Casting Study: Regulator

The regulator for Turner’s self-igniting torch has a design criteria specifying pressure tightness, strength, cleanliness and metal-chip free, net shape and cost-effective manufacturing. A screw-machined aluminium or brass regulator was first considered, but ruled out due to excessively high machining cost. Another factor that weighed against screw matching was the resulting metal chips. Turner engineers finally settled on a state-of-the-art zinc die cast regulator. What makes the zinc die cast regulator unique is its complex coring. The core is actually two cores joined in the middle of the regulator, forming a step. Another design feature of the zinc regulator is the use of express threads, which are formed in the regulator’s inlet sleeve after the part is cast. This clean, chip-free technique forms threads easily in the ductile zinc without breaking the casting’s skin. This process actually forms stronger threads than would result from cutting. In addition, it eliminates the risk of porosity resulting from breaking the casting’s skin.