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Revision schemes

Question asked by Joel Tutman on Jan 26, 2012
Latest reply on Mar 8, 2012 by Brian Dalton

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Hi all,

I am struggling with setting up a 2 level (Major/minor) revision system in EPDM. I would appreciate some feedback on the proposal bellow.

We have narrowed our options to the following:

Option 1 - Major/minor revisions are tracked in meta data.

Minor revisions for: correcting drawing typos, and part changes that maintain interchangeability.

i.e if a revised part can be intermingled in production inventory with previous iterations of that part without any negative effect then minor revision is appropriate.

Major revisions for: changes that render the parts non interchangeable.

Revision Scheme: Major- A, B,C,D Minor : 01, 02, 03, 04

Major and minor revisions will only show in meta Data and will not be included in part number.

Note: For both options both drawings and models will have the same PN and revision.

Option 2 - Major revisions change the PN, only minor revision are tracked in Meta data.

Minor revisions: same as in option 1 and tracked on data card.

Major revisions: Changes that render the parts non interchangeable will trigger a PN change.

The part number will be a change to a dash number (very last character in PN). e.g 300-12345A

300-12345B OR a complete change to a PN.

For option #2, Only minor revisions will be tracked in Meta data.

Questions to group:

- Are there any users out there who can report a successful workflow for tracking two types of revisions.

- Which of the above two systems is preferred?

Thanks

Joel T

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13 Replies

Ian MacPherson Jan 26, 2012 8:48 PM
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Joel, we are using option 2. Our dash no. is an editable variable on the data card and automatically appends to the document number (we have it setup to be the same as the file name) to form the part number.

We are using the PDM to increment "revisions" in files, alpha for drawings and a numerical for the part/assembly files, but for the part and assembly files it does not relate in any way to the dash no. or the drawing revision. We don't even have it linked to a variable, on the data card we call it change level and it simply means the amount of times it has been transitioned into the released state. This is mainly to have the functionality to only allow certain users/groups to only see "revisions" and not "working versions" (versions that are not revisions).

We did look at using the PDM to handle the incrementing of dash numbers in files, but the workflows quickly became too complicated so we left it as a manual process.
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Howard Dexter Mar 7, 2012 11:04 AM
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Joel, I'd never add a "revision" to a part number. Doing so creates a new (unique) part number which, to me, says the part is no longer interchangeable with the prior iteration. Just my 2 cents.
Revision = interchangeable; Unique PN (incl. using a dash no.) = non-interchangeable
I've set up our revisions to start with "X1" prior to release (numeric minor revision)...users can increment to X2, X3... manually as they see fit.
At release, the revision advances to "A" (alpha major revision). To revise after release, a state change is required before checkout is allowed. The change state advances the revision to "A1" (major/minor) and can again be manually advanced to A2, A3, etc.
At revision release, advance to B (major).
We also use dash numbering freely to create unique numbers for non-interchangeable "variants" of existing items. Like you, we do that manually.
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- Brian Dalton @ Howard Dexter on Mar 7, 2012 11:32 AM
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  If you create a new part number for a non-interchangeable change you lose direct traceability because you start a new history for the new file. If you use a Major/Minor change scheme, you can contain both interchangeable and non-interchangeable changes in one file, thereby maintaining one continuous file history.
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  - Howard Dexter @ Brian Dalton on Mar 7, 2012 11:57 AM
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    Great point, Brian.
    I'll have to consider that for a while, though.
    Off hand, I can't think of why I would need the history of more than one part in a single file.
    Thanks!
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    - Brian Dalton @ Howard Dexter on Mar 7, 2012 3:56 PM
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      It depends on whether you consider it a different part. If a shaft is revised to allow a different fit into its assembly, it would certainly no longer be interchangeable with the earlier version, because of the change in performance/functionality. It would not be a completely different part, though, just an updated iteration of the same part. It would seem reasonable to want to have easy access to the history of that part; the earlier designs, the logic behind the changes, etc. At least that's how our Engineering department sees it. They are adamant about wanting as much design history as possible available as easily as possible.
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      - Lee CS Young @ Brian Dalton on Mar 8, 2012 9:13 AM
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        History is maintained in EPDM when renaming files.
        
        IMHO: Form, fit and function changes warrant a new part number. If an assembly can't use the old 'revision', it's not the same part.
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        Brian Dalton @ Lee CS Young on Mar 8, 2012 10:38 AM
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        Lee CS Young wrote:
        
        History is maintained in EPDM when renaming files.
        
