Company changes policy on revisions - is this used by others?

[ET50]

Keeping this simple, our old policy was to use numbered revisions (1,2,3,..) for pre released documents and change to A,B,C... for revisions that were production released.

New policy is to keep pre production the same but to have 2 different types of revisions for Production released documents. It would still follow the A,B,C for revisions that affect form, fit, or function but they now want to have alfa numeric revisions for drawing changes that don't affect form fit or function. As an example a drawing could be A, then B, then C, then C1,then C2, and then D.

Is this a common way of controling documents? It's created some heated debate and like peoples opinion.

 

[MikeHalloran]

I've seen it proposed, and I've seen it not quite work.
The problem arises when some tiny change that _you_ think doesn't affect form fit or function, actually does have an effect that you didn't foresee on someone else's applecart.



Mike Halloran
Pembroke Pines, FL, USA

 

[sam5a1]

We use that method where I work. We had the problems ET50 said until we defined exactly the errors that could be made an alphanumeric revision and enforced it. For us we only allow the alphanumeric revision when changing formats (that only happens every 10-15 years) or when fixing a simple typo such as teh to the--BUT NOT if its in the BOM or notes. Basically we eliminated it's usage.

 

[KENAT]

Given the definition of revision in the ASME stds this is fundamentally wrong. A revision implies fully interchangeable - i.e. you could have a bucket with mixture of parts rev A thru YY and use any of them interchangeably.

If there is any change that affects interchangeability (form, fit, function...) or that just needs to be traced for some other reason then it should be a new part number.

However, this is going by fairly strict adherence to the relevant ASME definitions of revision. Many places fudge it to some extent.

I've never seen what you propose (though we do use combo alphanumeric occasionally for prototypes of changes to released parts).

Posting guidelines faq731-376

http://eng-tips.com/market.cfm?

(probably not aimed specifically at you)
What is Engineering anyway: faq1088-1484​

 

[ET50]

KENAT,

Form, fit function would still get a new part number. What I see as an issue is once a drawing is production released most if not all revisions will be minor, relative to form, fit, function. So why do an Alfa Numeric revision in the middle of strictly Alfa revisions. I see this as getting confusing for all involved, and would rather just continue with the normal Alfa sequence. The problem I'm having is I see no code or ? that says this not possible. it's hard to argue against something if there is no docmentation that says its wrong.

 

[ptruitt]

Bottom line: Just be consistent. Have a policy and follow it. But I don't like the idea, frankly. Neither would Frank. (Frank Watts, that is...) Form, fit, & function are PART number issues, not DOCUMENT revision designation issues in my 'book' and actual Book books.

Peter Truitt
Minnesota

 

[KENAT]

sorry ET50 - that's not what I got from your OP saying "It would still follow the A,B,C for revisions that affect form, fit, or function" so I'm not quite sure why they're even suggesting apha numerics in that case.

There are relevant standards ET50, though they may be a bit brief in some respects. ASME Y14.100 addresses some especially in section 6 (6.6 &6.8 in particular regarding new PN's etc.). Y14.35 is specifically about revisions though not as detailed as one might like.

Posting guidelines faq731-376

http://eng-tips.com/market.cfm?

(probably not aimed specifically at you)
What is Engineering anyway: faq1088-1484​

 

[truckandbus]

My last company used 'none' identifier for revisions where the cnahge 'didn't matter' (correcting spelling mistake, adding missing leader line, etc.) so a vendor could be working with rev B with a spelling mistake on the drawing and another vendor could be working with rev B WITH the 'none' rev showing the spelling corrected.

Worked ok until an engineer makes a 'none' change that does effect the physical part (oops).