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11-21-2010, 07:00 PM #1
First piece ( NOT 1st ARticle ) - Procedure
Guys, just want to ask a question about your First Piece Inspection procedure.
First off, this question refers to First Piece and not First article inspection, meaning that this inspection is done at each and every step ( operation ) of the manufacturing process of a part, starting from receiving of material and ending at final deburr/cleaning.
It cares not about the final fit, form or function of the component, rather it cares about the actual operation at hand.
So. My question is this: How do you handle this step and how is it submitted?
Here is my take on this. The 1st piece inspection is in place to verify all the manufacturing steps up-to and including the current operation.
That is to verify the process engineer, programmer, setup person, machinetool, cutting tool and in-process ( shopfloor) inspection equipment at this exact state of the component.
Up to now, all of my major customers have handled 1st piece insp. in a way that as soon as the first part comes off the machine ( assuming no disaster has occurred ) the part is first inspected by the setup person ( or operator as it may be ), measurements recorded and the results are submitted along with the part to a dedicated first piece inspector. Here is the key: There are no adjustments made by the setup person/operator to the part, program or any other equipment, no second part machined to verify the changes. Nothing. The first part is in fact exactly that: First piece.
The first piece inspector now completely inspect the part up-to this stage and does so independently. His results are then compared to the results from the setup/operator person, discrepancies are determined and evaluated, necessary corrective actions are taken and then part operation is either released for production OR a new first piece inspection requirement is determined.
Well, just got into a discussion with another jobshop guy from here ( not customer, just a fellow machineshop owner ) who insists that all of his customers require a dimensionally correct part as first piece at each and every single step!
To me this makes absolutely no sense, here is why.
We all know that there are a great deal of possibilities where mistakes can be made. Process engineer can make mistake in interpreting drawing, creating wrong opsheet. Programmer can make mistake and create dimensionally correct part program but neglecting the leftover stock for a future operation. Setup/operator can make a mistake and incorrectly interpret a feature, incorrectly inspect the feature or use inspection equipment that is ( for whatever reason ) out of tolerance or inadequate for the measurement.
Anyhow, the bottom line is whatever the mistake is, it will likely be repeated again and again, thereby producing wasted material and wasted time, all without any chance of improving the process.
What say you? What is the procedure you guys use either internally or with your outside customers? Again, this IS NOT a FIRST ARTICLE!!! question.
11-21-2010, 07:11 PM #2
In our operation, the set-up person is responsible for getting a good part off the machine before any further detail inspection is performed. Detail inspection is a finite resource, and you don't take up their time with bad parts anymore than you absolutely have to.
Not all features are measurable by the set-up personnel, those features have to be sent to the inspection lab, but everything else is good before they send it up.
All set-ups and gauging are verified and signed off by both the set-up person and the shift supervisor (including detail inspection results) before production is released.
11-21-2010, 07:18 PM #3
I agree with everything you wrote... and that's the way I did things in my shop.
One main reason to not submit first pc inspection to the customer was my customer was the Govment, and all they wanted was finished parts, assembies, or in some cases the FA so they could check it before allowing or starting the rest of the contract... I'm hesitating now over my ise of the word allowing... they have little or no say at all when I made the stuff. BUT, spose they found something wrong and I made all the contract, I might be up the creek with a buncha bad parts.
Is it common practice these days for a customer to approve the results of each setup?
They'd get charged a bunch for that in my opinion.
11-21-2010, 09:00 PM #4
My parts are usually of a rather expensive material. Inco and TI, sometimes goes as much as $100+ for material alone.
In addition, a good amount of my work is one or two operation on a part that already has seen quite a few operations and processes, meaning it already has quite a bit of value ( either material or labor/machine time).
Believe me, the inspector's time is typically less than lunch money when compared to the part itself.
If I make the part complete, then they may only want a first article, but as I've said above, often I'm only tasked with one or two ops ( usually EDM ) for an already machined part, in which case it is I who insist on a first piece check. I'm completely independent and responsible for each and every thing I do from drawing, process, program, setup, run, inspect ....
11-22-2010, 05:00 AM #5
The last shop I contrated to (major medical company) had thier traveler set up in a way that had the first line for set-up part good/bad...then first piece 100% insection by machininst...next was part run demension...So you could track your materail and sizes for each run of part...This was after part validation that would cover the process engineer, programmer, setup person, machinetool, cutting tool and in-process ( shopfloor) inspection equipment...
So the term 1st piece can mean a few differnce thing to people like... Is it the 1st pice of a new job befor validation...is it the 1st piece (set-up) of a unproven run after validation...is it the 1st peice of a proven run (after 1st run and validation) or is it the 1st piece after a crash durning a run....
11-22-2010, 05:08 AM #6