Forming TEPEX® into components
TEPEX® can readily be formed into three-dimensional products. The fundamental stages involved are heating the composite sheet, forming and cooling in the mould, then removing and possibly finishing the product. Heating by means of infrared radiation is the preferred method, but contact heating is also possible. Depending on the complexity of the component, a number of forming techniques are available.
This is the most economical method of producing simple components requiring a minor degree of shaping. The fibre-composite sheet is placed between two barrier films, then both heated and formed within this sandwich, as illustrated in the diagram. The composite sheet is pressed against the walls of a positive or negative mould by means of a rubber diaphragm pressurised at approx. 5 bar. The component can be demoulded once it has cooled down sufficiently; the cycle times lie between 30 and 50 seconds. This method is used e.g. to manufacture footwear components.
Forming with rubber and metal moulds
More specialised mould technology is required for more complex components involving a higher degree of forming. As with forming sheet metal, upper and lower moulds are used; the male mould may be made from either rubber or metal. Forming with rubber moulds has proven to be highly advantageous, as it assures an even distribution of pressure within the cavity. To avoid wrinkling, the composite sheet must in addition be clamped by a special device during the deep-drawing process.
Depending on the thickness of the material and the degree of automation of the plant, cycle times of between 15 and 50 seconds can be achieved with this method.
Forming of TEPEX® flowcore
The special structure of TEPEX® flowcore allows the material to flow during the forming process. This permits a degree of variation in the wall thicknesses and volumetric filling of the cavity, with the result that no finishing of the parts is needed. Metal moulds with shear edges are used in this technique. The cycle times achieved are again between 30 and 50 seconds.
TEPEX® materials offer a new and exciting possibility for the further enhancement of injection mouldings and Long Fibre Thermoplastic (LFT) and Glass Reinforced Thermoplastic (GMT) compression mouldings. Injection moulding and GMT/LFT structures can be reinforced locally by using TEPEX® inserts. Applications designed with TEPEX® can be manufactured with complex local design details. The TEPEX® reinforcement can be introduced as a heated flat sheet or as preformed part. During moulding the materials fuse together and form a highly integrated part. The injection moulding or GMT/LFT polymer is typically of the same family as the TEPEX® matrix material, ensuring a good weld bond. The processes are state of the art.