Gates connect the runner system to the cavity and are the orifices through which the melt enters the mold.
When you design gates, you should consider the following:
The final appearance of the molded part
Removal of the gate
Complexity of the cavity
The material used
The volume of the material injected into the mold
Before designing the runner system, you should run a Gate Location analysis for each cavity to find out the best gate locations. For parts where appearance is important, the gates should be narrow to prevent large blemishes on the surface of the part. A smaller opening will also make gate removal easier.
Make gates short, to prevent large pressure drops and avoid sharp angles between gates and runners, which could contribute to a pressure drop in the system. Make corners rounded, so that the melt flow is not inhibited. The cross-sectional shape you choose for the gate depends on the shape of the runners.
The gates are highlighted in the following diagram.
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