Bill Of Material Standard for Drawings 4

[JASON8102]

Lets try this thread I started a different way by breaking it down better. Forget about ANSI and ASME standards for a min. How many engineers if making a drawing of a part with 2 weldstuds, or pemnuts, ect...some type of permanent hardware to the part don't use a bill of material on their drawing, you just leader line out a note on what needs to be installed or welded? I understand you use a bill of material if you MAKE it in house, but we don't. We don't stock pemnuts,weldstuds, weldnuts, ect...So my standard would read,"A bill of matieral is only needed on a print, if it is a weldment,a physical assembly we build, or it's an assemlby that can be dismanttled easily into loose items." Thoughts?

Jason Schultz
Mechanical Engineer
Yaskawa Electric America
"It's got to be 5pm somewhere!"

 

[KENAT]

I'd disagree. If it's an assembly it's an assembly. Add the parts list. For most CAD systems these days this doesn't take a whole bunch of effort, possibly less than call-outs to each part depending how you do it.

We used to have drawings of inseparable assy's and the like with just callouts to the parts. Things would get missed or there'd be questions.

Most of our inseperable assy work is also done externally like you and this system seems more robust. We don't stock the pem studs etc.

Then again, we took the decision to follow ASME standards some time ago, so forgetting them isn't really an option.

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[JASON8102]

KENAT- to then follow those great standards that have been written, there should be a "Part number" in the BOM format, we then need to "make-up" basically part numbers for stuff that we don't need to, and maintain yet another data base for that. Not efficent.

Jason Schultz
Mechanical Engineer
Yaskawa Electric America
"It's got to be 5pm somewhere!"

 

[MadMango]

I tend to agree with KENAT. If you always use a Parts List on the Drawing then there is no need to remember Rules. KISS.

"Art without engineering is dreaming; Engineering without art is calculating."

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[ewh]

If it is an assembly, in needs a parts list (separable or inseparable). Procument should not have to examine every drawing closely to determine if multiple components are involved, and items may be easy to miss especially, using your example, if several different size PEM nuts are used. Not using parts lists for every assembly is allowing for unnecessay mistakes to be made.
In your example, why are weldments different than an assembly using PEM nuts? Both are inseparable, aren't they?

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[MadMango]

You don't have to use a Part Number in the Parts List, you could just use good Descriptions. But if they are components that you are continually using, I don't see why these components can't be in your existing "database" with part numbers.

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[JASON8102]

welments contain specific parts and/or drawings to build. Like the weldment of an enclosure there is a top,bottom, LH, and RH sides....a bom would be required here. However if I have flat stock with 2 weldnuts in it I'm saying why do I have to make a BOM with the weldnut part numbers. Add a simple note "1/4-20 WELDNUTS" with the proper welding symbol I need. Procurment has nothing to do with this. The vendor / sheet metal place that gets our print to make this will make their own BOM and routing from our print anyways.

Jason Schultz
Mechanical Engineer
Yaskawa Electric America
"It's got to be 5pm somewhere!"

 

[ewh]

we then need to "make-up" basically part numbers for stuff that we don't need to

???

Components in weldments can easily be identified with dash numbers. They should be identified in some manner, regardless.
Other items such as hardware usually have a vendor number if nothing else.
Numbers are cheap, and I find your reasoning for not creating them somewhat baffling. How are your receiving and purchasing departments set up?
If you plan on remaining a very small company that can reliably use tribal knowledge indefinitely, then no problem. Otherwise, it is time to smell the coffee.

"Good to know you got shoes to wear when you find the floor." - [small]Robert Hunter[/small]

 

[ewh]

Again, refering to your weldment example... why do you need a BOM for weldment details and not other components? Can't you just call them out on the FOD as you do weld nuts? Why not?

"Good to know you got shoes to wear when you find the floor." - [small]Robert Hunter[/small]

 

[JASON8102]

Yaskawa is far from a small company. Japan where our corporate office is, does this type of drawing as well....weldnuts will just be noted on the print, no BOM on the drawing. What we recieve in is the completed item form the vendor. We don't recieve pemnuts or weldnuts or permanent hardware for that matter. If the weldnut falls of during installation, we send the whole thing back to the vendor for a new one to be welded.

Jason Schultz
Mechanical Engineer
Yaskawa Electric America
"It's got to be 5pm somewhere!"

 

[ewh]

It looks as if you are sending out conceptual designs for vendors to complete and build to. Formal, complete drawing packages may not be necessary for this type of purpose. Just document what you want to see, and enforce that standard. We don't have to agree with what you finally come up with. I would caution you however against referring back to established industry standards unless you are sure that you can follow them and have all exceptions to those standards documented.

