Vacuum Forming, also referred to as thermoforming, is the manufacture of plastic components through a pressure forming process. Vacuum forming is performed by using a thermoplastic sheet. The sheet is heated to a flexible state and then placed over a mold and drawn into the mold to the desired shape of the finished part.
Just like roto-molding, vacuum forming is performed in steps, but that is where the similarities end. The first step in vacuum forming is creating a master pattern to produce the mold. The pattern and its framework are constructed to shape the outside of the mold. A variety of materials can be used to form the mold. Once the mold has set, it is then mounted on a back plate and vacuum holes are drilled through the mold and around the outside edge of each pattern. This allows the heated plastic sheet to be pulled completely over the mold to ensure a perfect part.
After all the preparations of the mold have been completed, the manufacturer is then ready to perform the actual vacuum forming process. The plastic sheet is placed over the mold and clamped into place. The plastic sheet is heated and a vacuum is applied from beneath the mold. The heated plastic is then drawn into the cavity. After the plastic has been allowed to cool, the clamps are taken off and the newly formed parts are taken from the mold. The final step is to then cutout the individual molded parts and remove any sharp edges or corners.