You can build complex assemblies consisting of many components, which can be parts or other assemblies, called sub-assemblies. For most operations, the behavior of components is the same for both types. Adding a component to an assembly creates a link between the assembly and the component. When SolidWorks opens the assembly, it finds the component file to show it in the assembly. Changes in the component are automatically reflected in the assembly.
The document name extension for assemblies is .sldasm.
To create an assembly from a part:
Click Make Assembly from Part/Assembly (Standard toolbar) or File, Make Assembly from Part.
An assembly opens with the Insert Component PropertyManager active.
Click in the graphics area to add the part to the assembly.
SolidWorks makes the first component fixed.
The following topics describe the basics of creating an assembly from components you have already built and general information about working with assemblies.