Moulding machine and process for forming a mould

A moulding machine comprising first and second non-complementary moulds, the first mould defining a female mould cavity and the second mould defining a flat moulding surface, wherein the first and second moulds are movable between a first position in which the moulds are apart and the female mould cavity and the flat moulding surface both face upwards, and a second position in which the moulds are brought together and the flat moulding surface faces into and closes the female mould cavity to form a completely enclosed cavity, and wherein each mould has a plurality of bores formed through it with an opening at each end configured for receiving flow of a mould cooling or heating fluid, and at least two of the bores are connected to each other by a block over the opening at one end of one bore and the opening at the end of another bore, the block having a mould facing surface and being formed with a groove defined on the mould facing surface which connects the openings to each other, wherein the or each groove is formed with a first end, a second end, and a constriction therebetween such that the flow path of the or each groove first narrows and then widens again between the first end and the second end, the constriction being configured to provide a venturi effect so that when the fluid passes through the constriction its velocity increases.