Electrically and/or thermally conductive metal-fibre filled articles - produced by screw injection moulding with formation of sec. boundary layer flow

摘要

Mfr. of plastics semi-finished and finished prods. having high electric and/or thermal conductivity, with addn. of metal fibres, comprises allowing the moulding cpd. to flow in plastics or liq. state through a screw and injecting it into a mould where it solidifies. Characteristically, the metal-fibre-filled plastics flows into the mould, whilst giving rise to a sec. boundary layer current along the rough(ened) walls of the tool cavity and is simultaneously strongly cooled. Used for mfr. of conductive machine components e.g. cogwheels for use in environments exposed to build-up of static charges. The thermally and/or electrically conductive filler is not displaced during the injection step i.e. it extends throughout the matrix. This was by no means ensured in prior-art processes where the matrix tended to form a solid skin with practically no-content of conductive filler, thus severely impairing the conductivity of the prod. The mould walls are roughened by sanding.