I've used a 10% rule of thumb, i.e., the sum of decrease conveyor speed from 5 FPM to 4.7 FPM (~6%) and increase preheat from 450F to 475F (~5%) > 10% needs to requalify.

Ed Popielarski
Engineering Manager


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-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Douglas Pauls
Sent: Thursday, May 26, 2016 8:00 AM
To: [log in to unmask]
Subject: [TN] How much change is change?

Good morning all,

One of the IPC groups that I am leading is presently wrestling with the issue of minor vs. major change.  Generally along the lines that if you have a baselined or qualified manufacturing process, how much can that process change before it needs to be re-baselined or re-qualified?
Sometimes this is referred to as Level 1 vs. Level 2 change.

So far, every quality documentation system that I have looked at, like AS9100, ISO9000, etc., gets really fuzzy and uses vague terms when you approach this issue.  Most of these documentation systems have change better defined for products, but get extremely fuzzy and extremely vague about manufacturing processes.

This forum has a lot of very smart, very experienced people. How would you differentiate a minor change, which would not impact form fit or function, from a major change, which "could/would" impact form fit or function?

And I want all you lurkers to come out of the woodwork on this one.

Doug Pauls
Principal Materials and Process Engineer Rockwell Collins


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