Basic Assembly Constraints & Concepts
Assembly constraints are parameters that define the geometric relationships between components in a CAD assembly. These constraints include: Mate/Flush Angle Tangent Insert
A component floating in space has six degrees of freedom: • 3 rotations around the X, Y, and Z axes. • 3 translations along the X, Y, and Z axes. Degrees of freedom are systematically removed in an assembly until only the desired components are allowed to move.
Mate Constraint • Constrains two faces, edges, points, or axis together. • The red arrows represent normal vectors and point towards each other.
Flush Constraint • Constrains two faces or work features together. • Normal vectors will point in the same direction.
Angle Constraint • Constrains two faces or edges at an angle to one another. • Normal vectors parallel to each other equal 0° angle.
Insert Constraint • Constrains a cylinder flush into a hole.
Tangent Constraint • Constrains a curved surface to a plane or another curved surface.
Base Component • The first component placed in an assembly should be a fundamental part or sub-assembly, such as a frame or base plate, on which the rest of the assembly is built. • The first component in an assembly file sets the orientation of all subsequent parts and subassemblies.
Grounded Component • When the first component is placed in the assembly, its origin is coincident and aligned with the assembly coordinate origin. • All degrees of freedom are removed from the first component. • The base component will be grounded and should be left that way.
Patterning Component • This function duplicates one or more components and arranges the resulting occurrences in a circular or rectangular pattern.
Replace Component • In the design process, one often needs to replace one or more components in an assembly. • The new component is placed in the same location as the original component, but assembly constraints may be deleted in the process.
Editing Components • When you double click on a component, you will exit the assembly environment and enter the part environment. The other components in the assembly will become translucent. • When you are finished editing the part, you will exit the part environment and return to the assembly environment.
Subassemblies • A group of components that are constrained to act as one component in a larger assembly.