Apparatus and method for moulding articles

A mold for forming a wind turbine blade is formed in two halves, each half 1a comprising a sandwich structure of a perforated outer layer, an inner aluminum honeycomb structure and an inner impermeable heat-conducting layer. An article in the form of a mat of glass fiber impregnated with epoxy resin is placed in the mold. A supply chamber 6 supplies heated pressurized air to the mold which passes into the honeycomb core of the mold through the perforated outer layer, and back through the outer layer into two exhaust chambers 7. A row of supply conduits 13 and exhaust conduits 16 connect the exhaust chambers 7 to the supply chamber 6. The air in each conduit 13, 16 is heated by a respective heat exchanger 18 supplied with heated water 9. The heated air cures the epoxy resin, and the mold is then cooled by supplying cold water to the heat exchangers 18, which, in turn cools the air supplied to the mold. The water used to cool the mold is then re-used for the subsequent heating of another article placed in the mold, in order to save energy. Alternatively, the article in the mold may be cooled using a separate supply of air which is not cooled in the heat exchangers 18.