Thermoforming (plastic)

Thermoforming is a Forming process for thermoplastics. It is also referred to as hot forming, Deep-drawing and vacuum deep-drawing. It is used in the manufacture of Plastics such as PVC, PET, PS and PP - often instead of Injection moulding. Depending on the semi-finished product used (films or sheets), there are various processes using different moulds.

Films are fed into, and guided through, the automatic forming machine by toothed chains at the edges of the film web. While inside the forming machine, they are first heated on one or both sides in a heating station. During subsequent transport, they are drawn apart slightly to stop them sagging. A pre-stretcher and thermoforming mould define the contour in a frame and the film is then formed in a mould using compressed air and/or a vacuum. As soon as the film has cooled, it is removed from the mould and can be transported to the subsequent Work steps.

The forming process for sheets is similar to that for films but also involves stretching (reducing the wall thickness through elongation) and undercutting.