What is the main advantage of having a separate document for the BOM 1

[tmoxam]

If the bom and the drawing are separate documents it is possible to up rev one document and not the other. if using a PLM/PDM system then only one document needs to be checked out.
the problem is that the revision levels will be different for each document. They will not match and some (customers) may not like that situation. My solution to this is to date the BOM but use a revision level on the drawing. So basically, the latest BOM goes with the latest drawing.
So we know what the "problem" is, so what is the main advantage?
We are defining SOP's and CAD Standards at this time and i would appreciate your input.
Thanx,

Tim Moxam
Senior Mechanical Designer
Aversan Inc.
Toronto,Ontario,Canada

 

[ctopher]

Although could be a pain to keep separate BOM's updated, it's cleaner. You will know which rev of the parts are tracked on the assy. Having it on the drawing, the BOM shows no revs, and the drawing will have to get updated if the BOM changes.

Chris
SolidWorks 11
ctopher's home
SolidWorks Legion

 

[drawoh]

tmoxam,

I am the guy to separated the assembly drawings and BOMs where I work. The problem on the drafting board at the time, and the problem on SolidWorks now is that the BOM takes up valuable space on the drawing that could be taken up by drawing views. We design large, complicated stuff. A BOM with eighty to a hundred items takes up a lot of space. The separate BOM is a functional document on its own, especially if it is in some accessible format like Microsoft Excel.

Our BOM has separate columns for manufacturer, part number and description. This is not a problem in an external BOM. It makes for very inefficient use of space on a drawing. If I had to create an on-drawing BOM format now, the part would be defined by a single description field, possibly restricted to sixty characters. Anything not describable by this would be called up by a company part number pointing to a document with ordering instructions.

Drifting somewhat off topic here, your BOM format should allow you to fill in purchase requisitions by copying and pasting. Your MRP/ERP people should be able to fill in their BOMs by copying and pasting. Making BOMs letter consistent, if not perfect, is fairly easy with 3D[ ]CAD like SolidWorks.

Our CAD manager insists that we put BOMs on the drawing. Our BOM format is awkward, as noted above. Our drawing space is not used intelligently.

On smaller, simpler assemblies, this is not a problem.



--
JHG

 

[CheckerHater]

Sometimes BOM automatically generated by CAD software simply doesn’t tell the whole story.
For example if your product is shipped unassembled (think IKEA ), there are several positions of boxes, bags, stickers, customer assembly instructions, etc., etc. that have to be taken care of.
In order to place order for all of those components, somebody has to create “extended” BOM, which could be separate document.
Naturally every product is unique, so what works for one company may not work for another.

 

[KENAT]

If you work to ASME stds you could take a look at ASMEY 14.34 for some ideas. Even what they call a 'separate parts list generated from digital data' requires a revision.

The system I worked in the UK had separate item lists rather than on the drawing. We also had 'drawing lists' for all top level drawings which listed the rev for every drawing (including item lists). This had its own issues especially as they were done manually (though using CAD). Y14.34 allows for what they call data lists which are similar.

(Minor point, I'm not sure BOM/Bill Of Materials is actually a drawing term. On a drawing it's usualy referred to as a 'parts list' in the US or 'Item List' in the UK as I recall.)

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[MikeHalloran]

One part of product development that can consume a lot of time is figuring out exactly what the shop is actually making, and what they are using to do so.

Having the complete BOM, structured if you wish, sorted any way you like, accessible from any computer, just absolutely beats the hell out of trying to figure out a complex product's anatomy from a pile of prints. Having the prints with embedded BOM in pdf or other electronically viewable form does not substantially speed the process.

Accessing the BOM structure electronically, without images, is much faster, even if you are burdened with a GUI display for text data.

Honestly, I thought a PDM was a bad idea, until I'd had a chance to get used to it.

That doesn't mean that every implementation is perfect. The transactional "smart terminal" based stuff, where you have to acknowledge a "bad" keypress before the system will accept a "good" one, is particularly annoying, and can still be found in outfits that bought their business software around 1972, and have only patched it since then. Any reference to an "AS/400 system" should cause you to leave immediately and forever.



Mike Halloran
Pembroke Pines, FL, USA

 

[CheckerHater]

Good point Mike,
If you treat your BOM like complete description of final product as it goes out of the door, there are more people involved than just a designer, so the BOM should be available/accessible for all of them.
In our company we use CAD-generated BOM as “preliminary” document that is serving as a basis for electronic BOM being later created in PDM-ish system.
Works well so far.