AS9102 Section 5.3 - FAI anytime a machinist tweaks a CNC program?

[tbuk1972]

I would like some advice regarding AS9102 section 5.3, 3. A change in numerical control program or translation to another media that can potentially affect fit, form, or function.

Does this require a partial FAI anytime a machinsit tweaks a CNC program?

[Don Palmer]

In Reply to Parent Post by tbuk1972

I would like some advice regarding AS9102 section 5.3, 3. A change in numerical control program or translation to another media that can potentially affect fit, form, or function.

Does this require a partial FAI anytime a machinsit tweaks a CNC program?

tbuk1972, welcome to the Cove. While waiting for a specific response, you might want to search these forum links.

AS9102 - Do I have to do FAI for all Standard Catalog Hardware items?

Following AS9102 for FAI Requirements - Does EVERY Component Need Its Own FAI?

TL9000 Measurements for PC (product category) 5.3

[Sidney Vianna]

In Reply to Parent Post by tbuk1972

I would like some advice regarding AS9102 section 5.3, 3. A change in numerical control program or translation to another media that can potentially affect fit, form, or function.

Does this require a partial FAI anytime a machinsit tweaks a CNC program?

The safe answer to the question is YES.
Machinists "tweaking" CNC programs can be a very costly proposition, depending on the nature of the changes. Remember, CNC program is DATA that requires control and revisions to such programs need to processed in a controlled manner. It can obviously affect the part's conformance to specs. Obviously, it is dangerous to generalize, but having machinists changing CNC programs willy nilly without proper engineering review can lead to a lot of problems.

[Jim Howe]

I once observed a knowledgeable and experienced CNC programer solve a reported problem on first piece inspection by off setting a tool (in this case a drill bit). It was a simple correction but the programmer forgot that the tool was also used in subsequent operation (drilled more then one hole). Guess what? The offset showed up everytime the program called for that particular tool and since the program was not sent back through first piece again the entire lot (30 radar base castings) had to be scrapped (very expensive and tossed the schedule into the round file).
IMO every change to CNC programming must be reviewed and checked.

[Brian Myers]

In my experience with CNC processes you have two sorts of "tweeks"...

1) Machine Offset - This is something that can be done by the operator, "on the fly", and should be logged. These are most commonly due to tool wear and are often necessary. As with any change in machine or material condition, First Piece Inspections should be done to verify the machine executes all processes within specification after the offset adjustment. This too should be logged by the operator.

2) Program Changes - these include tool offsets, tool path adjustments, and any other change to the program or specific tools. These should only be done by Qualified Maintainence or Engineering and would require a more formal and thorough trial to prove stability.

Just my 2 pennies...

Brian

[al40]

HI,
Speaking from my personal experience we had a CNC programmer make a change to a CNC program and a FAI was not done. The programmer felt the change was insignificant and did not affect fit, form, or function but when he changed the coordinate in the program it threw off some of the mounting holes on the product.

The parts made it through final QC and to the customer who found that none of the holes matched up to his aircraft. We had by this time ran and shipped 30 more parts before we found out we had a problem.

We then had to host on site audits and six months worth of source inspections because we failed to perform an FAI on a minor change.

So to make a long story short do the work up front and it will pay off in the long run. We now require an FAI on all CNC program changes regardless how simple the change was.

Remember "an ounce of prevention is worth a pound of cure".


Best of luck,

Al

[tbuk1972]

Thanks for the input!