Content - Vacuum forming

Vacuum forming

Vacuum forming is a manufacturing process which reforms thermoplastic synthetics.

The raw material

The initial material for the manufacture of component holders is sheets of plastic, which are stacked in a special jig, lifted by suction cups and automatically fed individually to the vacuum forming machine.

The machine

The tool is located in a lower section of the machine. The plastic sheet is clamped between the tool and a heating device.

The production

Heating the sheet makes the material pliable. It is pulled over the tool by generating a vacuum. Finally the finished tray will still have to be sawn, milled or punched to size.

The background conditions

Vacuum forming tools are mostly made of aluminium. They do not have to stand up to the requirements of an injection moulding tool for long periods, and can thus be made in a shorter time. This is why in vacuum forming smaller batches are economically viable.

  1. Heating process
    A plate or sheet of thermoplastic material is fitted into a clamping frame and heated up to the plastic state using a suitable heat source.
  2. Start of forming
    Once the plate is mouldable due to heating, the radiators are retracted.
  3. Forming: Create overpressure
    The base-plate and the tool are lifted. A pump creates overpressure (pre-blowing).
  4. Forming: Create a vacuum
    The heated plate is pre-stretched using air pressure and the moulding tool is advanced to the pre-stretched plate. The air between tool and plate is sucked off (vacuum).
  5. Done!
    The atmospheric external pressure presses the soft plate to the walls of the mould in such manner, that the contours are exactly reproduced.