Venting moulds

摘要

The outlet, for a mould chamber with a wall (2) made from one or more materials and having a moulding surface (20), comprises an aperture (3) which passes through the wall from the moulding surface, allowing the mould chamber to connect with the outside atmosphere. The aperture is closed by an insert (1) which is shaped so that it completely seals the aperture when fitted into place and lies flush with the moulding surface (20). The end face (11) of the insert has an area of less than 100 sq. mm. and pref. less than 10 mm<2>. and it is made from a material which is substantially less hard than the material of the mould chamber wall (2).