today morning, you want to know some things about thread ring cavity, actually thread ring cavity is a kind of active insert used to mold the outer thread of the plastic parts, which shall be protruded together with the parts after molding and dismounted outside the mold, it’s length of fit is 5—8mm, to make it easy for assembly, the remaining parts are made into 3—5 degree obliquity, and a four-sided plane is modified at the lower extreme, so that it will be convenient to screw it from the plastic parts with tools.