Why Does My EPDM Calculated BOM Change?

In SolidWorks Enterprise PDM, if you look at a computed BOM of a particular version of a file, you would expect that if you looked at that same BOM a year from now it would be exactly the same.

Likely, you would be wrong.

Here is why. A bill of material column set can contain one of two different entities. Variables and file properties. Variables do as you would expect. They are [and always will be] the variable values of all BOM components at the time the assembly was checked in. However, file properties may change – they are the current values of the file’s properties.

In the example below, any row with the variable inside of the “<>” brackets is a file property. Thus, in this example, the file name and state’s value will be the current name and state of the component. The description’s value (a variable) will be the value of the description variable at the moment the assembly was checked in. i.e. The description will be constant for that BOM version.

To avoid confusion to users, I like using “Current” as a prefix for the header names, so users can easily tell the difference.


SPECIAL NOTE: The quantity (reference count) of a part within an assembly is an exception! The quantity of a component will not change for that version's BOM.


Jeff Sweeney is an Engineering Data Specialist at 3DVision Technologies, a SolidWorks Value Added Reseller with locations across Ohio, Indiana, and Kentucky.  He is a regular contributor to 3DVision Technologies' Blog where you will find new ideas to improve your productivity with Enterprise PDM and SolidWorks.