Injection mold gating system consist of sprue, runner, gating point, through gating system, the melted plastic materials are pushed into the mold cavities, this is the first step of injection molding process, an optimum gating system design would have to consider the sprue, runner cross-sectional shape and measurement, gating location, gate measurement.
There are a few basic principles to follow when you design gating system for a plastic injection tooling.
When using point gate, ensure that the runner can be trimmed off automatically by de-gating design.
Proper location of the gate point will be directly affect the quality of the injection molded parts gate location selection should follow the following principles:
- Gate location should be chosen in parting surface, so that it would be easier for machining and maintenance.
- The runner should be designed even, mold flow distance and sectional size in balance can achieved stable molding quality.
- Gating location should be on the thick-wall area so it ensure the cavity can be filled completed.
- The mold flow should not be right on the inserts or lifter, high pushing pressure of melt flow would probably deform the inserts.
- Try to avoid weld marks or weld lines created in the critical surface, changing location of gating and try to make the weld line on uncritical surface.
- Consider the venting when design the gating, make sure the end of the mold flow have good venting.
- Gates should be easily removed and gate mark should not affect the appearance of the molded parts.