High pressure forming & thermoforming: Contouring film with speed and accuracy
There are two established processes for 3D forming: high pressure forming technology (HPF), which Covestro developed in collaboration with Niebling, and thermoforming.
In the HPF method, a printed film is clamped inside a forming tool and shaped in the region of its softening temperature by the sudden application of heated, compressed air at high pressure. With thermoforming, radiant heaters are used to heat the film well above its softening temperature. The film is then drawn by a vacuum and/or compressed air into a heated mold and formed. In addition, films may be contoured mechanically using punches or other specialized techniques.
The HPF method: Shaping for highly accurate positioning of symbols
In the HPF method, a printed film clamped inside a forming tool is shaped in the region of its softening temperature by the sudden application of heated compressed air at a pressure of 50 to 300 bar. This technique can be used to fabricate complex 3D geometries with our Makrofol® or Bayfol® films. One particular advantage of HPF is that decorative features and surfaces can be changed quickly during production. Critically, shaping is so precise that imprinted symbols, pictograms, letters or numbers remain precisely positioned – and this accuracy is another key advantage of HPF compared to thermoforming. HPF is also preferable for the processing of matte or textured films, because thermoforming can make matte films appear glossy and the process heat may damage textures. In addition, constant distortion that results from shaping can easily be compensated for by distortion printing. HPF technology is particularly effective for the mass production of 3D speedometers, fascia, dials, radio fascia and mobile phone front shells.
Thermoforming: For high draw ratios
In thermoforming, the film is heated by radiant heaters to well above its softening temperature, drawn by a vacuum and/or compressed air into a heated mold and formed. Compared to the HPF method, thermoforming allows a greater degree of stretching and improved forming precision, particularly at the corners of a component. This makes it especially well-suited to the manufacture of large-format parts. Thermoforming also works well for decorating film moldings with what are known as continuous design elements, where decorative features do not need to be positioned with pinpoint accuracy, as is the case with a burl wood or carbon design, for instance.