Designing Plastics Parts for Assembly

Preface 1st Edition

Dr. Peter Dewhurst,

Department of Industrial and Manufacturing Engineering,

University of Rhode Island

November, 1993

Providence, Rhode Island

It gives me great pleasure to write this preface for such an important contribution to engineering design. It is rather sad fact that while the creative use of plastics has changed the very structure of consumer products over the past decade, many engineering students graduate with very little knowledge of polymer engineering or plastic design principles. This book written by a recognized expert and practitioner in the field of plastic component design is both a valuable text for engineering courses and a resource for practicing design engineers.

The full potential for the use of plastics in consumer products became recognized in the mid 1980's through the pioneering development of the IBM ProPrinter. The ProPrinter destroyed the myth, prevalent amongst product engineers at that time, that such design elements as plastic springs, plastic bearings, plastic securing elements, etc., lacked the structural integrity of their more common metal counterparts. In the ProPrinter, not only were these plastic design features shown to have the required reliability in regular use and abuse, they were combined into single parts to produce a new level of design elegance. For example, the injection molded side-frames of the ProPrinter, which support the rollers and lead screw, incorporated bearings for all of these rotating members, springs to maintain the required paper pressure, and cantilever securing elements to allow the frames to be snap fitted into the base. The result of such innovative design details produced a desktop printer which could be assembled in only 32 final assembly steps compared to the 185 steps required to assemble its main competitor in the marketplace.

Since the emergence of the ProPrinter, smart plastic design has become an essential tool in the competitive battle to produce products which have simpler structures with smaller numbers of discrete parts. Part count reduction, in particular, has been shown, through numerous case studies published over the past five years, to have a ripple effect on product manufacture which improves the efficiency of the entire organization. Fewer parts means fewer manufacturing and assembly steps, and fewer joints and interfaces, all of which have a positive effect on quality and reliability. Moreover, a reduction in the number of the parts results in a direct attack on the hidden or overhead cost of an organization. Thus, fewer parts also mean fewer vendors for purchasing to deal with, less documentation, smaller inventory levels, less inspection, simpler production scheduling and so on.

Designing Plastic Parts for Assembly tackles all of the important issues to be faced in designing multi-feature complex plastic parts. The book is thus much more than its title suggests. It deals with essential fundamentals for the development of competitive consumer products.

©1994 Carl Hanser Verlag. All rights reserved.

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