Injection moulding of functional cavities

A process of injection moulding a part with a functional cavity including the steps of;

• providing a mould assembly comprising at least a first mould portion and a second mould portion which when joined together define a cavity for moulding the part, at least one of the first and second mould portions having an opening therein for allowing injection of a mouldable material into the cavity, a first recess in at least one of the first and second portions, the first recess being to receive a first hollow tubular insert intended to be placed in the mould assembly before the injection of a mouldable material into the cavity and to remain in the part after moulding, a second recess spaced apart from the first recess in at least one of the first and second portions, the second recess being to receive a second hollow tubular insert intended to be placed in the mould assembly before the injection of a mouldable material into the cavity and to remain in the part after moulding and a gas supply arrangement to supply pressurised gas to the first and second hollow tubular inserts during the injection process;
• mounting a first hollow tubular insert into the first recess in the mould assembly;
• mounting a second hollow tubular insert into the second recess in the mould assembly;
• injecting a mouldable material through the opening into the cavity;
• injecting a gas under pressure through the first and second hollow tubular inserts into the cavity;
• and
• allowing the mouldable material to cool before opening the mould portions to release the moulded part with the first and second hollow tubular inserts retained in the moulded part and opening into the functional cavity;
• whereby to allow fluid connection between the first hollow tubular insert and the second hollow tubular insert via the functional cavity.