Multi-Body Modelling

I wonder if it's needed to fully support the unite capabilities.  How else would you reuse an existing multi-body part from another CAD system in Creo today???

I will say that from a file management perspective, it is very helpful to have a multi-body part represented as a single component.  For example, while a nitrogen gas spring, or hydraulic cylinder really is an assembly, if you're not the manufacturer you probably don't want to manage it as such.  It's much nicer to treat it as a single part number and single model in Creo (and Windchill) while still having the ability to manipulate it like an assembly (change stroke length, etc.).  Today you can do this in Creo, but you have to be super careful to keep enough of a gap between the different parts or they will instantly merge into one solid.

Frequently we will take purchased assemblies and combine them into a single model, just because we don't want hundreds of individual assembly components cluttering up things.  I don't really care what pieces a manufacturer used to create a conveyor (for example), I just want the finished conveyor as a single model.  I think it would be slick if PTC provided the ability to turn an assembly into a single multi-body part (and maybe even back again.)

Aside from Tom's use case for assemblies that you'd like to track as a single model, I'v also sued multi body modeling in SW to create complex shelled parts. 

Imagine a box that's open on two sides with a center wall somewhere in the middle. Create two separate bodies, shell each and then merge them. 

I've been in many situations where I needed to shell partly from one side and partly from another. Being able to split it into two bodies, shell and then recombine would make that easier.

Or a part that needs to have two areas shelled at different thicknesses.  Model as separate bodies with their own shell features and merge them.

Once you have the option available, you can imagine things it'll let you do easily that having a single solid doesn't allow or makes difficult.

I do like that Creo treats a part as a single component.so I wonder if there would need to be a separate designation for an assy treated as a single item like Tom describes.

I concede those are pretty good reasons.

For the "multi-Shell need that you described Doug, I have just created quilts with offsets and then merged them. Granted each use case is unique and one technique is not the catch all.

I guess my original interest was concern over whether this added functionality would become, over time, the rule or the exception to the rule.

In my opinion, the lack of support for multi-body parts in Creo is a major problem.

In my company, this problem primarily relate to welded assemblies.

A typically welded assembly in my company (oil & gas) consist of hundreds of steel plates welded into complex steel structures.

As we do not do in-house manufacturing, we do not create individual drawings and part-numbers for the individual plates in the structure (only for the structure itself)

Without the support of multi-body parts, we have to manage thousands of models within our PDMLink system that really have no practical purpose other than slowing us down when doing activities such as: Add to/Refresh Workspace, Check In/Out, Revise, Promote etc.  

If Creo included multibody parts they wouldn't be able to charge extra for the "Advanced Assembly" module. I was shown the functionality in SolidWorks and realised that all the skeleton model and copy geometry complexity could be eliminated, along with a £1000 a year to PTC to maintain the Advanced Assemble extension.