VACUUM FORMING (Male and Cavity Moulds)
…is the most basic of the thermoforming processes. The advantages over other plastic processes are the relatively low tooling cost and short lead-times required to produce large, thick walled mouldings.
Moulds can be constructed from wood for proto-typing, small production runs and where the material used has a low forming temperature. Epoxy resin and Aluminium filled epoxy moulds are used for longer production runs. Aluminium moulds are used on cavity moulds where surface finish and mould cooling is required. When the plastic sheet is at the forming temperature, it is sufficiently pliable that a mould can be pressed into it. Uniform pressure is applied in the form of vacuum to bring the sheet into full contact with the mould. The formed article is kept on the mould until the material cools to below heat distortion temperature.
HIGH PRESSURE THERMOFORMING
…should be considered when sharp detail is essential. Based on the vacuum forming principal it gives us the ability to provide a higher degree of definition on the external surface of the formed article. Features such as tight radii, styling lines, stiffening ribs, surface texturing, undercuts and embossed logos or lettering become entirely possible using this advanced process. The mould is also heated to the operating temperature and uniform pressure is applied in the form of BOTH vacuum and positive pressure to push the sheet into full intimate contact with the mould surface. Thus achieving far greater definition.
SNAP BACK MOULDING
…allows for prestretching of the material for more even thickness distribution. The material is heated to forming temperature and then moved by vacuum or compressed air into a bowl shape about two thirds the height of the finished part. When the bubble is at the correct height the mould is forced into it and the material is snapped back against the mould.