February 27, 2005
Notes on Ulrich, Eppinger - Product Design and Development
Karl T. Ulrich and Seven D. Eppinger
Product Design and Development - 2nd ed.
Irwin McGraw-Hill, 2000
ISBN 0-07-229647-X - Stanford call number HD 31 U47 2000 ENG
Chapter 12 of this textbook presents an overview of the functions of prototyping in the industrial product design process. A running example is used throughout the chapter - the redesign of the trackball for the Apple Duo notebook computer. A prototype is defined as "an approximatrion of the product along one or more dimensions of interest." Prototypes are classified along the following continua: physical--analytical, comprehensive--focused. Often, separate "looks-like" and "works-like" focused prototypes are created side-by-side. The reason given is that building comprehensive prototypes takes longer/is costlier. Comprehensive analyitcal (mathematically modeled) prototypes are not feasible in practice. Prototypes have four main uses: as learning tools; as communication artifacts for management, team members, customers; as integration tools to check if sub-assemblies fit together; and as milestones to demonstrate progress and existing functionality. (Note: user testing is not mentioned.)
Principles of prototyping: analytical prototypes are more flexible than physical prototypes since parametric models can be changed without rebuilding everything. Physical prototypes are necessary to check unanticipated behaviors due to the laws of physics in the real world. Prototyping can save money by moving iteration cycles away from the costly manufacturing stage. Prototypes may expedite other development stages such as mold design if prototype artifacts can be reused for production (e.g., CAD files?). Prototypes may restructure task dependencies?
Two particularly important prototyping technologies are 3D computer modeling and free-form fabrication (3D printing). Stereolithography itself is often referred to as rapid prototyping in the community - a source of confusion.
Prototyping brings with it the danger of sinking into Clausing's "hardware swamp" - spending time building and debugging prototypes that do not substantially further the larger product development project. Careful definition of the purpose and scope of the prototype is needed. Purpose: what are the learning, communication, and integration needs the prototype should fulfill? What is the level of approximation? Ignore all factors that are not part of the analysis. Come up with a testing plan for the prototype, make a schedule and stick to it. A real-world fact: it is usual to buld at least three milestone prototypes: alpha, beta, and pre-production. We are targettign alpha prototypes.
What are wire-wrapped boards? Posted by Bjoern Hartmann at February 27, 2005 8:33 PM