Abstract: A cast-formed bi-metallic worm assembly of a mechanical screw press for expressing liquids from fibrous materials and a method of manufacture therefor. The worm assembly is rotatably driven by the press drive shaft and includes an outer flight body having an integral outwardly extending helical flight formed of a relatively brittle, wear-resistant homogeneous cast material and an inner hub tightly fitted and substantially fully mated within, and coextensive with, the outer flight body. The inner hub, cast formed of a more ductile, tougher homogeneous material, includes a hollow cylindrical interior surface structured for slidable engagement around and in driving connection with the drive shaft. The inner hub and outer flight body are securely engaged one to another by a very thin layer of bonded brazing compound over substantially the entire mating surface therebetween. The method of manufacturing helps insure very close mating surface contact to enhance the strength of brazing.