The Thermoforming Process

There are many terms to describe the process of converting plastic sheet into a 3 D 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 early days of plastic forming, a processor would manually control the heat, forming and cooling cycles. Cycle times were long and replication sometime difficult. The processors were true craftsmen. Today, UPPI's computer controlled, in-line thermoforming machines are the craftsmen. 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 a high quality products. Cycle time is repeatable, even after several million parts.

Forming of a Part

The first stage of the thermoforming process is to heat the sheet to a pliable, semi-soft state. 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. When the material requires assistance to reach the "hard to reach" areas on the mold, a plug assist is employed. The plug assist ensures proper distribution of material throughout the part. After a cooling period, the pressure box opens and the formed part advances to the cutting stage. At the cutting stage, the part is cut to the desired dimension. The formed part advances to the removal stage where the part is extracted from the sheet line and boxed for shipping. At UPPI the thermoforming process takes place within several seconds with extreme accuracy.

To learn more, go to our Design and Tooling page