Capability, Accuracy and Stability - Processes, Machines, etc. 14
O Capability or Gage R&R Study for Leak Tester Reliability Analysis - Predictions, Testing and Standards 11
S Understanding control chart and measurement capability Statistical Analysis Tools, Techniques and SPC 2
L IATF 16949 Cl. 8.3.3.2 Manufacturing process design input - Process capability IATF 16949 - Automotive Quality Systems Standard 1
B Short term vs Long term Capability - We ship millions of parts in a year Capability, Accuracy and Stability - Processes, Machines, etc. 7

Similar threads

Top Bottom