Centre for Applied Research of the Faculty on Digital Media & Creative Industries

Vacuum vormer

Modelling with a vacuum!

Vacuum forming, also known as thermoforming, is a process by which three-dimensional objects can be made out of flat materials. The material has to be an impermeable thermoplastic such as polystyrene, PET or PVC.

The material is warmed by an infra-red heater to a temperature at which it becomes pliable. A mould is then pressed into the material and the air between the mould and the material sucked out. The resulting vacuum allows atmospheric air pressure to push the plastic material closely against the mould. As the plastic cools off it keeps its new shape, corresponding to the details of the mould. Almost all plastics that soften when heated (so-called ‘thermoplastics’) can be used for vacuum forming.

The vacuum forming machine can also be used to give reliefs to synthetic fabrics. Synthetic fabrics are seldom impermeable, but they can be layered between the mould and a plastic sheet. Adding relief to a synthetic fabric in this way is a bit of an experiment; it is impossible to know in advance what the actual result will be. However, gauze and mesh-type fabrics generally give the best results.

To give a three-dimensional shape to a sheet of plastic or synthetic material you will need a mould. You can make your own mould, or use any suitable object. The mould has to meet a number of requirements:

  • it has to be made of a material that retains its shape when heated (to a maximum of 200°C). Expanded polystyrene, for instance, is not suitable;
  • it has to have a certain rigidity. A cardboard box, for instance, will collapse under atmospheric pressure, but a Lego brick will keep its shape;
  • to prevent the mould from being ‘wrapped’ by the plastic sheet, it has to have a ‘releasable’ shape. Think, for instance, of the difference between a bar of chocolate (releasable) and a muffin (non-releasable). The sides of the mould can be vertical (90°) up to 5mm in height, but above that point the sides have to have a ‘draft angle’ of 80° or less;
  • suitable materials to use when making your own mould include plaster, MDF or clay. A laser cutter can be used to cut out simple shapes that can also serves as moulds.

Would you like to vacuum form? Then come to the Makers Lab. One of the employees will instruct you how to operate the vacuum former. This will take about twenty minutes.

  • Bring your own materials, or make use of the (limited) supplies in the Lab
  • For plastic sales locations see this page

Published by  Centre for Applied Research FDMCI 3 October 2023