Process changes

M

Martin

I had a question: I have difficulty with the fact what exactly a process change (4.9.5.) is. I will give an example. If our operators change the setting of the machinery I think it's a process change, but if we have to register every time that happens the paperwork isn't "funny" anymore. Can somebody give me a good explanation of process change?

Thanks in advance,
Martin
 

Marc

Fully vaccinated are you?
Leader
Is this in regard to resubmission of PPAP to address an 'official' process change?
 
M

Martin

It isn´t regard to resubmission, because I get that, but it´s regard to point 4.9.5. Which states the following:
The supplier shall maintain records of process change effective dates. (see 4.5.3.)
Note: Changes to promote continuous improvement are encouraged. Consult the customer for guidance on approval requirements for such changes.

And I don´t know how I must see the process changes in this case. The same as with the PPAP submission. Maybe you could tell me...

Thanx anyway,
Martin
 

Marc

Fully vaccinated are you?
Leader
If you change a stated process parameter it is a process change. If you change a set-up procedure, a control plan (one or more items) or other process particular, you are changing the process. Typically this is a non-issue as the documents are controlled and as such a history of changes is found in the documents themselves. Most companies look to their Engineering Change System as the repository of a history of process changes and their implementation dates/times. An important factor is looking at this with regard to traceability as well.

What requires resubmission of PPAP is variable and has been discussed in a number of threads here. Do a Search here (maybe for 'resubmit' or PPAP). If you don't find anything, come back to this thread and let me know. I'll help out from there. OK?
 
M

Martin

OK.. I get it, so I don´t have to document every change that my operators make when the change the parameters am I right? Because the way I see it now is that you have a total process change (changing set up instructions, process flow, etc.) or part process change (changing parameters)....

Thanx, Martin
 

Marc

Fully vaccinated are you?
Leader
You have a lathe operation. You notice that you are getting a 'trail' on your piece. Your inspection shows that although this 'trail' is visible, the part passes your surface roughness requirement. You slow down feed rate 10% from set-up and the problem worsens. The operator increases the feed rate 20% from set-up and the problem goes away. The responsible engineer changes the CNC set-up program to reflect this 20% increase. Is this a process change? I wouldn't classify it as such but you can get an arguement that it is. It really has no effect on the product - it was passing (technically) prior to the change and the change of a feed rate is not (opinion on word choice) significant.

You have to make some decisions on a case by case basis what is 'significant' to your process.

Where operators can make adjustments they are typically 'minor' - you want an engineer involved if a 'major' problem arises. Where the operators are 'tuning', they are not really changing the process. In the lathe example operators are allowed to adjust feed rate +/- 30% from set-up. They do not have to get authorization to do this. However - it is expected that the responsible engineer (or other 'authority') be (in general) monitoring what is going on so that s/he knows if every operator on every shift is always setting the feed rate up 20%. The operators are not, however, required to record the change unless it is in response to an out-of-control condition where it is recorded on the control chart.

However, if you change the set-up instruction it technically becomes a process change, but is it significant? Not in my opinion. I don't believe 4.9.5 is meant to control this type of minor process change. I see 4.9.5 as important in more 'significant' process changes such as a change from a grind to a hone, a large process parameter change (such as mold temperature or hold time in injection molding) or a sequence change.

[This message has been edited by Marc Smith (edited 23 May 2000).]
 
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