Tunnel Gate Injection Molding

Tunnel gates can t be used with every material available for injection molding.

Tunnel gate injection molding.

I mold tunnel gate inserts are recognized worldwide as innovative products with high cost reducing potential for moldmakers and molders. From there the material would flow up the tunnel gate and into a short cold runner with an edge gate feeding the top inside edge of the gauge cutout. Clearly when designing for injection molding gate selection may require some deliberation. Assuming you haven t.

Compatible materials for tunnel gates. The final part as seen at right shows the post from the pin or tunnel gate that was removed in a manual process. While the size of the gate usually affects the size of the vestige the predominant controlling factor on how clean or how high a vestige you get is based on the angle of the wall it s gated into. Plastic molding tutorial 112 varieties of tunnel gates.

Tunnel gate diameters vary from 0 5 0 8 mm for unreinforced plastics to larger diameters of 2 mm plus for reinforced materials. Tunnel gates also get a bad reputation for leaving a high gate vestige especially when the size of the gate is large. If a material is too flexible a proper shearing action isn t achievable. The tunnel gate submarine gate is used very frequently as a type of gate having a structure that automatically cuts the molded item and gate at the time of opening and closing the parting surface.

These gates tunnel under the tool steel into a wall section. If the injection molding requirements meet the smaller the number of gates are the better it is it would reduce the weld marks. Effectively it was a tunnel gate jumping into another tunnel gate. Pin gates are sometimes called post or tunnel gates and are commonly used on gears as shown here at left.

Injection molding gate types edge gates. As the part ejects the tunnel gate is sheared off as the ejector pin pushes up on the runner causing the gate to rip at the opening of the gate orifice.