In an ideal world, a full CAD structure of your product would contain everything you would need to make or order in order to assemble one. However in reality this is seldom, if ever, the case. There are many objects that need to be ordered that are never modelled fully in CAD (such as any kind of fluid), and there are various objects created in CAD which only exist to assist in designing the real parts (Such as wireframe, reference package and mannequin models). So obviously there’s a need to have a separate Engineering BOM (or EBOM) to contain this information and filter out the unneeded BOM data.
This is sadly not the end of the story. You need to work out and have the tools and consumables available to actually assemble your product. And let’s face it, very few design departments structure the assemblies in CAD in the same manner they will actually get assembled on the workshop floor.
To complicate matters further, what was once an Assembly at one stage of production is then logged and tracked as a single component when assembling later on. Enter the DELMIA Manufactured item definition app:
Here, a CAD structure has been reorganised into a similar, but noticeably different layout by linking it to specific manufacturing assemblies.
The manufacturing tree also contains other types of nodes in the tree, since not every stage of a manufacturing process is assembling pre-existing parts, the following types can be inserted to represent other operations and materials that may be used during manufacture:
There is also nothing stopping you from linking multiple manufacturing assemblies to the same CAD structure, allowing multiple manufacturing structures to be made, perhaps to manage different stages of the process, or to plan how different sites with different facilities will go about manufacturing the same product.
And thus you can have a series of manufacturing BOMs you can then either export as-is, or expand further by creating manufacturing timing plans and laying it out into a manufacturing workshop layout, but that’s a topic for another article.