· Threads in the molded plastic parts are commonly made either by molding in or by tapping.
· Molded threads can be held to better tolerances than tapped threads of same size. Because tapped threads tend to have a minute chips and cracks on the surface.
· Molded threads must start and stop abruptly.
· Feather edges should never be specified because they are the weak areas in the part or mold.
· External threads can be molded using a split mold, however, the excessive flash may be present which will interfere with the subsequent assembly. A chase operation can prevent this, but it is an extra and costly step.