Vacuum forming of plastics
In vacuum forming, a heated thermoplastic sheet is pressed against the mould by a vacuum. The result is a formed part that reproduces the mould’s shape exactly. Our production plant in Vantaa has five vacuum-forming machines, which can be used to produce items of varying sizes. Our largest machine has the forming area of 1,800 X 2,800 mm.
The process involves heating a plastic sheet with the plastic forming machine’s electric resistors. Once the plastic has reached its forming temperature, air pressure is applied to stretch it to a bubble. The tool table containing the mould is simultaneously raised so that the mould is placed inside the bubble. Then, air is sucked out of the bubble through the introduction of a vacuum, after which the item is cooled and released from the machine. To complete the process, excess material is trimmed off, and any necessary holes or slots are drilled in the formed part by means of CNC technology.
The moulds used in vacuum forming can be made from a variety of materials, such as wood, aluminium or polyurethane resin (for example, ebalta materials, Cibatool or SikaBlock). The choice of mould material depends on the quality required of the end product and the batch size.
Materials used for vacuum forming
Numerous thermoplastics are suitable for use in vacuum forming. Some plastics (such as PC, PP) must be pre-heated before the actual vacuum-forming process Sheets used for vacuum forming usually range from 1 to 10 mm in thickness.
The most commonly used materials: