8.5.1.1 Control of Equipment, Tools, and Software Programs - Questions about the extent of control of NC programs

CanadianQA

Involved In Discussions
Hi Everyone,

My company is AS9100 certified. Part of our operation is a small machine shop. I have questions about what software needs to be controlled and validated, to what extent and what constitutes validation of NC programs that are input into our 5 axis CNC milling machine.

As far as I understand, the machinist either gets a CAD or Inventor drawing and re-draws the part as a feature cam file. Alternately, he will get a STEP file that is then translated into a feature cam file. The feature cam file is what is actually fed into the machine to control the machining process. According to the production team, the machinist will make tweaks to the feature cam file. This will include feed rates, different cutters, cutter path, etc... The end result is the same, it just takes a bit of time to get the file set up so that it makes the part in the most efficient way.

Ok, so now for the questions:

1. How much and what type of control is required for STEP or feature cam files? Should the machinist be tweaking these files as he goes?
2. What constitutes verification of these files? Up until now, we have been using the inspection of the product to verify the output of the software. If the product passes inspection, then the file is verified. What records should we be keeping to show evidence of verification of these feature cam files?
3. Does the feature cam file need to be re-verified every time that the machinist makes a tweak?

Any thoughts would be appreciated. Thank you.
 

Kronos147

Trusted Information Resource
One way to validate the program is to have the first part inspected.

It gets more complex if you desire to have each operation verified. In this case, there needs to be agreement as to what was established in each op (what should be inspected). If you leave a feature 'big' as it will get 'smaller' in another operation, is an example of this scenario. Our shop, we also realize at times things are slightly lower than spec, to allow for paint. We put those requirements in the work order\traveler.

In terms of the file control, that's a tough one to advise. What do you do now? How effective is it?

Recently, we had a machinist make something bigger because he 'thought' there was another process that made it smaller later. We do, but on a like part, not on that one. We had to remind him to check the traveler.

It was discovered during the first piece inspection, so, the program was 'unmodified' and run again with a new setup piece. Then, another inspection.
 

CanadianQA

Involved In Discussions
Yes, we do "First Off" inspections that validate the program changes, however they are not recorded anywhere. This is somewhat part of the art of machining. I don't see that AS9100 requires that we record this... At this point we have no requirement to control the machining process down to each machining operation.

What we currently have in place is that our engineering dept. controls and verifies our STEP / CAD / Inventor files. These files are then passed to the machinist who then creates the feature cam file based on the file from engineering. CAD / Inventor files are usually just very simple parts. The machinist will manually "draw" the part in feature cam. STEP files are for the more complex parts and the feature cam program just takes the file, does it's magic and converts it. The machinist keeps these files on our server marked with the part number of the part and revision level of the drawing so that it can be used again for the same drawing rev. This has been the way the system has worked for the last 10 years and we have had no issues that I am aware of.
 

CanadianQA

Involved In Discussions
It is EXPLICITLY required in 8.5.1.3 - The organization shall retain documented information on the results of production process verification. Could not be clearer.

Yes, agreed. Sorry, my last comment was specific to validating changes to the feature cam files, not the production process as a whole. These files can be changed several times during one production run until the best balance of quality / cost is obtained, so it seems that it is not practical to keep records of validation of each change.
 

Big Jim

Admin
It is EXPLICITLY required in 8.5.1.3 - The organization shall retain documented information on the results of production process verification. Could not be clearer.

Perhaps it is time to talk about the difference between verification and validation. Verification records are required. Does that include validation records? Maybe it is not so clear.
 
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