Engineering
characteristics that answer your most critical needs.
Accuracy
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.
Machinability
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.
Dimensional
Stability
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.
Joining
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.
Temperature
Limitations
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.