Thermoforming Process

There are many terms to describe the process of converting plastic sheet into a 3D shape or package. Examples of this terminology are: thermoforming, pressure forming, and vacuum forming. All plastic forming processes are a function of heat, vacuum and pressure.

In the beginning, a processor would manually control the heat, forming and cooling cycles. Cycle times were long and replication was sometimes difficult. Today, computer controlled, in-line thermoforming machines are used, and under the guidance of our technicians, the automated thermoforming machines take the guesswork out of what temperature is necessary, amount of vacuum and pressure required to manufacture high-quality products. Cycle time is repeatable, even after several million parts.

The Process by UPPI

  • Stage One: heat the plastic sheet to a pliable, semi-soft state
  • Stage Two: When the material is heated just right, the pressure box clamps the material to the mold, air is vacuumed from the closed tool, and the material takes the shape of the mold
  • Stage Three: Sometimes the material requires assistance to reach the “hard to reach” areas on the mold, so a plug assist is employed. The plug assist ensures proper distribution of material throughout the part
  • Stage Four: After a cooling period, the pressure box opens and the formed part advances to the cutting stage
  • Stage Five: At the cutting stage, the part is cut to the desired dimension
  • Stage Six: The formed part advances to the removal stage where the part is extracted from the sheet line and boxed for shipping

At Universal Protective Packaging, Inc. (UPPI), the thermoforming process takes place within several seconds with extreme accuracy.


UPPI is a worldwide developer, manufacturer and marketer of specialized, custom thermoformed plastic packaging. Our business is the design, creation, and production of effective, yet cost-efficient packaging for the retail, medical, electronics, industrial, and food industries. If you would like to learn more about our services, please do not hesitate to contact us.

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