Banana gate of plastic injection mold runner system design

In order to get the best injection quality, the gate type must be selected carefully, the coommon gate tyeps are: direct gate, side gate, pin-point gate, sub gate,valve gate of hot runner etc. Among them, the side gate is divided into tab gate, ear protection gate, fan gate, thin gate and so on, the sub gate is divided into sub gate, banana gate, downturning gate and so on.

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According to the production automation, it is divided into manual removal and automatic removal, the side gate and direct gate are need to be manually removed after production,but the sub gate and pin-point gate and valve gate of hot runner are automatic removed.

Banana gate: the banana gate is evolved from the sub gate (as shown in picture 1), because it is shaped like the horn of a cow, it is also commonly known as the sub gate, it has a similar hold to the sub gate, the difference is that the processing of the banana gate is more complicated, and it is generally necessary to make a gate insert (as shown in picture 2), the opening of the mold elbow can automatically pull off the gate and the gate position, and also the banana gate can only enter the core, and cannot be made on the side of the product like a sub gate.

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Advantage:

1. The gate can be cut off automatically, eliminating the secondary processing and realizing automated production;

2. The position of the gate is big, and the position of the gate can be set freely on the outside or inside of the product;

3. The gate is small, which has little effect on the appearance of the product, and somesub gates are hard to see with eyes;

4. The mold structure can be simplified, for some products with high appearance requirements, if you use the pin-point gate, we must use a three-plate mold to realize it, but we only need to make tw-plate mold if changing to sub gate which can reduce the complexity of the mold structure, but also reduces the mold thickness and saving mold cost.

Disadvantage:

1. Large pressure loss, because the sub gate is generally relatively small, usually in the range of Ø0.8~2.0mm, when the plastic passes through the small ggate, a large part of the pressure will be lost;

2. The processing is more complicated, such small gate generally need to make gate inserts;