Partner und Internationale Organisationen
(Englisch)
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StructoForm GmbH (D), Federal Institute for Materials Research and Testing (D), Eurocarbon BV (NL), Promolding BV (NL), Savoy Moulage SA (F), Sulzer Markets and Technology Ltd. (CH)
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Abstract
(Englisch)
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This abstract describes the main activities of Gurit Suprem, A Business Unit of Arova Schaffhausen AG, in the remaining project time after the Mid Term Assessment.
Material
Besides the continuous improvement of the impregnation process, further goals of increasing the variety and flexibility of the process could be obtained. The portfolio of processable materials was increased to several Polyamides (PA6, PA11, PA12) and Polyolefines (HDPE) as well as special grades of carbon fibers (1k, 3k, 6k, special intermediate and high modulus) and aromatic fibers (PBO, p-phenylene-2.6-benzobisoxazole) with evaluation of suitable process parameters. As a result of non-destructive and mechanical testing, a special porous surface for was developed. This based on a study on surface treatment of inserts for improving the bonding behaviour of inserts to surrounding matrix in the injection moulding process by sanding, porous surface or thermal treating.
Process & Machine
To achieve the processing and product flexibility and quality, additional heating systems, winder, off-hauls, cooling rollers and concentration measurement was installed. This results in a fast and economic production of inserts. Optimizing of vents, pretension, bath setup, magnetic valve, insulation and heat controller take part.
Trail with liquid moulding for online impregnation of dense and heavy braids having high fiber volume content with low viscous prepolymers were not satisfying. With the improved exiting process, several type of inserts were produced.
Rods & Profiles
Rods and thick profiles can be produced either in one or in two steps. Depending on the dimension of product, a process has to be chosen. Basically flat and narrow tapes were produced and guided together in a second rollforming step. Round shapes from 2 to 6 mm diameter and also 3-D-forms like W-Sinus or flat with round middle section can be easily produced with optimized tolerances. Step-pressing is not so suitable and expensive.
The mentioned small size carbon fibers allow very narrow and thin tapes and rectangular rods. Also the production of wide tape and start-up of pressing fabric with foils were successful. Cylindrical (open hole) inserts 'hollow cigars' were made out of impregnated braids or consolidated tapes/rods by overwinding for use in dog-bone test specimen, also in conical shape. Bearing rings processed in a winding-pressing process were used as bearings in injection moulded parts.
Postforming
To optimise the inserts for use in the cavity, a suitable postforming is sometimes required to achieve a adapted shape for mould requirements The advantage of reforming thermoplastic inserts due to the requirements of the final part allows an optimal adjustment and integration of additional functions, e.g. spacer at the ends (4-leg-design).
The postforming of profiles was tested by construction of a crimp tool for printing a special relief on the material (increase of geometric stiffness). Performing bending action a fiber buckling hast to be prevented.
Summary
A successful goal could be reached in developing of adapted and optimised thermoplastic composite inserts, suitable for use as reinforcing inserts / elements in injection moulded parts.
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