1. Arrange the 7 steps below in correct order to form the typical practical injection molding sequence:
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Plastic raw material is stored in the hopper
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When enough melted plastic has accumulated ahead of the screw, the screw stops rotating
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It is conveyed forward by the flights of the screw and is gradually melted as it moves forward
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The plastic goes through the nozzle, sprue, runners, gates and on into the mold cavities
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Packing occurs – a little more plastic is forced in after the cavities are full
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The plastic falls on the rotating screw
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The screw, acting as a plunger, pushes the melted plastic out of the injection barrel
2. What are the four functions of the mold?
3. What are baffles and bubblers?
a.
Cooling devices used in recessed areas in the mold (for example deep cores) to cool plastic.
b.
The small flow passage at the end of the runners that allows plastic to flow into the mold cavities.
c.
None of the above
Answers
Question 1
Here is the correct order of the steps:
Plastic raw material is stored in the hopper.
The plastic falls on the rotating screw.
It is conveyed forward by the flights of the screw and is gradually melted as it moves forward.
When enough melted plastic has accumulated ahead of the screw, the screw stops rotating.
The screw, acting as a plunger, pushes the melted plastic out of the injection barrel.
The plastic goes through the nozzle, sprue, runners,gates, and on into the mold cavities.
Packing occurs – a little more plastic is forced in after the cavities are full.
Question 2
1. Provide flow passages for the plastic to quickly fill cavities
2. Provide for escape of air from the cavities
3. Cool the plastic
4. Provide a way to eject the molded parts
Question 3
A
March 26, 2007
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