The process of zinc die casting involves a time-proven technology. As a material, zinc is extremely fluid, rendering it very useful for die casting. Zinc also offers excellent strength (~32,000 psi) compared to conventional aluminum 380 and magnesium (~23,000 psi).
Specific grades of zinc produce castings with yield strengths in excess of 57,000 psi.
While standard zinc castings can offer Brinell hardness of 82 HB compared to 80 HB for aluminum and 63 HB for magnesium, there are grades of zinc that can produce alloys in the range of 120 HB resistance, an increase in hardness of approximately 50 percent. Depending on the grade used, zinc alloys offer high strength with a high degree of creep resistance.
Because zinc is the most fluid of all die casting alloys, zinc die castings can be made thinner than with other metal alloys. Their shapes can be more intricate without the need for secondary machining. This makes zinc an ideal casting material for “Net Shape” or “Zero Machining” production.
The higher cycle times available with zinc die casting can result in significant production savings. Zinc castings also utilize the hot chamber die casting process, capable of yielding four to five shots per minute. This compares favorably to aluminum die casting, which typically yields half that level of productivity.
Zinc is die cast at around 400°C (750°F) compared to the cast temperature of 600°C (1050°F) that is required for aluminum. This lower casting temperature results in energy savings that lower the production cost per piece.
A lower cast temperature also increases tool life by 5-10 times compared to aluminum or magnesium casting production. Regardless of the volumes or complexity of the castings being produced, zinc consistently outperforms aluminum and magnesium in both casting production cost effectiveness and tooling amortization costs.
Another benefit of zinc comes from its compatibility with a variety of surface coatings. Zinc castings can be anodized, painted, powder-coated, Teflon- and E-coated, nickel-plated or chromated, making zinc more versatile than aluminum regarding the types of coatings that can be applied.
Alloys and Applications
MES has developed working relationships with a number of die casters in India and China. MES has sourced [nearly/over] 30 different zinc casting components from these producers in the last 18 months. Alloys include Zamak 3 for North American applications as well as Zamak 5, which is preferred by European customers.
Applications for these zinc alloy castings include flanges, connectors, duct plates, automotive components and housings for electrical products, machine tooling, meters, valves and actuators. These zinc castings are used with products in electrical, telecom, automotive and hydraulic applications.