Final answer:
In CAD, a concentric mate cannot be applied between two edges; it is meant for aligning circular features like holes or cylinders. For two edges, mates such as coincident, parallel, or distance are suitable.
Step-by-step explanation:
The type of mate that cannot be applied between two edges in a computer-aided design (CAD) program is a concentric mate. Concentric mates are typically used to align cylindrical faces, holes, or arcs so that their centers are the same. This mating feature is not suitable for edges because edges, being linear rather than curved, do not have a central axis around which they can be aligned concentrically.
In CAD, there are several different types of mates that can be used for various assembly requirements, such as coincident, parallel, perpendicular, tangent, and distance mates. Each type serves a specific purpose to ensure correct alignment of parts in an assembly.
For example, to align two straight edges to be flush with each other, one would use a coincident mate. If the goal was to have two edges remain parallel at a set distance from each other, a parallel mate or a distance mate would be appropriate.