Casting Study: Toothed Wheel

This toothed wheel consists of two parts which are assembled with cast-in spigots and bolts in special steel. The parts are made in zinc alloy ZA-27, and apart from trimming, receive no machining or other finishing operations. The part is produced in two sizes, the largest of which has an external diameter of 238.5 mm. It drives pinions of a particularly complex reduction gear system. The parts have a maximum of reliability strength and precise operation. The main advantages received from the use of ZA-27 are: – the reduction in weight, thanks to the thin walls and relatively low density; – the avoidance of machining, thanks to the degree of tolerance which can be produced with zinc alloy pressure die casting; – the ease and speed of assembly, thanks to the excellent castability of zinc alloys enabling very complex shapes to be produced. These parts which have been produced for several years have never given rise to problems either in production or in operation, thus confirming once more the superiority of ZA-27 Alloy.