3.8 RIGID LOCATING FEATURES (OR LOCATORS) FOR ELASTIC SNAP-FIT ASSEMBLY

In all joining, the constraint ^[12] of parts in their appropriate positions, orientations, and alignments is the goal and the most important measure of success. By being properly constrained, the parts of an assembly or structure can operate to resist, sustain, support, and/or transmit loads as required for proper functioning of the assembly and for reliable and safe structural integrity. Constraint is also obviously the most fundamental of the key requirements of integral mechanical attachments. In rigid integral mechanical attachments or rigid interlocks, that constraint comes from the rigid nature of the parts and/or the actual attachment and locking features involved in the joint. As will be seen in Chapter 4 on elastic integral mechanical attachments, typified by so-called "snap-fits," joining requires that a flexible locking feature deflect elastically during part-to-part assembly to allow engagement of the mating part and a base part, followed by the recovery of the locking feature toward its original, non-deflected position. Once this occurs, the physical interference needed to lock the parts together has been achieved.

Bonenberger (2000) defines constraint features in elastic snap-fit assembly as "the locking and locating features that actually hold the parts [of an assembly] together." He further properly divides constraint features in snap-fit assembly into two major groups: locators and locks. As the names imply, "locators" both ensure and facilitate that two parts of the intended assembly, in general, and the integral feature(s) being used to...