The gas of the bubble (vacuum bubble) is very thin and belongs to the vacuum bubble. In general, if a bubble is found at the moment of mold opening, it is a gas interference problem. The formation of vacuum bubbles is due to insufficient filling or low pressure. Under the rapid cooling of the mold, the fuel at the corner of the cavity is pulled, resulting in a volume loss.
Solution:

(1) Increase the energy of injection: pressure, speed, time and amount of material, and increase the back pressure to make the filling full.

(2) Increasing the temperature of the material flow smoothly. Lower the material temperature to reduce shrinkage, and appropriately increase the mold temperature, especially the local mold temperature at which the vacuum bubble is formed.

(3) The gate is placed in the thick part of the part to improve the flow of the nozzle, runner and gate, and reduce the consumption of press.

(4) Improve the mold exhaust condition.

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