When looking at the BOM in an Inventor assembly you will notice there are 3 tabs.

• Model Data
• Structured
• Parts Only

When first looking at it, it might be confusing.  In this blog we will look at the the differences between the 3 tabs.

The Model Data tab will reflect all the parts, sub-assemblies and assemblies you have created. In the below image you will notice that any parts and assemblies in the first level are shown and then if you would liek to go into the second level and beyond you will need to select the plus button drop down to view those levels.

The Structured tab is displayed in the below image and you will see only the first level of your BOM.  Notice that even though you have a total quantity of 4 x Part 1 and 4 x Part 2, because 2 of each these parts are nested in a sub-assembly it does not get shown/reflected in the Structured tab.

The Parts Only tab will look into all levels and promote the parts and calculate the number of parts.  Notice there are no assemblies and it is showing the total number of parts unlike in the structures tab.

When creating parts and assemblies in Inventor you can allocate a BOM structure.  When you change the BOM structure for the different components the information that is shown in the 3 tabs does change.  Some components are hidden and some are not.

This BOM structure has the following designations.

• Normal
• Inseparable
• Purchased
• Phantom
• Reference

If I make a component Inseperable or Purchased then all the tabs look identical to the normal structure except for the Parts tab.  I have changed an Assembly to be inseperable so the BOM recognises it as one part.  The reason for this is that you need to physically hurt that assembly to pull it apart (think hammer or a stick of dynamite).

If I make a component a Reference or Phantom part or assembly then the parts or assemblies will not be visible in the Structured and Parts Only tab.