There are scenarios where our engineers need to see 3d representations of certain items that would NOT have a unit of EA for a WTPart BOM structure in Windchill. Examples:
I would prefer to not have engineers manually adding quantities/units in Windchill BOM structure. I would prefer that we use bulk items which automatically output the correct length/mass of an item into Windchill WTPart structure. I am trying to figure out if there is a way to combine bulk items WITH 3D models, where the bulk items measures the values from it's 3d version of the assembly. However, making it too difficult with relations using "fid_..." is not helpful either. If someone has any bright ideas, that would be really helpful!
The first difficulty to overcome with this type of thing is developing some sort of method of evaluating the geometry to calculate length (or area). I don't see any way for an assembly to be "smart" enough to do this type of thing itself. The only way I can think of is to have parameters in the assembly for the lengths/areas/volumes of interest, something like lenPutty, lenTape, etc.
To calculate the values, I'd probably have to use an approach like:
(1) Define a measure feature or features for the quantity(ies) of interest. Length of part edges adjacent to each other that will need to be taped, for example. One length for part A to B, one for part A to C, etc.
(2) Use the measure feature(s) to calculate the total of the quantity of interest. For example, total tape length for all joints between part A and parts B, C, etc.
(3) Apply a factor to "adjust" the calculated value, allowing for the fact that you will most assuredly not use the exact calculated amount of tape or whatever, because there's always lost length to trimming, overlap, etc.
The big problem with this type of approach is if you subsequently iterate the design and make a significant change to the topology of the model(s). You will likely have to redefine one or more of the measure features, and revise the pertinent relations, but that's the price you pay for the results. A bit of overhead at the beginning, but it pays off if you are re-using the methods in future designs.
That's my 10 minute conjecture.
I think your approach is going to be limited to using relations within the model specific to the bulk items.
The big question running through my mind - are you setting up a family table for the item so that you can instantiate the variations of each version of the same bulk item (e.g. tape lengths, putty quantities, etc) so that you avoid relation problems
The direction of the relation will also need to be considered (part relation looking at assembly? vs assembly relation updating the part).
As far as my crude idea goes, I was figuring on the assembly updating the bulk item parts it contains. The difficult part to envision is how to get the geometric data needed to calculate the different bulk item quantities.
I made certain parts for bulk use (NOT using Creo's "bulk" part) for this very use. I have an INTEGER parameter I call "BOM_OBJECT_TYPE" that will automatically fill out the qty as "A/R" via relations in the repeat region table, but I'm sure you can do something similar where the column in the table can have 2 parameters driving it so that the parameter on the left is a REAL NUMBER and the next one to the right is the one that instead of inserting the text string: "A/R", it inserts the string "INCHES". Of course, then you'd need several of these ones for "INCH", "GRAMS", etc., but I think it'd be doable. The easiest way is to put that info in the title column and maybe use "A/R" or leave a blank in the Qty column for that item.