Faster, more predictable die casting

Alloys of zinc and magnesium sport a wide range of physical and mechanical properties. The result is enormous flexibility in selecting die-casting materials for small, complex components. Designers have a broad latitude of materials to choose from for small die-cast components. Each of five zinc alloys, plus a magnesium option has strengths and weaknesses for particular applications. But as die-casting mediums, they have an advantage over materials such as aluminum. Their dimensional stability and predictable shrinkage rates ensure part-to-part consistency while low thermal mass permits high cycle rates. And designers often see a tenfold increase in die life thanks to the low abrasive wear rates of these alloys when compared to their aluminum counterparts. Special die-casting techniques let designers easily modify designs to boost structural properties. To improve creep resistance in a component with external or internal threads, for example, designers can increase thread count. Special hot-camber die-casting processes produce 360* external threads cast up to 50 threads/in. (20 threads/cm). Die casting lets the parts meet a thread tolerance class of 2A (6g) with no secondary deburring or chasing. Similarly, uniform wall thicknesses in a design distribute stresses more evenly. And precision tooling used in hot-chamber die casting helps eliminate secondary finishing or machining -- net-shape parts exit the mold "flash-free." Net-shape manufacturing is one of the main advantages of this die-casting method as it reduces material waste and part cost. The most common zinc alloys for hot-chamber die casting are Zamak 2, Zamak 3, Zamak 5, ZA-8, and ACuZinc. Overall, their mechanical properties compare favorably with brass and screw-machined steel. Zamak 3 is the most widely used zinc alloy. It offers the best combination of mechanical properties and economics. Zamak 2 and 5, with higher copper content, better resist wear. In addition, Zamak 5 offers higher creep resistance, while Zamak