Products with External Undercuts

Products with external undercuts (e.g., spools and bobbins, transportation boxes with handles, handled vessels, parts with external threads). 

Products with external and internal undercuts (e.g., bumper fascias, camera housing). 

The weld was riddled with mildly undercut, gaping pits. Attack was confined to fused and heat-affected zones, with a pronounced lateral or circumferential propagation (as in Fig. 6.10). The resulting perforation at the external surface was quite small. Pits were filled with deposits, friable oxides, and other corrosion products. Black plugs embedded in material filling the gaping pit contained high concentrations of iron sulfide. Bulk deposits contained about 90% iron oxide. Carbonaceous material was not detected. 

There are two basic ways of joining the hard and soft components of a composite, chemical and mechanical [14], A purely mechanical joint is obtained by overmolding apertures or undercuts in the hard component. The use of internal or external adhesion promoters permits the production of composites with liquid-tight frictional joints [15], A bond formed by chemical cohesion has a number of advantages over a mechanical joint formed by interlocking [16] ... 

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