Patent ID: 7090800

Claim:
A method of injection compression moulding a thin walled article using a mould, the method comprising: mounting a core, surrounded by a rim closure part, on a pressure plate so that the core is movable separately from the rim closure part and separately from the pressure plate in a direction of opening and closing of a mould; moving the pressure plate relative to a first mould part between a first end position and a second end position in which the mould is respectively opened and closed, wherein the first mould part, the core and the rim closure define a mould cavity having a thin walled portion; injecting a predetermined dose of molten material into the mould cavity; and applying a force to urge the core away from the pressure plate towards a position of minimum mould cavity volume while molten material is being injected into the mould cavity, the force being such as to permit the mould cavity volume to be increased by injecting the molten material and such that upon termination of the injection of the molten material into the mould cavity, the mould cavity is only partially filled therewith, the thin walled portion of the mould cavity remaining unfilled; wherein, prior to reaching the second end position, the pressure plate makes direct contact with the core to reduce the mould cavity to its minimum volume, a compression force being directly applied to the core as the pressure plate is moved towards the second end position to cause the molten material to flow so as to fill the mould cavity entirely including the thin walled portion.