Process changes

M

Martin

#1
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
 
M

Martin

#3
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

Retired Old Goat
Staff member
Admin
#4
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

#5
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

Retired Old Goat
Staff member
Admin
#6
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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