What is the purpose of the "Mate" feature in an assembly?

The "Mate" feature in SolidWorks assemblies is essential for defining the relationships and constraints between components. When building an assembly, it is crucial to establish how parts interact with one another to ensure proper functioning and alignment. Mates allow users to specify the relative positions and orientations of components, such as aligning holes, faces, or edges.

By applying different types of mates—like coincident, parallel, perpendicular, distance, and angle—designers can control how components fit together. This is vital for achieving a working assembly where parts can move correctly, if they are designed to do so, or remain fixed in the intended configuration.

Creating new 3D sketches is unrelated to the purpose of the Mate feature, since that function serves more for design and layout planning. Calculating physical properties of an assembly and optimizing for manufacturing are also distinct tasks that take place after the assembly has been constructed and constrained properly through the use of mates. Hence, the primary and correct role of the Mate feature is indeed to define the relationships and constraints between components in an assembly.