"Good to know you got shoes to wear when you find the floor." - [small]Robert Hunter[/small]

 

[JASON8102]

Well the post started off as who does this and doesn't. So far I have 4 people that have said they would use a BOM. The way I have described I know isn't wrong, I have been doing this for 15+ years. I have done it both ways. I AGREE, that if I was the one manufacturing a flat bar stock with (2) weldnuts in it, I would need a proper BOM on the print so it can be cost rolled up and routings created as well.

Jason Schultz
Mechanical Engineer
Yaskawa Electric America
"It's got to be 5pm somewhere!"

 

[MadMango]

So I'm still a bit confused, are you now talking about Purchased vs Manufactured parts? If you are receiving "completed parts from a vendor" then I think you'd be using some flavor of Source Control Drawings, and then you would not need a Parts List. Sorry I missed that.

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[JASON8102]

MadMango- I am talking about purchased vs. manufactured. We don't manufacture parts, we engineer them and buy them. We use SAP, we do control our documents in there and materials. HOWEVER, I don't control weldstuds, pemnuts, ect that are used by the vendor to make my parts. I think you and I are on the same page here.....ya?

Jason Schultz
Mechanical Engineer
Yaskawa Electric America
"It's got to be 5pm somewhere!"

 

[drawoh]

JASON8102,

I make a distinction between a parts list which we use to order our parts, and a material list, which we apply to fabrication drawings that are sent out to a vendor. The vendor orders the pieces on the material list and attaches them to whatever they are fabricating. We order and stock the stuff on the parts list.

Both parts list and material list are implented using SolidWorks' BOM feature.

The most important thing you can do on your parts list is make sure your data is set up in the same format as your purchasing requisitions and your MRP/ERP database. You should be able to copy and paste out of your parts list and onto your requisition form. Information should be typed once, only.

JHG

 

[JASON8102]

Ok here's an example of what I'm talking about. I'm saying there's no reason for a BOM on this print. Item 1 would be obvious, item 2 would be the pemnuts of course. In the title block we give material to made from, but I have deleted the title block from the picture. We send this out to be made and we recieve it as 1 part not 2 parts.

Jason Schultz
Mechanical Engineer
Yaskawa Electric America
"It's got to be 5pm somewhere!"

 

[KENAT]

So firstly, from a drawing point of view you don't have to assign them your own unique part number. Use a vendor/manufacturer part number, using an MS or similar might be even better. For instance, you could use something like the McMaster Carr part number or a similar catalogue. You could qualify this with an 'or equivalent' statement, though there may be some risk.

It's surprising how many descriptions used are actually incomplete or open to misinterpretation. Referring to a specific vendor/manufacturer & part number significantly reduces this likelihood.

We're actually gradually updating a lot of our assy drawings to add more 'manufacturer part numbers' for even fairly standard fasteners, since descriptions alone are sometimes unclear to our offshore vendors.

We don't typically create a BOM in SAP for our inseparable assemblies, we treat them as we would simple parts. However, the drawings have a parts list with the pem studs or whatever as well as the basic sheet metal or machined part. Due to limitations of our SAP implementation, our CAD package and our established doc control system, we fudge a few aspects but it seems to work.

When outsourcing (be it domestic or foreign) it’s even more important that the drawing is unambiguous and easily understood, following established standards really helps with this.

I’ve never seen a really good Japanese drawing, they’ve always been a bit lacking. Now clearly this hasn’t held them back much, but unless you’re also copying whatever else they do that makes it work for them, I’d be careful.

Also, I learnt, and occasionally have to relearn, just because I’ve done something a certain way before and apparently got away with it, doesn’t necessarily mean it was the right way.

MadMango, if the OP is creating the fully detailed drawings, and just outsourcing the actual manufacture, then a Source Control probably isn't appropriate. We outsource most of the inseparable assy type work and some assembly work, we experimented with expanded use of Source Control drawings but it didn’t' work out. Conventional assy drawings do seem to work, you just need to make sure all items are adequately identified that anyone can go buy them without access to your ERP system.

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[ewh]

Forget about ANSI and ASME standards for a min.

I'm not sure what you are asking for, then. As they say, opinions are like a******s, every body has one.
Drawing standards are just that, standards. If we are to forget about what they say, then you can pretty much do whatever you want.

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[KENAT]

Jason, you were typing while I was. I tink I completely understand what you're saying, we do similar. That doesn't change my opinion that based on my own experience as well as what the standards say, that using a parts list is probably the way to go.

On your sample for instance, you don't really fully define the pem nuts. From memory aren't there different material options, even maybe lengths etc. Obviously you don't have to have a parts list to add the part number, but to me it's a tidier way to do it than with the callouts.

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[JASON8102]

EWH- The problem with "standards" is that they don't get updated as new technology comes into play! Some of the ANSI standards still talk about drawing in layers, line types, line weights ect......well if you are still in those dark ages then ya, live and die by those standards I guess.

Jason Schultz
Mechanical Engineer
Yaskawa Electric America
"It's got to be 5pm somewhere!"