Laminated structure of an electric machine with cooling fluid flow paths

A laminated structure 18 of an electrical machine is disclosed, in which flow paths 19 for cooling fluid are formed between juxtaposed laminations 21, 22 by spaced protrusions 11. The spaced protrusions are formed as integral parts of the juxtaposed laminations and act as separators to space the juxtaposed laminations one from the other, a protrusion being formed at or near the end of a tooth 13. A surface 16 formed by each of the protrusions is domed to provide an aerodynamic surface and the interior of the protrusions may be filled with electrically insulating material. The protrusions may be formed by deep drawing using a pressing tool and die by a cold or hot working process (electric or friction heating). Alternatively the protrusion may be formed by a rotating tool having variable eccentricity.