Method of making injection-molded slide fastener sliders

A method of making an injection-molded slide fastener slider, the slider including a slider body having upper and lower wings joined at their front ends by a neck so as to define therebetween a Y-shaped guide channel, an arch-shaped support lug integral with a top surface of the upper wing and extending longitudinally of the slider body so as to define jointly with the top surface a transverse hole, and a pull tab pivotally connected with the arch-shaped support lug and having a pintle loosely received in the transverse hole, said method comprising the steps of:

• (a) providing a mold including a pair of complementary mold members jointly defining therebetween a first mold cavity for forming the slider body including the support lug and a second mold cavity for forming the pull tab except the pintle, said first and second mold cavities communicating with each other, said mold further including a main slide core slidably disposed in said first cavity and having an auxiliary slide core slidably associated therewith, said main and auxiliary slide cores jointly have a shape complementary to the shape of the transverse hole, said auxiliary slide core being movable between a first position to block communication between said first and second mold cavities and a second position to allow communication between said first and second mold cavities;
• (b) closing said mold while keeping said auxiliary slide core in said first position;
• (c) injecting an amount of molten material into said closed mold to fill said first cavity, thereby forming the slider body and the support lug;
• (d) thereafter, while keeping said mold in a closed condition, moving said auxiliary slide core from said first position to said second position to form a third cavity complementary in contour to the shape of the pintle, partly defined by an underside of the just molded support lug and communicating with said second mold cavity;
• (e) then injecting an amount of molten material into said closed mold to fill said second and third mold cavities, thereby forming the pull tab with its pintle pivotally connected with the lug on the molded slider body;
• and
• (f) cooling the molded slider body and pull tab for a length of time adequate for solidifying thereof and then removing from said mold the slider body and the pull tab molded in a coupled state.