Material Roll - Where the thermoforming process starts.

PET sheet formed to shape coming out of the mouth of a thermoforming machine.

Thermoforming process overview.

It is the reshaping of thermoplastic forming materials at increased temperatures into molded articles. Forming techniques start with a pre-form usually in the shape of a sheet or a film. The thermoplastic sheet is heated until it is soft, formed against a colder mold.

The sheet is held against the mold by pressure / vacuum until the part is rigid. The formed part is then ejected from the mold and pre-cut from the rolled sheet. Final formed part is then sent to another process called cutting or trimming (can be inline or offline) where it is separated from the excess plastic surrounding it.


There are several categories of thermoforming, including vacuum forming, pressure forming, twin-sheet forming, drape forming, free blowing, and simple sheet bending. But three are being used by Primepack:

  1. VACUUM FORMING - is a plastic thermoforming process that involves forming thermoplastic sheets into three-dimensional shapes through the application of heat and pressure. In general terms, vacuum forming refers to all sheet forming methods, including drape forming, which is one of the most popular. Basically during vacuum forming processes, plastic material is heated until it becomes pliable, and then it is placed over a mold and drawn in by a vacuum until it takes on the desired shape.

  2. PRESSURE FORMING - This process is similar to vacuum forming, except with the addition of pressure, which pushes the sheet into the shape of the mold. This process is mainly used for parts that require styling and aesthetic qualities because pressure forming creates greater detail, allowing for textured surfaces, undercuts and sharp corners, which are not as easily created with vacuum forming.

  3. PLUG ASSISTS FORMING - is a widely used forming technique and requires the use of a female (cavity) mold. The limited depth of draw of female molds is improved by the use of plug assist.
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