        Just to be clear, what you say is true if the file is merely renamed, but what I understand that we're talking about is creating a new file - with a new part number - based on the original file. This would be done via Save As or similar process.
        
        The problem with just renaming a file to a new part number is that any legacy assemblies that refer to that file now have broken links. In a company that enforces a strict policy wherein every part change causes the obsoletion of the previous part in all assemblies where it's used, this concern would not exist, but in a case where previous revisions remained active, it would be necessary to keep the previous part number, hence the value of using major/minor revisions to maintain a continuous part history.
        
        There are many possible philosophies that can drive change and tracking schema. Every single company I've ever worked for had a different take on these issues...
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        Howard Dexter @ Brian Dalton on Mar 8, 2012 11:16 AM
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        I hear you, Brian. Even with numerous configuration management standards available (ANSI/ASME and others), many companies attempt to reinvent schemas either naively, or in order to resolve some unusual requirement. We have differences like this *within* our company from one division to another!
        
        In the case of "save as", it would be great if EPDM history would mark that event in the file history...other systems I've used do.
        While I really like EPDM, there are also other areas where I'd like to see more/better history capture.
        
        Just to throw out some thoughts on your shaft example...what happens when/if you want to reuse the original version? Do you have to roll back the file, redo the version? We often use dash numbered configurations that share a single tabulated drawing for cases like your shaft. Everything can be captured in a single file, uniquely numbered as non-interchangeable, early parts can be reused easily, and history will capture the progress of the part.
        
        Just another 2 cents. You and I would probably both do a lot of things differently if we made the rules in our company!
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        Brian Dalton @ Howard Dexter on Mar 8, 2012 11:44 AM
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        Howard Dexter wrote:
        
        In the case of "save as", it would be great if EPDM history would mark that event in the file history...other systems I've used do. While I really like EPDM, there are also other areas where I'd like to see more/better history capture.
        
        Yes, I think we would all like to have a shot at the 'next feature to be implemented list!
        
        Just to throw out some thoughts on your shaft example...what happens when/if you want to reuse the original version? Do you have to roll back the file, redo the version?
        
        By keeping earlier revisions active, any assembly created is at liberty to use any major revision they choose. Major revisions must be treated like separate part numbers on the BOM and in inventory, so the difference between using Major Revs and new P/Ns is purely the ability to maintain continuous part history.
        
        We often use dash numbered configurations that share a single tabulated drawing for cases like your shaft. Everything can be captured in a single file, uniquely numbered as non-interchangeable, early parts can be reused easily, and history will capture the progress of the part.
        
        This is a very interesting concept, and a bit of a different wrinkle in the issue. The only uncertainty I see right off is that when a part is up-revved, all configurations are simultaneously up-revved, so this may have larger consequences if revisions are significant (i.e. non-interchangeable, needing to be tracked). Otherwise, I can see how it would work.
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        Wayne Matus @ Brian Dalton on Mar 8, 2012 11:18 AM
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        You can add a couple of fields on the data cards, "Supersedes" and "Superseded By" to link the history between the files.
        
        With your companies method, how do you handle inventory when the same part number at different revisions are not interchangeable?
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        Brian Dalton @ Wayne Matus on Mar 8, 2012 11:48 AM
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        Wayne, I've used this method a bit, but the problem is that when you create a superseding part, you must change the 'Superseded By' variable on the earlier part, which generates a new version. Doing so causes any file that references it to be referencing an out of date version, and also the 'revision stamp' in the file history is on the version prior, which does not have the 'Superseded By' variable set. Our Mfg people have access only to released revisions, so they would not see the 'Superseded By' value at all.
        
        This could be solved if it was possible to set/change a variable without creating a new version, but that's not possible in EPDM.
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        Brian Dalton @ Wayne Matus on Mar 8, 2012 11:51 AM
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        When a part number has more than one revision but they are not interchangeable and they all need to remain active, they must all be marked with P/N-rev and kept in separate bins as separate inventory items. They are in essence different parts, but they share the base part number to retain continuous file change history.
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Wayne Matus Mar 7, 2012 12:04 PM
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I have used a combination of the two methods to handle when you want to make improvements to a part, but its does not affect interchangeability.

Minor Revision: 01, 02 etc - Correcting drawing mistakes such as typos. Do not need to stop current production of parts.

Major Revision: A, B, etc - Affects manufacturing but not interchangeability. You want to stop production until the change is processed.

New Part Number when change affects interchangeability.
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