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DEVELOPMENT OF DESIGN AND PROCESSING TECHNIQUES FOR OVERINJECTION OF THERMOPLASTIC COMPOSITES.

Objective

The aim of the project is to provide essential technological and theoretical tools for industrial applications of overinjection of short fibre reinforced thermoplastics into continuous fibre reinforced thermoplastics bases
The aim of the project is to provide essential technological and theoretical tools for industrial applications of overinjection of short fibre reinforced thermoplastics into continuous fibre reinforced thermoplastic bases. This research will lead to new capabilities in specifying a suitable heating system for the base such that the surface of the base will remain hot during the injection phase. An overinjection tool will also be designed with facilities for clamping and sealing the base. The project will also simulate the flow in a tool with a heated base fixed within the tool cavity, and consider the effects of processing conditions on the bond strength of an overinjected component. The project will conclude by design and manufacturing a real life overinjected product.
Sample overinjection items have been manufactured and analysed. 2 moulds producing different overinjected shapes have been designed, fabricated and commissioned. The thermomechanical properties of materials under consideration have been obtained experimentally.

The process parameters which effect the performance of items manufactured by the overinjection process have been identified. Those parameters which maximize the bond strength between base and overitem have been optimized. Parameters which decrease the formation of voids, decrease the amount of shrinkage and warpage have also been identified. The overinjection process can be successfully applied to the manufacture of industrial components, as demonstrated by the production of an industrial prototype.

The available software packages which attempt to simulate numerically the fibre flow during the overinjection process have several limitations. A number of these limitations have been overcome but the requirement for full 3-dimensional calculations has also been demonstrated.

An approach to the finite element modelling of the thermomechanical response of a thermoplastic during processing has been developed. The technique of varying the finite element mesh at different stages of the overinjection process appears to work satisfactorily.

The 2 major sources of defects to overinjected products are shrinkage and inadequate wetting of the base. However, these sources are not peculiar to the overinjection process but are generally associated with injection moulding. Consequently, solutions to these defects are to be found among those universally applied to injection moulding.

Particular attention has been taken to develop techniques that are applicable to a broad spectrum of applications. The commercial viability of the process has been demonstrated by successfully designing, fabricating and testing an industrial prototype.
An initial investigation into the potential market for overinjection has uncovered a number of suitable products.
This research will lead to new capabilities in specifying a suitable heating system for the base such that the surface of the base will remain hot during the injection phase. An overinjection tool will also be designed with facilities for clamping and sealing the base. The project will also simulate the flow in a tool with a heated base fixed within the tool cavity, and consider the effects of processing conditions on the bond strength of an overinjected component. The project will conclude by design and manufacturing a real life ovreinjected product.

Coordinator

Marine Computation Services Ltd
Address
Buttermilk Walk 3
90 Galway
Ireland

Participants (5)

Centre de Recherches Scientifiques et Techniques de l'Industrie des Fabrications Metalliques - CRIF/WTCM
Belgium
Address
Rue Des Drapiers 21
1050 Brussels
Fabrique Nationale Herstal SA
Belgium
Address
Voie De Liege 33
4040 Herstal
GERMAN AEROSPACE CENTRE
Germany
Address
Linder Höhe
51147 Koeln
University College Galway
Ireland
Address

90 Galway
École Nationale Supérieure des Mines de Paris
France
Address
60 Boulevard Saint-michel
75272 Paris