Clearly when designing for injection molding gate selection may require some deliberation.
Tunnel gate injection molding.
The final part as seen at right shows the post from the pin or tunnel gate that was removed in a manual process.
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.
The tunnel gate could then feed into another tunnel gate coming in from the opposite direction.
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.
Assuming you haven t.
These gates tunnel under the tool steel into a wall section.
I mold tunnel gate inserts are recognized worldwide as innovative products with high cost reducing potential for moldmakers and molders.
Plastic molding tutorial 112 varieties of tunnel gates.
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.
Compatible materials for tunnel gates.
Tunnel gates can t be used with every material available for injection molding.
That s because a tunnel gate relies on the ability of the material to shear on the tunnel gate edge as the part is ejected.
If the injection molding requirements meet the smaller the number of gates are the better it is it would reduce the weld marks.
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.
Effectively it was a tunnel gate jumping into another tunnel gate.
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.
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