TABLE OF CONTENTS Our job is to make holes in parts. If we get the holes right, the parts will go together right.
Michael Gorden, Ford Motor Company
This chapter introduces the mathematics necessary to position and orient parts in space with respect to each other. This is the basis of what we call an assembly model. It captures mathematically the physical way that parts are located with respect to each other, namely by means of assembly features, which are the places on parts that join them to neighboring parts. Our mathematics will permit us to describe features using the same symbols and methods that are used to describe relative positions and orientations of parts in space. Finally, we will see how variations in feature size and location on parts can be analyzed to see their effect on the size and shape of the assembly.
An assembly model should be able to provide the basis for computerized tools for designing assemblies. This means not just permitting the computer to draw the parts on the screen in the correct positions and orientations, but more importantly that the computer s representation should capture the fact that these parts comprise an assembly and that they are assembled to each other in a certain way. Then it can support assembly design and analysis calculations that use that information.
Most importantly, the assembly model should be able to capture the design intent of an assembly. The first level of assembly intent is the KCs.
