Engineering characteristics that answer your most critical needs.
Generally, zinc die casting tolerances are superior to those of aluminum and magnesium die castings. Zinc die casting can produce repeatability of less than ±0.001" for small components, often rivaling machining tolerances. Few other processes can easily achieve the same net shape performance. Many components are die cast to net shape and require no further machining.
In general, zinc alloys machine rapidly, with minimal tool wear. Machining rates often rival those of free machining brass, and can be three times faster than for influences the selection of ZAMAK and ZA alloys over competitive materials.
Thin Wall Capability
Exceptional casting fluidity is displayed by all ZAMAK and ZA alloys, which provides superior thin-wall castability, regardless of the casting process employed. Wall thicknesses of .025 inches (.65mm) for die casting and .090 inches (2.3mm) for permanent mold casting are being produced. This thin-wall capability results in smaller, lighter, low cost components.
Zero Draft Angle Castability
Draft angle is the taper on the surface of a die required to facilitate removal of the cast part from the die cavity. In general, zinc alloys can be die cast with less draft angle than competitive materials. In fact, zinc components can sometimes be cast with zero draft angles. This is usually not possible with aluminum or magnesium alloys. Zero internal draft permits net shape manufacturing resulting in lower cost production.
The ZAMAK alloys, ZA-8 and ZA-12 have excellent dimensional stability characteristics. ZA-27, however, may require a stabilization heat treatment to minimize aging effects where exceptional tolerances are required.
Zinc alloys can be welded using MIG and TIG welding methods and brazed using special zinc filler rods. Welding is normally not an economical joining method for zinc die castings due to the high production volumes involved. Normally, mechanical devices are used for joining; however, flaring, riveting and crimping techniques are common low cost joining methods.
The low melting temperatures of zinc alloys are an energy-saving advantage for foundries; however, this also causes some loss of strength and hardness at moderately elevated temperatures. Plastic deformation or creep can occur with these alloys when they are stressed at less than their yield stress for extended periods at elevated temperatures. In general, applications that are above 250°F or under high constant stress should be avoided. Moderately stressed parts at ambient temperatures up to 150°F are best suited for ZAMAK and ZA alloys.