The proliferation of plastic in parts, and the ability to mold such parts of great complexity at little cost penalty, has resulted in the growing use of integral attachment in the form of snap-fit features in designs. Heretofore, the great diversity in geometry of mating parts and of available integral attachment snap-fit features (e.g., cantilever hooks, compression traps, bayonet-fingers, etc.) has made it appear that assembly design possibilities may be unbounded, and that attempts at optimization might be intractable. This paper enumerates all possible assembly design options using a hierarchical classification scheme. In so doing, it guides new designers and validates choices for experienced ones. The result is great order and simplicity that facilitates better understanding of this assembly joining method, better communication, development of design aids, and improved and extended attachment performance.

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