Managing Component Libraries
You can design components to be used in one or more assemblies and then save them in a component library. Refer to the figures below. Your assembly models can then retrieve an instance of the components from the library as needed ("bottom up" design).
This is the most efficient way of designing large or complex assemblies. You can also design or edit a component while in the assembly ("top down" design). See Basic Assembly Modeling Concepts for more details.

Component Library Strategy

Data Management Strategies for Design