ISO 9001 requirement for SPC (Statistical Process Control)

[PABSR]

Hi everybody!
Does ISO 9001 requires a manufacturer to perform SPC (Statistical Process Control) studies as a way to demonstrate process stability? Could I demonstrate process effectiveness and stability by simply analyzing data (i.e. percent of scraps, percent of returns/rejections?
When must I use SPC including Cpk studies?

 

[AndyN]

Re: ISO 9001 requirement for SPC

Nope! There used to be an allusion to selection appropriate statistical techniques in the previous version of ISO 9001/2.

Are you being asked to do this by anyone (in particular)? Obviously, if you apply SPC to monitor and control a manufacturing process, it is more in line with the principles of defect prevention, on which an effective qms is supposedly based, rather than inspection of parts at the end of the process. So, really counting scrap etc. isn't truly effective, but it is a way to show effectiveness - yield is one way to do this.

Again, who's asking about this?

 

[brahmaiah]

SPC is required in ISO9001 only if it is documented so in your manuals. if a perticuler customer requires SPC as a supply condition it becomes a requirement for his supplies only.Otherwise ISO9001 does not require SPC.

v.j.brahmaiah

 

[bobdoering]

Does ISO 9001 require a manufacturer to perform SPC (Statistical Process Control) studies as a way to demonstrate process stability?

No. But it can be the best way.

Could I demonstrate process effectiveness and stability by simply analyzing data (i.e. percent of scraps, percent of returns/rejections?

Effectiveness and stability? Maybe. Capability? No. But, you can do a capability study - and that does not have to be from a SPC chart specifically.

When must I use SPC including Cpk studies?

When you want to know the baseline variability of a process (Cpk) and have enough information to know when the process is not acting as expected, or when to make an adjustment (SPC). If that information is of no value to you, then you may not want to do SPC and capability studies. To me, no SPC it is like driving with a broken gas gage. You can do it, but would you want to?

What kind of processes are you dealing with? It is impossible to accurately answer questions on SPC, capability and effectiveness correctly without some idea of what processes you are dealing with. Some are straight forward - some are complicated.

 

[Eric ng]

SPC is surely a very powerful and necessary analytical tool for process capability studies and process control. This will be specified under Section: Measurement, Analysis and Improvement of ISO 9001. The 2000 version does don't specifically require you to use SPC.

Eric Ng

 

[PABSR]

Thank you all for your replies. My apologies for the delay in my comments.
We haven't been asked to perform SPC, although some customers have questioned the lack of it to demonstrate process stability. Our products are not high tech and mostly the quality is evaluated on terms of pass/no pass (attributes). One way to demonstrate process stability has been to measure the amount of seconds and scrap (%) daily, weekly and monthly (on different stages of the processes), but I don't know how much value it could add to perform SPC in this kind of processes. Also, I believe that SPC has to come together with a commitment to reformulate or analyse each process, but if top Managment won't allow to make big changes in the processes (even if you'd demonstrate the possible improvement) , then I believe SPC would be mostly a waste of time in this type of organization and with its current Managment.
Thank you all...I will be waiting for your comments!

 

[Randy]

Thank you all for your replies. My apologies for the delay in my comments.
We haven't been asked to perform SPC, although some customers have questioned the lack of it to demonstrate process stability. Our products are not high tech and mostly the quality is evaluated on terms of pass/no pass (attributes). One way to demonstrate process stability has been to measure the amount of seconds and scrap (%) daily, weekly and monthly (on different stages of the processes), but I don't know how much value it could add to perform SPC in this kind of processes. Also, I believe that SPC has to come together with a commitment to reformulate or analyse each process, but if top Managment won't allow to make big changes in the processes (even if you'd demonstrate the possible improvement) , then I believe SPC would be mostly a waste of time in this type of organization and with its current Managment.
Thank you all...I will be waiting for your comments!

It's their time to waste and you get paid to do it, so enjoy. I know it doesn't make sense, but what other choice do you have?

 

[bobdoering]

Thank you all for your replies. My apologies for the delay in my comments.

I am glad you posed your questions to the folks here. I do want to make some notes on your comments:

We haven't been asked to perform SPC, although some customers have questioned the lack of it to demonstrate process stability.

Really, SPC is not something you should have to be "asked" to do, although it seems some folks only consider it when a gun is put to their head. (Well, if that is what it takes...) Anyway, it is simply a tool, similar to a chart recorder, but with statistical limits that tell you either the process is wandering off, or an adjustment is due. If your process does not have those kinds of measureables, or your process offers no adjustment, then SPC is not likely going to help you. But that should be your analysis of the process - not your customer's.

One way to demonstrate process stability has been to measure the amount of seconds and scrap (%) daily, weekly and monthly (on different stages of the processes), but I don't know how much value it could add to perform SPC in this kind of processes.

If you have no scrap, and no risk of scrap leaving your plant in shipments, then SPC may have little to add to your current controls. It may reduce your controls (if done correctly), but that may not be a problem for you.

Also, I believe that SPC has to come together with a commitment to reformulate or analyse each process, but if top Management won't allow to make big changes in the processes (even if you'd demonstrate the possible improvement)...

I do not agree that SPC has to come together with a commitment to reformulate a process. Analyze? Yes. But it is just as good of a tool to maintain the current process. Now 6 sigma will never get off the ground with your management, for sure!

...then I believe SPC would be mostly a waste of time in this type of organization and with its current Management.

Yes...this is not an uncommon problem.