Integration with Other Applications > Managing CAD and Part Relationships in Windchill > Part and CAD Association Overview
  
Part and CAD Association Overview
In top-down design (TDD), you can modify the Windchill product structure and then rebuild the CAD structure to synchronize it. This is sometimes referred to as a reverse build: building the CAD structure from the product structure. Once built, the CAD structure is said to be annotated and in sync with product structure. To continue the cycle, you must open the CAD structure in its CAD authoring tool (Creo Parametric) and confirm the changes pushed to it from the Windchill product structure. Checking in the CAD structure completes the TDD cycle.
For more information, see Top-down Design
Characteristics of Part and CAD Document Relationships
Prior to Windchill 10.0, the association between a CAD document and a Windchill part required the same (Modify) access control to exist on any state in order to modify the CAD document. It is now possible to update (check in/out) the CAD document even if the user does not have sufficient access to the part. In addition, the action of associating or disassociating a part and CAD document requires an iteration of the part.
For more information about comparing and editing CAD and product structures, see Managing CAD and Part Structures in Windchill.
Prior to release 10.0 the build did not populate occurrence information on a built product structure. Top-down design and flexible product structure editing made available in release 10.0 is dependent on the occurrence link information being instantiated properly. This is mostly applicable to the proper control over the deletion of parts from a CAD-driven product structure.
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Due to the changes in Windchill 10.0, if you upgrade to this release, you will notice that the build status on the usage link indicates that the build is ‘Completed.’ However, this is somewhat misleading. If you navigate to the Occurrences tab, it shows that the build status remains 'to be built'. Prior to leveraging the new capabilities in Windchill 10.0, whenever editing a Windchill product structure, a new build should be executed.