Die casting is a manufacturing technique suitable for the production of parts with complex designs that requires accuracy and large-scale production. The technique is compatible with metals, with popular ones being zinc, magnesium, and aluminum. Of these different materials, zinc die casting vs aluminum die casting is the most common comparison in metal fabrication.
Both materials have unique inherent properties and applications. However, the process further improves these properties. As a result, you need to understand die casting and its effects on the materials. This article compares aluminum die casting and zinc die casting so you can understand them and how to use the correct one.
Aluminum die casting and zinc die casting exhibit unique properties which determine their applications. Below are the common parameters that can allow you to differentiate both materials and choose the right one:
Zinc alloys have a high density similar to steel, which portrays them as stronger and heavier than most die casting materials. Pure zinc has a specific density of 5g/cm3 compared to aluminum’s 2.7g/cm3. As a result, of its high density, it has a high impact resistance than aluminum parts and is the choice of material for making castings for structural applications.’
The major distinction between zinc die casting and aluminum parts are based on their mechanical properties. Below are the common properties of both die-cast materials and how they differ:
Although denser, zinc has a lower melting point (4200C). The melting point is an important parameter in die casting as it determines the type of die casting process you can use. Zinc's low melting point makes it more compatible with the hot chamber process.
Aside from that, it also does not lead to the degradation of the mold, improves production, reduces lower production costs, and determines the choice of the casting process. On the other hand, aluminum has a higher melting point (6600C). Hence, it is compatible with the cold chamber process, which, aside from increasing the cost, increases the cycle time.
Zinc alloy has better heat conductivity than aluminum die casting as it can efficiently absorb and dissipate heat. As a result, it is more suitable for producing parts that generate high heat or work with heat and need to dissipate such heat efficiently.
Zinc castings are better than aluminum in making die cast components such as heat sinks or in electronics.
Zinc castings have better excellent corrosion resistance than aluminum die-casted parts. Therefore, the former is more suitable for projects in harsh environmental conditions.
Molds used in zinc die casting do not need to be overly strong due to the material’s less abrasive nature and low melting point. Due to these properties (i.e., less abrasiveness and low melting point), there is a reduction in mold damage and tooling cost. Thus, molds used in making zinc castings can last over 1,000,000 shots compared to aluminum’s 100,000 shots.
Unlike CNC machined parts, die castings often need secondary surface finishing options. Aside from the process, the type of material also determines whether the part need surface finishing.,
Zinc castings do not have pores after casting, evident in their smoother/patterned surface, and this is unlike aluminum, which can form pores, pits, and blisters during casting. As a result, aluminum casting requires a compensating surface finishing option.
Nevertheless, both castings are subjectable to surface finishing. Also, zinc is more compatible with surface finishing options such as plating, powder coating, painting, electroplating and anodizing.
Both materials are applicable in several industries. Zinc casting is stronger than aluminum casting. They are the more common home appliance and automotive die casting options. On the other hand, aluminium castings’ strength-to-weight ratio renders it a better material when there is a need for lightweight and strong parts. This is an important criterion for the use of aluminum castings in the aerospace industry.
Another major parameter to consider in the aluminum die casting vs zinc die casting comparison is the cycle time. Zinc die casting occurs at high pressure, and low melting point, unlike aluminum die casting. For this reason, it has a low cycle time (zinc casting has a cycle rate that is 150-200% higher than aluminum).
Furthermore, the heating of zinc die casting occurs internally, unlike aluminum die casting, which uses the cold chamber process. Aside from that, zinc casting’s efficient heat dissipation means that molten metal will solidify faster. As a result, the cycle time will reduce.