Here are some basic rules for gate and runner design, which, if you follow, will help you succeed with an injection mold design. Of course, there are almost endless applications for gates and runners, plus the wide array of materials can dramatically influence the design. A good tutorial, as mentioned below, can help with the molding of plastic parts by using the correct gate and runner.
Of course, any guide is only that: a guide. Combining basic principles with common sense and information about the material and molded part will provide all you need.
You can learn all you need to know about injection mold design with this tutorial. It covers everything from the most basic aspects to the detailed analysis of mold flow and cooling. Injection molding plastic parts can become quite frustrating, especially if the gates and runners are wrong!
The section on gates and runners is thorough and exhaustive. Every gate and runner you can imagine is clearly explained, so you know what to do, how to do it, and why ignoring gate and runner design in an injection mold is like building a house without considering how the occupants will enter and leave the house. Who would even consider this? Yet, the gates, runners and vents are often a matter of guesswork and luck. This can make all the difference for injection molding plastic parts.
Basic rules for gate and runner design
- When gating multiple cavities, always place the gates symmetrically in relation to the sprue.
- Round parts, such as gears, should be gated centrally. Use a diaphragm gate or three plate mold. This will ensure that the parts are balanced and round.
- Parts that are cup-shaped, such as capacitors, should be gated near the base. This will help avoid gas buildup and burning.
- Cosmetic parts or those that cannot show gate marks should be tunnel or submarine gated.
- Always gate into the part with the greatest wall thickness.
- Share these thing with the injection mold maker.
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