Mold gate submarine

Typical gates for fascia moldings include submarine gating into a protruded tab which is formed as part of the ejector system. The tab is then left on after ejection for use as location points for further decorative processes. Upon completion of decorative processes (i.e. silk screening, painting, etc.) the tabs can be broken off or left as part of the final product. 

A submarine gate (Figure 2.1 Ih) is one that goes through the steel of the cavity. It is very often used in automatic molds. 

When designing molds for HIPS, and GPPS, the principles are very similar but these materials do tend to flow more easily. This results in smaller runner systems, e.g. 2.5 to 5.0mm (0.098 to 0.197in) in diameter, and thinner wall sectioned components. It can also withstand being flexed without cracking. Due to the flexible nature of HIPS, submarine type gates and reverse tapered sprue pullers are widely used for cold runner molds which are intended to cycle automatically. Small undercuts can be jumped or bumped off during ejection of the component. 

Submarine (or tunnel or chisel) gates are fine-diameter (0.25-2.0 mm) gates that are angled from the parting line. Used in two-plate molds, they permit automatic degating of the part from the runner systems. 

With a curved tunnel gate (also called submarine gate or cashew gate, Figure 1.38) it is possible to position the gate on the back of the molded part where the appearance is as little affected as by the markings of the ejector pins. 

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