The Advantages of zinc die casting alloys

TODAY'S ZINC DIE CASTING ALLOYS are strong, durable and cost effective engineering materials. Their mechanical properties compete with and often exceed those of cast aluminum, magnesium, bronze, plastics and most cast irons. There are two basic categories of zinc die casting alloys: ZAMAK alloys and ZA alloys. The ZAMAK alloys are by far the most widespread in terms of usage. Specifically, the #3 alloy (ASTM AG40A, SAE 903) is the most used general purpose alloy in North America for hot chamber pressure zinc die casting. It provides an excellent combination of strength, ductility and impact strength, as well as offering superior finishing characteristics for plating, painting and chromate treatments. The Benefits of Zinc Die Cast Products are: Less material is required. Zinc's superior casting fluidity, strength and stiffness permits the design of thin wall sections for reduced weight and material cost savings. Faster production and extended tool life. Die casting production rates for zinc are much faster than for aluminum, or magnesium primarily due to the lower casting temperatures of zinc. The lower temperatures also result in less thermal shock and therefore extend the life of zinc die cast tools in excess of 1 million shots or approximately 10 times greater than aluminum dies. Machining operations are reduced. Due to the superior net-shape casting capability of zinc alloys, machining can be eliminated or drastically reduced. Assembly operations are reduced. Entire assemblies can be cast as a single unit, eliminating the need for expensive assembly operations. Eliminate bearings and bushings. Zinc's excellent bearing and wear properties allow greater design flexibility and can reduce secondary fabrication costs by eliminating small bushings and wear inserts.

Zinc Alloy Properties Alloy Zamak #3 Zamak #5 ZA-8         Mechanical Properties Die Cast Die Cast Die Cast Ultimate Tensile Strength: psi x 103 (MPa) 41 (282.7) 48 (328.0) 54 (374) Elongation: % in 2" 10 7 6-10 Shear Strength: psi x 103 (MPa) 31 (213.7) 38 (262.0) 40 (275) Hardness: Brinell 82 91 95-110 Impact Strength: ft-lb (J) 432 (58.3) 482 (65.1) 313 (42) Fatigue Strength Rotary Bend - 5 x 108 cycles psi x 103 (MPa) 6.9 (47.6) 8.2 (56.5) 15 (103) Compressive Yield Strength - 0.1% Offset: psi x 103 604 (413.7) 874 (599.8) 37 (252) Modulus of Elasticity - psi x 106 (MPa x 103) 12.46 (85.5) 12.46 (85.5) 12.47 (85.5)         Physical Properties       Density: lb/cu in (g/cm3) .24 (6.6) .24 (6.6) 0.227 (6.3) Melting Range: oF (oC) 719-728 (381-387) 717-727 (380-386) 707-759 (375-404) Electrical Conductivity: % IACS 27 26 27.7 Thermal Conductivity: BTU/ft/hr/oF (W/m/hr/oC) 65.3 (113.0) 62.9 (108.9) 66.3 (114.7) Coefficient of Thermal Expansion 68-212oF in/in/oF (100-200 oC m/mm/oC) 15.2 (27.4) 15.2 (27.4) 12.9 (23.3) Specific Heat: BTU/lb/oF (J/kg/oC) .10 (418.7) .10 (418.7) .104 (435.4) Pattern or Die Shrinkage: in/in .006 .006 .007         Chemical Specifications (per ASTM)(% by weight) Casting Casting Casting AI 3.5-4.3 3.5-4.3 8.0-8.8 Mg .02-.05 .03-.08 .015-.030 Cu .25 max* .75-1.25 .8-1.3 Fe(max) .10 .10 .075 Pb(max) .005 .005 .006 Cd(max) .004 .004 .006 Sn(max) .003 .003 .003 Ni(other) - - - Zn Balance Balance Balance         Industry Standards Casting Casting Casting ASTM B86-88 AG40A B86-88 AC41A B791-88 SAE J468B 903 J468B 925   UNS Z33520 Z35531 Z35636

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