You can create hole features in assemblies.
To create an assembly feature hole:
-
Click the planar face approximately where you want to create the hole.
-
Click Simple Hole
or Hole Wizard 
(Features toolbar), or click , then Simple or Wizard.
-
Set the options
in the Hole PropertyManager or Hole Wizard Type PropertyManager. Under
Feature Scope, specify which
components you want the feature to affect.
You can use
Hole Series to
create an assembly
feature
that
creates hole features in the components of the assembly.
Some
designers create holes using assembly features
instead
of creating hole features in the individual parts. For these
designers,
SOLIDWORKS
has the Hole Series tool. This tool
creates assembly feature holes, but the hole geometry is created in the
individual part documents, not in the assembly.
Assembly
features cannot be propagated to Toolbox parts. You cannot select a Toolbox part
for a Hole Series as this assembly
feature is always propagated to parts.