Revision History, when a parts is given a new number 1

[vonsteimel]

Greetings,
I encountered an issue today and I'm wondering how other places handle this.

I have a part that has been used for long time. It has now been significantly revised in such a way that the form, fit & function have changed. Therefore in accordance with our Technical Data System it must get a new number.

So now I have a new part number for basically an "old" part that has a lot of history. Where would I put the details about what has changed? Would I just fill in the revision block as a rev 0? (we use numerical revision designations, not letters).

Other companies just simply do not worry about it? I know the change details could potentially save us a lot of head-scratching down the road.




On another note; When a part is first created, what "revision" would the drawing be on? Is a new drawing a revision 1 drawing -- so that when it gets revised, it becomes a revision 2 drawing? Or is a new drawing considered a revision "0" drawing -- and after the first revision it becomes a revision 1 drawing?

The system we use is the first example. All drawings start at rev 1 level.(actually its a bit more complicated than that) What do others do?
Thanks,

VS

 

[KENAT]

vonsteimel, to ASME stds the deciding factor in whether a change required new part number is basically interchangeability - both backward & forward.

If it is not fully interchangeable then it should be a new part number - but interchangeable can go beyond physical factors see ASME Y14.100 section 6.8.

The release document/ECO/rev block whatever can potentially contain a reference to the old PN to get the history.

As to what the initial rev designation should be, it has been discussed here before.

Initial issue of a drawing does not constitute need for a revision letter and may be incidated by the use of a - (dash).

In practice many places do use 'A' as the initial release (ASME only explicitly lists use of letter revisions).

Posting guidelines faq731-376

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

 

[ctopher]

When you give it a new p/n, you don't list any changes based on its old p/n. It's now considered a new part, no history.
Every company I ever worked at, numerical revs are preliminary, alpha revs are released.
The letter "O" is not used, so I would not use "0". It may get confused with the letter "O".

Chris, CSWA
SolidWorks 14
ctopher's home
SolidWorks Legion

 

[MintJulep]

How do you "release" a new drawing? Does it simply appear, or is there some paperwork involved?

 

[TheTick]

Revision "1" (or "A" or "-"):
"Part released. Formerly part xxxxxx"

 

[Tunalover]

I concur with ctopher. Preproduction designs are given numerical revisions. I think a dash "-" should signify the released part with subsequent revisions given letter designations (except “I”, “O”, “Q”, “S”, “X”, and “Z”) beginning with "A". Once the revision "Y" is reached, then the next revisions are then AA, AB, AC,...BA,BB,BC,... although I've never seen a part get that many revisions.

vonsteimal is correct in saying that any change to the parts form, fit, or function justifies a new part number. Too bad the US automaker (was it GM or Ford?) didn't follow this practice when they changed the design of the highly publicized ignition switch that caused so many accidents and deaths. My understanding was that one engineer changed the form and function of the switch without changing the part number. Everybody downstream didn't think anything of it when they stocked a part under the same part number but a different form and function. After all, the two versions WERE interchangeable!



Tunalover

 

[KENAT]

No Tuna, the parts were mechanically interchangeable, but they weren't truly functionally interchangeable.

Posting guidelines faq731-376

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

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

 

[Tunalover]

Kenat-
That's what I said. I said the parts were interchangeable but did not have the same form and function.


Tunalover

 

[vonsteimel]

So most companies do not track the history as a revision if they give it a new part number... But surely you can see some practical advantage of storing such data, such as why it was changed and what for? Esp in a small/mid-size company where record keeping is not always up to speed. Where do the other companies store such data? Or do they?

From what Tunalover said: "I think a dash "-" should signify the released part with subsequent revisions given letter designations", are most companies tracking both release numbers and rev designations? Where a "release" signifies a minor revision (does not change Form, Fit or Function; i.e. spelling.etc)?

Thanks,

VS

 

[Tunalover]

vonsteimel: What use is there for a "release number". Technically, the revision letter tracks the drawing so if a minor revision were made to, say, fix a spelling error then the revision letter would increase. I've worked in a lot of places and this is how it's done. If there is ANY change to the drawing then the part revision is increased. The drawing revision and part revision are the same thing.

Tunalover

 

[ctopher]

I agree with Tunalover.

On the new drawing, you can add a note "similar to" to ref the old part.

Chris, CSWA
SolidWorks 14
ctopher's home
SolidWorks Legion

 

[KENAT]

Like tuna & Chris say the aSME std's dont cover different levels of 'revision' V 'release' etc. for the same part number. Change to the drawing is a revision, unless it is a change that requires a new part number.

What may change is the approval loop/how many signatories etc. but fundamentally it's still a drawing revision.

As mentioned the ECO/release document for new PN can give a whole bunch of info about the old part if so desired, we sometimes do this were appropriate.

Posting guidelines faq731-376

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

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

 

[Tunalover]

Like KENAT says, the ECN (or whatever the document is called) that releases the new part can (and should) go into detail as to how it was created using the old part as a baseline.

Tunalover

 

[truckandbus]

In similar situations, I've placed a stamp across the old part drawing saying 'not for new designs, superceded by part number XXXXX'. On the new part drawing, I'd make one of the notes read 'supercedes part number XXXX'

I am a huge advocate of the revision block detailing each and every change - too many years of working back revisions to find out why something doesn't work anymore. Otherwise the rev block says 'see ECN" and the ECN says "see rev block"