BOM tables on 2D production drawings

[cc-2]

Hello

I would like to start a discussion to see what type of practices are out there regarding the so called BOM table on the 2D production drawings.

Let me explain the context first and my understanding so far.

The design is first created in 3D and this CAD structure is technically the eBOM. You can assemble the model in many different ways, sometimes with tools that allow you to generate the model very quickly. Therefore at that stage you should not be concerned about how this will be made.

However, when you create the 2D drawing and insert the BOM table, that table, despite a few options, will create the BOM from the CAD structure.

Now imagine that this model is made at different factory (or even the same one but with different assembly machines (for sake of argument, one machine just need the components and it assembles the part, another one is semi automated and needs sub assembly first).

Either manufacturing process produces exactly the same assembly.

I think we all agree that for one unique partnumber you should have only one eBOM and therefore only one CAD asm file.

This leads to the situation that the BOM table on your 2D drawing cannot be the mBOM, because if it is, then what do you do for the other mBOM due to a different manufacturing process.

To me the mBOM should never be put on the 2D drawings. There should be a list of component maybe but the work instruction and mBOM should only comes to the shopfloor from the ERP system.

However,in my company some insist to have the BOM table on the 2D drawing to be the mBOM as they will make the part.

And as a consequence they model their CAD structure to be like their mBOM and that generates automatically the BOM table as a mBOM.

When I ask them if they will create a new model (leading to duplication and anyway PDMLink or ERP won't tell them create 2 different objects with the same number) when the manufacturing process is changed. I get no answer.

Have you faced such situation where production engineer wants their mBOM on the 2D drawings

Do you think it is good/idea practice ?

Of course one alternative is to manually create the BOM on the 2D drawing but this has also disadvantages.

To be the solution is simple. people who need to assembly the product must get the work instructions and mBOM from the ERP system. The drawings is only to make them understand how the product look like and which dimensions matters etc....

What is your view.

Thanks and best regards

[DonSenchuk]

Generally speaking from my experience, this is the exact reason there is a difference between Manufacturing Engineering and Product Engineering.

Product Engineering is concerned with the final product. To put it crudely, they don't care how the end product is arrived at, as long as it gets there accurately.

Manufacturing Engineering's responsibility is to create the Op Sheets (mBOM). Fortunately, there are several tools available in Creo Parametric to facilitate this. Even if one doesn't want to use Pro/Process (if it still exists; my experience with this is extremely limited) the use of Simplified Reps can achieve the mBOM and Op Sheets required of the assembly process.

You've asked the right question to which you're getting no answer. Another possible question is 'What happens if the manufacturing process changes? Do you revise every drawing of every assembly made in that department?'

Speaking in generalities:

* product engineering's drawings only get revised if there is a revision to the design, ignoring the manufacturing assembly process.

* If a design revision does not require a change to the manufacturing assembly process those Op Sheets could be left as is.

* If the manufacturing process gets changed (requiring a revision to Op Sheets) but the design is left the same, product engineering's drawings do not require a revision.

In my opinion, the drawbacks to trying to use an mBOM on the drawings that Product Engineering creates far outweigh any benefits.

[HugoHermans]

Hi Nacnac,

We put kind of an mBOM on our drawings, definitly not the eBOM. We developed a JLink application to create a text note, based on the BOM from ERP, and including the indices from the ProE BOM table, in order to align with the BOM balloons on the drawing.

This is a fairly decent solution, except that our environment does not prohibit to change the BOM in ERP without updating the drawing. So, basically, you always have to check ERP before you can use the drawing. So, that's my quest, why putting a BOM on a drawing?
In my former position, during a summer shutdown somewhere early 90's, all BOM's from all drawings were removed, so the only source of BOM's was ERP. Some years ago, I spoke to a CAD & PLM administrator, he went even further, he removed everything from the drawing that was available in the PLM database, and deployed an application that composed the print-out on the fly with up-to-date data.

Back to reality. I think you have to consider the technical drawing as a contract between R&D-Engineering and the rest of the company. It has to provide the information they need to do a good job, as close as possible to their needs. On the other hand, I discourage our designers to tweak the assembly structure in ProE (which is the result of and should support the creative process of designing) for the sake of a BOM on the drawing. This explains our approach.

Best Regards, Hugo.

[GregoryPERASSO]

Hello ,

Another questions about this topic .

-Do you create specific CAD or drawing for strict manufacturing purpose. Probably yes if you manufacture internaly some semi finished states before finally assembling parts ....

-Do you have more than one manufacturing BOM alternative ? For a same Part Number can you have different way to build it, depending of machine, plant etc ...

In my pevious company, we have done exactly what Hugo said. Remove any "PLM database" informations from drawings . Basicaly no BOMs, nortitle block, Only geometry. And all the infos are dynamically watermarked "on demand". With different scheme for manufacturing , engineering , maintenance or suppliers drawings (here for example no Change Recor Table. Only final Released Version)

And the BOMs (Engineering, Manufacturning and Service are clearly different structures, even if managed in a common cross Change Management process)

If a Design Drawing can be used in both eBOM and mBOM, it will describe both "views" of this Part Number

But if a specific drawing is neededfor a BOMManufacturing level ... Have to create it.... even if in some case it will contains some derivative information from the "upstream" Design 3D model or Drawing... (here from a CAD point of view, we use Family table or inheritance to avoid duplication ...)

regards

Gregory

[cc-2]

Hi

thanks for your response.

It seems that we all agree, Those days the 2D drawings should only show how the part looks like and the dimensions.

The ERP is then showing how it is made so mBOM should be removed from the 2D drawings.

Thanks, this confirms what I have been thinking for some time. Now the hard bit. How do you implement this !!!

Have a good weekend

Best regards