Casting Study: Ratchet Housing

The goal of product designers for the 1/4 in. air ratchet was to lower product manufacturing costs while improving performance and appearance. The original product design specified an axial assembly–a machined steel head attached by a lock nut to a housing handle. Extensive machining of the cast housing was required to incorporate the air drive mechanism. The improved design eliminated the lock/nut assembly by combining the head and handle into a two-piece longitudinally-split housing. By precision die casting the pieces in ZA-27 alloy, machining was reduced to just one drilling operation. ZA-27’s superior mechanical properties provide the ratchet with improved strength and rigidity. The design also improved air passage layout. As a result, a new one-piece air manifold was developed. Net-shape die cast in ZA-8, the manifold permits cast-to-size precision bores and reduces passage components by one-third. An advantage of using zinc for the application is enhanced sound suppression for quieter operation. Die casting provides additional design features such as cast-in logos and warning labels on the handle, and cast-in ”crush ribs”” for easy and secure assembly of the drive head parts. The new streamlined product is more attractive and comfortable to grip than it was previously.