Forming TEPEX® into components TEPEX can readily be formed into three-dimensional
products. The fundamental stages involved are heating the semi-finished
article, 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.
Diaphragm method
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 semi-finished article
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 sheet-type semi-finished articles
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.
Hybrid moulding 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.
