Drawing Lists
Drawing Lists
(OP)
Hi All.
We have a document relating to each assembly and sub-assembly of a product; namely the 'Drawing List'. It simply details the revision of each drawing pertaining to that assembly.
When a drawing (part drawing, circuit diagram, parts list etc.) is revised, the relevant Drawing List is also updated once changes have been incorporated to reflect build standard.
Previously drawing lists have also detailed the revision of sub-assembly drawing lists. As one can imagine, in assemblies with many levels, this causes an undesireable and time-consuming revision roll all the way to the top level.
The Def-Stan we work to now suggests that the revision of sub-assembly drawing lists need not be detailed, but just referenced as 'latest issue' to avoid revision rolling.
To put the above in context with an example; one of our recent developments had been produced to revision A (top level drawing list revision). We have since had a design review and made modifications to a sub-assembly called up on that drawing list; the sub-assembly revision is now B; however, because no drawings on the top level have changed, the top level is still at revision A because the sub-assembly is now only referenced as latest issue. Therefore any more units produced should in theory still be produced to build standard A, though in reality they will be different from the previous units truly produced at build standard A before the design changes.
Of course, one can update the top level drawing list knowing that changes have been incorporated; but this relies on the individual and not the CM system. Previously, a revision was effectively forced - now it seems out of the loop so to speak.
If someone has worked with a system like such, how has one put this into practice and ensured that the drawing list of assemblies does reflect the actual physical unit? Perhaps I am overlooking something or have misunderstood.
We complained about the previous method with the revision rolling, but I am left questioning the practicalities of this new one!
Thanks in advance!
We have a document relating to each assembly and sub-assembly of a product; namely the 'Drawing List'. It simply details the revision of each drawing pertaining to that assembly.
When a drawing (part drawing, circuit diagram, parts list etc.) is revised, the relevant Drawing List is also updated once changes have been incorporated to reflect build standard.
Previously drawing lists have also detailed the revision of sub-assembly drawing lists. As one can imagine, in assemblies with many levels, this causes an undesireable and time-consuming revision roll all the way to the top level.
The Def-Stan we work to now suggests that the revision of sub-assembly drawing lists need not be detailed, but just referenced as 'latest issue' to avoid revision rolling.
To put the above in context with an example; one of our recent developments had been produced to revision A (top level drawing list revision). We have since had a design review and made modifications to a sub-assembly called up on that drawing list; the sub-assembly revision is now B; however, because no drawings on the top level have changed, the top level is still at revision A because the sub-assembly is now only referenced as latest issue. Therefore any more units produced should in theory still be produced to build standard A, though in reality they will be different from the previous units truly produced at build standard A before the design changes.
Of course, one can update the top level drawing list knowing that changes have been incorporated; but this relies on the individual and not the CM system. Previously, a revision was effectively forced - now it seems out of the loop so to speak.
If someone has worked with a system like such, how has one put this into practice and ensured that the drawing list of assemblies does reflect the actual physical unit? Perhaps I am overlooking something or have misunderstood.
We complained about the previous method with the revision rolling, but I am left questioning the practicalities of this new one!
Thanks in advance!
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RE: Drawing Lists
Fundamentally it relies on strict use of true revisions.
A change is only a revision if it is fully backward and forward compatible, i.e. completely interchangeable regardless of revision.
Any change that needs to be tracked for any reason should be a new part number and require a 714/715 form or something like that as I recall.
I can't remember where this is fully defined in the Def Stans or BS standards. In the US it's nicely detailed in ASME Y14.100.
However, people allways tend to play fast and lose, especially in development stages. You really have to be carefull of this to make the 'latest issue' approach work.
By the way, we were using 'latest issue' back 10 years ago or so.
KENAT,
Have you reminded yourself of FAQ731-376: Eng-Tips.com Forum Policies recently, or taken a look at posting policies: http://eng-tips.com/market.cfm?
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: Drawing Lists
Lower level sub assy's did not have drawing lists, only item lists. The drawings were listed on the higher drawing list.
KENAT,
Have you reminded yourself of FAQ731-376: Eng-Tips.com Forum Policies recently, or taken a look at posting policies: http://eng-tips.com/market.cfm?
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: Drawing Lists
RE: Drawing Lists
The Drawing list must be provided for every 'major' assembly and kept up to date.
Also, due to format issues, we could never get a non CAD system to do it properly, might be possible though.
KENAT,
Have you reminded yourself of FAQ731-376: Eng-Tips.com Forum Policies recently, or taken a look at posting policies: http://eng-tips.com/market.cfm?
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: Drawing Lists
Thanks for your input. I expected you to be in on this one right away KENAT; I had gathered from some of your previous posts you have had experience within the UK in Defence.
We have tended to be selective with the latest issue approach prior to my joining the department and only used it for certain documents.
The idea of having drawing lists only for purchased items seems practical and one that I may promote.
Thanks again!
RE: Drawing Lists
However, I mostly worked on airborne stuff for the then ALM IPT. Some of the naval stuff and maybe army stuff may have done things slightly differently, I didn't work them as much. Even different offices in the same service branch had differences.
I can't recall for sure, but I think that on MRI's you did list the rev of the Drawing Lists but I'm really not sure anymore.
KENAT,
Have you reminded yourself of FAQ731-376: Eng-Tips.com Forum Policies recently, or taken a look at posting policies: http://eng-tips.com/market.cfm?
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?