Many complex assemblies have "layers" of parts that are not always immediately visible. Transparency is a useful feature to use for 3D CAD assemblies when you want shop floor operators to be able to "look inside" an assembly's layers or "look behind" specific parts to reveal additional parts underneath.
Note
Using the Transparency feature is temporary; changes you make are not saved with the selected view. If you want to show an assembly with transparent parts, use the Snapshot 
toolbar button to save a *.png image of the assembly with the transparent parts.
In the Process Definition window, select the desired assembly view on the right side of the window under Views (or create a new view).
Do one of the following:
Select the part you want to make transparent to highlight it using the current highlight colors (use Ctrl+click to select multiple parts), then right-click a selected area and select Transparent from the menu.
Right-click the part you want to make transparent, then select Transparent from the menu.
The transparency is applied to the selected part(s).
In the following illustration, you can now see the bolts that were previously hidden.
To make a transparent part fully visible again, right-click the part, then select Transparent from the menu to turn off transparency.
Note
If you highlighted a part before selecting Transparent, click a blank area of the window to remove the highlight colors.