i have a part wich is up to rev d. its been completely reddesigned for rev e. i want to leave the rev d drawing alone for ref and make a new drawing. should i make the new drawing rev- since im starting over and put a note saying replaces rev d?
I tend to be in agreement with most folks here.
To help our folks grasp the form/fit/function issue, we have another mental test. If you can toss a copy of every revision of a part along with the new changes all in a bag, shake them up, randomly pull one out and it will bolt into new and existing assemblies, then the new changes gets a rev. If the new changes won't allow this, then it gets a new part number.
We didn't always do it this way and it has caused great amounts of pain, confusion, etc. I can't count the times we have had to "go back" to old stuff that we never imagined we would have need of.
If your process absolutely won't accomodate this and you don't have a PDM system that automatically archives the older rev stuff, then I am in agreement with Wayne and others to Save As Copy, put the old someplace where it is positively identifiable for what it is, and the modify the saved as file and drawing. I would also start at Rev E with a full explanation in the Properties/Summary/Comments section or the design binder of what and why. Make sure it is a self contained explainable history that would make complete sense to someone that has never seen the files before.
A little pain now will make you really happy six months from now.
If the new drawing is representing revision "E" then the drawing should be rev E.
In the revision block just say "REDESIGNED" and depending on your methods at
your company do a save as copy of the new drawing/part combination so you don't
lose any of what you had previously.
This is exactly why PDM was created.
I would personally try to give it a new part number as the part is "completely redesigned". But if not, then I would probably erase all revs and start with rev e, saying that the part was "completely redesigned". That way there is still a clue that the part used to be something else.
Our rule here is if the part has a new form, fit, or function (complete redesign), it gets a new part number. In some cases, we are obsoleting one part number, and starting a new one. In other cases, both designs remain active. In either case, see first rule, new form, fit, function gets a new part #, all other changes, just a rev level change.
For all rev. level changes, unless the revision block is full, we do not start a new drawing.
i just talked to my boss about this and he doesnt want to change the part number because it would have to be changed in too many places such as the accounting software. the way we work here is, this part is an extrusion. it starts as part number htc96, then its cut to length now it is htc96a, then its tumbled so htc96b, then drilled htc96c and so on. the final part number is htc96d. our part numbers are driven by the process. the drawing for this particular part just happened to be at rev d. so i want to start over with a new drawing, should i start at rev e? the new design eliminates a milling operation, so now the part number will only make it up htc96c. are you confused now.
Then I would certainly start it at rev e as otherwise there is no clue that the part used to be something else.
Does this part have configurations? If so that could open up a different can of worms.
Different revisions for different configurations.
The important factor here is that you don't lose any design history once you make the change. Whether you label it rev E, or start again at rev A or even fresh, you need some way to track back to the previous revision. Some way to tie it back to the previous drawing before the design change. Someone, someday, will want to know what the previous rev was, and why it was that way.
thats why i want to leave the rev d alone and make a new drawing, without the features that were removed, its hard to see what was changed. this way we have the old drawing to refer to.
Don't you keep your old revs somewhere? Attached to an ECN?
I might also suggest just copying the old one and storing it. I'm guessing there is already a process for this in your system, as some sort of file management is very important with SolidWorks and similar CAD systems. If this process doesn't exist, you may wish to consider creating it, since you would never want to loss data on old revisions.
Mark's post about form,fit,function is industry standard. Let say you had an angle bracket that was a weldment, but now you are going to use structural steel. As long as the new rev bolts/mounts upto the same assy's in which it was previously used without any modification, it is a rev change. If you can't interchange it in existing assy's, it is a new part, not a rev #.
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