TABLE OF CONTENTS We don t design assemblies. We design parts and try to assemble them.
This chapter addresses the questions What does it mean to design an assembly? and How do we know when we have a good design? To answer these questions, we will bring together all the items from the previous six chapters. Our aim is to be able to present a unified way to lay out, analyze, outsource, assemble, and debug complex assemblies. To accomplish this, we need ways to capture their fundamental structure in a top-down design process that shows how the assembly is supposed to go together and deliver its key characteristics (KCs). This process should
Represent the top-level goals of the assembly
Link these goals to engineering requirements on the assembly and its parts in the form of KCs
Show how the parts will be constrained, and what features will be used to establish constraint, so that the parts will acquire their desired spatial relationships that achieve the KCs
Show where the parts will be in space relative to each other both under nominal conditions and under variation
Show how each part should be designed, dimensioned, and toleranced to support the plan
Assure that the plan is robust
A clear statement of these elements for a given assembly is called the design intent for that assembly.
This chapter describes a concept called the datum flow chain (DFC) to capture assembly design intent. [1] A DFC is a delivery chain for a KC, defining...
