Process for the manufacture of an injection mould

Process for the manufacture of a hot runner manifold for injection moulds, in which the system of channels lies in one or more planes and heating is effected by a system of pipes which is substantially heat insulated against the outside, characterised in that when the hot runner manifold lies in n planes one above the other (n=1, 2, 3, . . . ), a composite body is produced from at least n+1 plates (11,12,13) and the channels (2) through which the molten material is to flow are formed in the internal surfaces (F2, F3) at which the plates are to be joined together while channels (10a) for the insertion of tubular heating elements (10) are worked into the external surfaces (F1, F4) of said plates, which channels may be covered to separate them from the outside by further plates (9,9'), whereupon the surfaces which are to be joined together (F1, F2, F3, F4) are freed from impurities and the plates are then joined together by diffusion welding.