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A hot hollow tube of thermoplastic material is dropped from an extruder. This tube is usually called parison. |
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The parison is then captured in the closed chamber of a divided mold which seals one end of the parison and leaves the other end open. |
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Compressed air is injected through the open end of the parison. The parison is expanded like an inflated balloon.
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Compressed air continues to blow in until the parison reaches the wall of the mold. The hollow parison now conforms to the shape of the mold cavity. |
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The molded plastic stays in the mold until it cools and hardens. Once released from the mold, further handlings such as rimming and trimming can be performed. |