The difference between vacuum forming & thermoforming.

The terms vacuum forming and thermoforming are usually interchangeable, however thermoforming is a more generic term and refers to a range of fabrication processing where a plastic sheet has been heated to its ‘plastic’ malleable state and then shaped using a mould.  The forming (pushing the plastic on to the mould) can be via vacuum or air pressure.

A male or female mould can be used. A male mould is the same shape as the object being formed, and the plastic sheet would be placed over it. A female mould forms the exterior of a shape and is the reverse of the object being made.

Once the plastic has cooled it will be permanently in the shape of the mould unless it is heated to a high temperature again.

Thermoforming can include pressure forming, vacuum forming and twin sheet forming.

Vacuum forming is a type of thermoforming.  The plastic is heated to it’s plastic, soft, malleable shape and placed over a mould.  Then the air is vacuumed out, sucking the plastic onto the mould.  Then the plastic is cooled back to a solid state, forming the new shape.  The air can then be blown back to free the plastic from its mould.

Here are some examples of vacuum forming.

Thermoforming is a term used in plastic engineering to cover a variety of processes.  All thermoforming involves heating a plastic sheet to its pliable plastic state.  Different plastics require a different temperature and length of heating to reach their malleable state.

Once heated the plastic is placed over an existing mould. Moulds can be made of a variety of different materials including MDF, aluminium, epoxy and foam. Then the plastic sheet is pushed or sucked around the mould to form the new shape.  This can be done via air pressure (pressure forming) or vacuum (vacuum forming).

Once the plastic cools it becomes solid again and will hold its new shape.  It can then be removed from the mould and a variety of finishes can be applied if necessary.  These can include different coatings, screen printing, lamination etc.

Thermoforming animation

Vacuum forming

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