3.4 INTEGRAL RIGID LOCKING FEATURES

The class of integral rigid locking features differs from the preceding class of completely rigid interlocking joint elements (see Section 3.3) in that the parts involved allow attachment and locking to another part or parts, but that(those) other part(s) may or may not contain integral rigid geometric features for attachment and locking. In the class of completely rigid interlocking joint elements, both (or all) parts to comprise the particular joint(s) have integral rigid geometric features. Moreover, for completely rigid interlocking joint elements, both (or all) joints elements are actually parts with a primary function other than simply allowing joining. Some, though not all, parts classified as integral rigid locking features have the primary function of allowing joining and may or may not, beyond that, have another specific function in the assembly. Another way of highlighting the difference is that with completely rigid interlocking joint elements, the key point is that they are always complete parts, in and of themselves, that can be rigidly interlocked. With integral rigid interlocking features, the emphasis is on the rigid features that allow interlocking between or among parts, not on the parts themselves. The difference is subtle and is mostly one of degree more than substance perhaps, but in many, if not all, cases the subtlety is worthwhile.

As shown in Figure 3.2, there are four major sub-classes within the class of integral rigid locking features: (1) splines and integral keys; (2) knurled surfaces; (3) wedges and Morse tapers;