Material properties that help solve today's engineering
problems.
Strength
A alloys deliver the highest tensile strength among the most
widely used non-ferrous alloys and match or exceed that of most cast irons.
Yield strength is a major ZA alloy attribute reaching 55,000
psi for ZA-27, that's more than twice that of A380 die cast aluminum, and
significantly higher than the strongest plastics. Even ZAMAK 3, the most common
alloy has a significant yield strength advantage over A380 aluminum, showing 3
times greater elongation, while maintaining greater hardness and higher
stiffness.
Rigidity
Zinc alloys are rigid engineering materials. Their elastic
moduli are greater than those of aluminum and magnesium alloys, and are an
order of magnitude greater than those of plastic. This, combined with their
high strength allows the volume of individual castings to be markedly reduced,
saving space and weight.
Toughness and Ductility
High impact strength and good ductility are qualities of zinc
alloys that are rarely found in most other casting alloys. Ductility is
important for bending and crimpling in post-casting assembly operations, while
impact strength provides performance in rough environments. Fracture toughness
is also greater than for most aluminum alloys and cast irons.
Hardness
ZAMAK alloys provide high hardness and abrasion and wear
resistance. Optimum hardness is provided by the ZA family whose Brinell
Hardness ranges from 95 to 122 when die cast. These values are much higher than
the 70 to 85 BHN displayed by aluminum alloys, and much higher than the
hardness values of engineered plastics. Along with high hardness, ZA alloys
also exhibit excellent abrasion and wear resistance.
Conductivity
As zinc alloys conduct both heat and electricity, they can be
used for heat dissipating devices such as heat sinks. Zinc's excellent casting
fluidity permits thinner fin and cooling pin design to better dissipate heat.
Zinc's excellent electrical conductivity also provides good EMI, RFI and ESD
shielding.
Non-sparking and Non-magnetic
Aluminum alloys can generate a spark when struck with a rusty
iron component. All zinc alloys, except ZA-27, are classified as "non-sparking"
and are the perfect low-cost alternative to bronze in potentially explosive
environments.
Zinc's non-magnetic properties are ideal for use in
electronics and other applications where delicate moving parts are subject to
magnetic disturbances.
Fatigue Strength
This measure of a material's ability to withstand cyclic
loading is and important design criterion. Both the ZAMAK and ZA alloys have
high fatigue strengths.
Design (Creep) Stress
The allowable design stress, or resistance to creep at room
temperature, of ZA alloys is far better than for all but the most esoteric
engineering plastics. The room temperature design stress of die cast ZA-27, for
example, is 10,000 psi (stress required for the creep of 1% in 100,000 hours).
This property allows ZA alloys to be used in applications subject to
significant static loading. However, permissible design stress drops with
increasing temperature, and a careful review of all constant load applications
at temperature is required to determine the suitability of zinc alloys.
Pressure Tightness
Soundness of castings is largely related to product design,
tooling layout and process control. Die cast ZAMAK alloys, ZA-8 and ZA-12 are
often used for pressure tight applications. For sand and permanent mold
casting, ZA-12 is the preferred material. All zinc alloys solidify into a dense
strong matrix with excellent pressure tightness.
Damping Capacity
All of the ZAMAK and ZA
alloys have excellent damping capacity. At 20ºC,
ZA-27, the highest damping zinc alloy, has nearly ten times greater damping
capacity than A380 aluminum or mild steel. At 100ºC
damping capacity increases and all of the zinc alloys become "HIDAMETS" (high
damping metals) and have damping capacity greater than that of grey cast iron.
This property makes zinc alloys the perfect choice for housings where vibration
absorption is required.
Corrosion
Resistance
Zinc
has excellent corrosion resistance under normal atmospheric conditions, and in
many aqueous, industrial and petroleum environments. Corrosion resistance can
be enhanced by such treatments as plating, chromating, painting and zinc
anodizing.