Empty hole
Description
Easily seen "air wells" in transparent plastics, but can also appear in an opaque plastic. This is about the thickness, and often caused by plastic shrink from the center of injection molding parts.
Preview
Causes
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Possible causes
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Recommendations to resolve
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Injection molding machine
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1.Mold is not fully populated.
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1.Increase the amount of shot.
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2.Increase the injection pressure.
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3.Increase the screw forward time.
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4.Reduce the melting temperature.
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5.Decrease or increase injection speed. (such as amorphous class plastic increases 45 speed ).
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2.Valve is not function properly.
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Checks whether the valve dehiscence or malfunctioning.
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Mold
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1.Gate is too small.
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Increase the size of gate to prevent the plastic at the gate being solidified earlier.
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2.Flow path design or size is not correct.
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1.Use round or trapezoidal channel.
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2.Runner's diameter increase.
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3.Gate location error.
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Change the location of the gate, so plastic enter the thickest part of the mold. |
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Plastic
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Plastic contains too much water.
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1.Plastic dry for a long time to reduce the water content of plastics.
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2.Use a vacuum or desiccant dryer.
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