Tracking the revision separately for part and drawing

[timbochung]

Been thinking about having a two part revision number:
1a, 1b, 2a, 3a, 3b, 3c...etc.

The idea is that minor changes (missing a dimension, adding a comment) can be tracked separately from any part design changes.

If a drawing is sent out and I have forgotten a dimension or the client would like an additional comment. I think it would be valuable to issue a new drawing with a minor rev change rather than a full blown new level - kinda like the Solidworks service packs (sp1.0 , sp1.1, sp2.0..etc)

People who see the different revision don't have to be too alarmed knowing that it is just a minor drawing revision and not a design change.

Any thoughts?

Tim Chung
Mechanical Designer, CSWP+WLDMNTS+SHTMTL

http://www.kinderdesign.ca

 

[StrykerTECH]

I agree with PeterStock, a minor REV to one person may be a major REV to another. That call will have to be subjective and consequently limited to knowledge of the person making that call.
I still feel that no matter what you decide, you still have to outline what will be different between the two processes.
I know from my own experience, a minor revision process can work when implemented in a small company where there aren't many functional areas and people inherently know more about all aspects of the organization. That being said, when you lay out the differences in the process I bet you will find all sorts of holes on how the process could break down. As you fill up the holes you will eventually find yourself right back at the original REV process.

To the comment about what to put on the drawing, I prefer to put as littel description about the REV as possible. I would rather handle that via another document that can be changed and added to by other departments. This makes the drawing more automatic. Most companies I have set processes up for, have likened to the fact that the drawing just cycles the REV based on a PDM system. This keeps manual interaction down and eliminates the possibility of mistakes. Plus no one likes putting REV on a drawing to change the previous REV's description block error of some sort. That is a vicous circle.

StrykerTECH Engineering Staff
Milwaukee, WI

http://www.stryker-tech.com/

 

[drawoh]

StrykerTECH,

When you add information to a document, you have to ask yourself what the end user needs and is authorized to know. An external vendor with tooling or CAM programming needs to know what you have changed on a fabrication drawing.

I regard ECRs as proprietary. I would not let these outside the company. Also, I have seen a lot of drawings marked AS PER ECO such and such. I have pulled out the ECO and found that it has nothing whatsoever to do with the drawing. Maybe your office is better disciplined than mine.

JHG

 

[fcsuper]

Since the ECO is part of the documentation, where I work, it is not considered any more proprietary than the drawing itself. This is a natural state for a system that is ISO based and relies on the PLM to manage and control documents and changes. Other companies have different systems and needs, so may look at them differently.

Matt Lorono
Lorono's SolidWorks Resources & SolidWorks Legion

http://groups.yahoo.com/group/solidworks & http://twitter.com/fcsuper

 

[StrykerTECH]

drawoh,

you make a good point, but ultimately any system is predicated on the people executing it. So if people are not disciplined the system will fail in some aspect as some point. I have seen changes that you couldn't put enough information on the drawing to convey what has changed, in that case an ECO is almost unavoidable. Furthermore, depending on the dynamics of the business, a drawing can last a long time and it becomes impractical tracking its history on the drawing.

StrykerTECH Engineering Staff
Milwaukee, WI

http://www.stryker-tech.com/

 

[drawoh]

fcsuper,

We subcontract all of our fabrication. I assume that my fabrication drawings are public information. There is no telling where they will wind up, even if the fabricator signs an NDA. All it takes is for a worker to take a drawing home to show an nephew who is interested in becoming a CAD operator.

The ECO and/or the revision block ought to state something like "DIM 1.650 CHANGED TO 1.660". This is harmless, even in the hands of a competitor, or Mahmoud Ahmadinejad, or Michael Moore, or Brittney Spears.

A well written ECR could state that an undersized plug is a safety hazard, and/or provide a detailed explanation of how your stuff works (or not). Your outside vendor only needs to know the change on the part.

Even if you do your fabrication in-house, are you sure the drawing will not be sub-contracted, later?

JHG

 

[djw2k3]

Great Thread.

Ask any software maker and they will tell you its absolutley necessary to have minor revisions and almost all have adopted it - from internet explorer I am viewing in his page 8.0.7600.16385

We have a number of geographical sites so pre-production, whilst designs are being reviewed via pdf, we use numeric revisions on drawings to track production/design comments design which alter the way a part is made. Here the rev table has a ref column for any external references such as ECO XYZ or other

Once its agreed on the drawing is Released at a nice clean Rev A (alphabetical) and the older development pdf say Rev 13 is filed away in the components design history. We generally save up minor changes to drawings and correct missing dims at the end of a production cycle if not important. If however we are asked by a suppplier we will up rev for anything no matter how minor.

This was an attempt to keep track of the numerous design changes in the cycle and promoted the designers not to be afraid of releasing as many drawings for review as necessary & the option of using a single document to track design process.

I believe having an ISSUE # box on tile block also another method. But as somone alluded to this can get confusing as you will have release 2.A for example (Issue 2, rev A).

It suits us for what we do but as this discussion comes up so very often the world is a big place & everyone has a system that suites them - KISS.

 

[macduff]

Wow, this is good stuff guys and gals. The way we do it here is keep the revision of the part the same as the drawing even if there's a simple typo on the drawing. This falls under the KISS philosophy.

Colin Fitzpatrick (aka Macduff)
Mechanical Designer
Solidworks 2010 SP 3.1
Dell 490 XP Pro SP 2
Xeon CPU 3.00 GHz 3.00 GB of RAM
nVida Quadro FX 3450 512 MB
3D Connexion-SpaceExplorer

 

[drawoh]

djw2k3,

Read up on type numbers of American and German aircraft during WWII. They did major and minor revisions.

I think that major and minor revisions are a valid concept at the final product level. At the level of my connector panel, or your C++ file containing one method, all we care about is whether or not something changed. At this level, KISS applies.

JHG