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SA_103584247-Bedrock
7-Bedrock
October 23, 2025
Question

How to represent CAD assemblies that should be treated as single parts (purchased items) in EBOM?

  • October 23, 2025
  • 3 replies
  • 533 views

Version: Windchill 13.0

 

Use Case: In our design environment using NX + Windchill, we have components such as motors, bearings, and linear guides that are modeled as assemblies in CAD (CAD-BOM). However, in the EBOM, these are treated as purchased single parts that are procured as complete units from suppliers. For example, a linear guide assembly might consist of a rail, carriage, and screws in CAD, but in EBOM, it should appear as a single purchased item with one WTPart number.


Description:

We would like to know how other companies manage or represent this kind of data —
assemblies in CAD that can reasonably be treated as single parts in EBOM (such as purchased assemblies or supplier-provided modules).

  • How do other organizations express or manage these cases in their EBOM structure?

  • Does PTC have any recommended or standard method for handling such data?

  • Are there best practices for linking a CAD assembly to a single WTPart (purchased part),
    or configuration options to collapse the CAD substructure in EBOM generation?

Any real-world examples, configuration hints, or recommendations from PTC would be greatly appreciated.

Thank you in advance for your insights and advice.

Best regards.

3 replies

avillanueva
23-Emerald I
avillanueva23-Emerald I
23-Emerald I
October 23, 2025

There are many way to achieve this and it should be CAD agnostic. First off, you want to control how your CAD assembly builds and associates to WTParts. In this case, you do not want the underlying CAD models associated to this CAD assembly to make WTParts and build a BOM. This can be done by attributes which in preferences can be set to block part creation and association. 

Next, the assembly itself should have a WTPart but linked as an image type association. This means it will not try to create a BOM structure from its components below. The default is owner which will try to create a BOM for it. This might require manual flipped on defaults or association on initial check in or modifications later. 

If you blow by all these and you see a BOM created, you can simply edit that to clear the structure from the WTPart linked to your CAD assembly. Also flip the association to Image type to stop it being created in the future modifications. I think that should achieve what you want to do. 

D
DanWolf14-Alexandrite
14-Alexandrite
November 3, 2025
@avillanueva wrote:

Next, the assembly itself should have a WTPart but linked as an image type association. This means it will not try to create a BOM structure from its components below. The default is owner which will try to create a BOM for it.

Is that default behavior or affected by some preferences?  We have many cases of assemblies being associated as Owner and Image to a WTPart and have never experienced an assembly's Image association causing BOM creation of its components.  In my experience, that depends on the components' WTPart associations.

 

A common use of this for us is hydraulic hose assemblies.  The same physical hose might be installed mutliple times and in different ways because it's flexible.  We model this in Creo with a different "state" assembly for each of those variations.  The WTPart will have an Owner association to the first hose assembly created and Image associations to any other "state" assemblies, because there can be only one Owner but multiple Images.  When there is only one assembly, it is always associated as Owner to the WTPart so the WTPart inherits attributes from the Owner model.

    D
    17-Peridot
    Dobi17-Peridot
    17-Peridot
    November 4, 2025

    Here are some references on the association types:

    Help center documentation (WC 13.0.2) 

    CS37439 on association types.

     

    Your hydraulic hose example sounds a lot more like a flexible component use case if you're using Creo. 

      D
      17-Peridot
      Dobi17-Peridot
      17-Peridot
      October 24, 2025

      Are your CAD assemblies genuinely purchased components? Do you bring them in as STEP files into NX but they just import as assemblies? If yes, what we do (also NX+Windchill) is import the step data as a flattened assembly in NX to the work part. It'll create bodies instead of individual parts so then we don't have to manage the WTPart associations and there's a single Owner-linked WTPart for the eBOM.

      The other way to go on the CAD end that worked for us was to take the incoming assembly and then Wavelink it to a new part. Once you have the geometry, break the Wavelink and you have a single part with all of the features. 

       

      Otherwise if you need the detail of the individual components in your CAD but won't want that detail in the eBOM, what @avillanueva  said is the way to go. 

      V
      vnamboodheriCommunity Manager
      Community Moderator
      October 30, 2025

      Hello @SA_10358424, 

       

      It looks like you have some responses from our community experts. If any of these replies helped you solve your question please mark the appropriate reply as the Accepted Solution. 
      Of course, if you have more to share on your issue, please let the Community know so other community members can continue to help you.

      Thanks,
      Vivek N.
      Community Moderation Team.

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