Manufacture of waveguide parts by investment casting from frozen-mercury patterns

The paper explains and discusses the capabilities and limitations of the recently developed frozen-mercury process for the production of cast parts. Many types of waveguide, including bends, horns, mixers, etc., are currently being manufactured, and some of these incorporate structural support features. As flanges are cast on, the only finishing necessary is the machining of the flange faces, including any choke grooves and the drilling of fixing holes. Cast complex horns containing transfer sections have proved particularly valuable as they are very difficult to produce by fabrication techniques. The waveguide parts are cast in aluminium alloy, gunmetal or other alloys, according to requirements. Consistency of dimensions in relationship to design tolerances are examined. Typical examples are described in the paper and tolerances and surface finish obtainable discussed.