vacuum molding

materials technology

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July 14, 2026

Quick Summary

Vacuum molding, also known as vacuum forming, is a manufacturing process used to shape plastic materials. In this technique, a sheet of thermoplastic is heated until it becomes pliable. This heated sheet is then pulled by vacuum into contact with the cold surface of a mold. As the plastic cools and solidifies against the mold, it takes on the mold's shape, creating a dimensionally stable finished product. This method is used to produce items like cups for cold drinks from materials such as polystyrene or PET. Vacuum forming is a variation of sheet thermoforming, and it differs from blow molding in that it starts with a sheet rather than a tube.1

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plastic
Thermoforming and cold molding
…sheet can be pulled by vacuum into contact with the cold surface of a mold, where it cools to below T_g or T_m and becomes dimensionally stable in the shape of the mold. Cups for cold drinks are formed in this way from polystyrene or PET.
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…sheet can be pulled by vacuum into contact with the cold surface of a mold, where it cools to below T_g or T_m and becomes dimensionally stable in the shape of the mold. Cups for cold drinks are formed in this way from polystyrene or PET.
Read More