Die casting is a common process that lets you cast components in plastic, resin, metal, or other materials. When everything is said and done, you'll appreciate the expanded finishing options and the stronger parts made with die casting. The most common metals for die casting are aluminum and zinc.
Aluminum is ideal for complex and thin-walled die-casting solutions. At the same time, zinc alloys are also renowned for die casting and offer top-notch features. This guide will examine zinc and aluminum die-casting based on benefits, uses, cost, and more to choose the best die-casting material among aluminum and zinc alloys.
Zinc alloys are stronger and heavier than most materials used in die casting because they have a high density similar to steel. Aluminum has a specific density of 2.7g/cm3, whereas pure zinc has a density of 5g/cm3. Due to its high density and greater impact resistance than aluminum, it is preferred for die castings.
Aluminum and zinc die-casting parts differ primarily in their mechanical characteristics. Below are the common properties of both die-cast materials and how they differ:
● Melting Point
Zinc is denser but has a lower melting point than copper. (4200C). The type of die-casting process you can use depends on the melting point. Zinc is more suitable for the hot chamber process because of its low melting points.
Zinc also prevents the mold from degrading, enhances production, lowers production costs, and determines the casting process selection. On the other hand, aluminum has a higher melting point. (6600C). As a result, it works well with the cold chamber process, which also lengthens cycle times while raising costs.
● Temperature Conductivity
Zinc alloy has better heat conductivity than aluminum die casting because it is more effective at absorbing and releasing heat. As a result, it is better suited for creating parts that generate a lot of heat or require heat to operate and be dissipated effectively.
● Corrosion Resistance
Zinc castings are preferable to aluminum in manufacturing die-cast components such as heat sinks or electronics. Castings made of zinc have superior corrosion resistance to die-cast parts made of aluminum. The former is, therefore, better suited for projects with challenging environmental conditions.
Die castings usually require different surface finishing techniques, unlike CNC machined parts. So aside from the process, the type of material also affects whether the part needs surface finishing. In contrast to castings made of aluminum, which can develop pores, pits, and blisters during the casting process, zinc castings do not have pores after casting, as you can see from their smoother/patterned surface. Aluminum casting consequently needs a compensating option for surface finishing.
However, both castings can have an excellent surface finish. Additionally, zinc works better with methods of surface finishing like plating, powder coating, painting, electroplating, and anodizing.
Both materials can be used in various industries. Zinc casting is more durable than casting in aluminum. They are the more popular die-casting choices for household appliances and automobiles. However, aluminum castings' strength-to-weight ratio makes them a superior material when you need lightweight and robust parts. This is an essential requirement for using aluminum castings in the aerospace sector.
The cycle time is significant when comparing zinc die casting to aluminum die casting. In contrast to aluminum die casting, zinc die casting occurs under high pressure and at a low melting point. Because of this, it has a short cycle time (the cycle rate of zinc casting is 150–200% higher than aluminum's).
Furthermore, zinc die casting heats up internally, unlike aluminum die casting, which uses the cold chamber process. In addition, zinc casting's effective heat dissipation causes the molten metal to solidify more quickly. The cycle time will shorten as a result.
Production costs vary depending on several variables, including material costs, production methods, operator expertise, cycle times, surface finishing, etc.
These are some of the characteristics that make Zinc die casting preferable over aluminum die casting:
Zinc die casting is appropriate for producing parts with thin walls due to their strength compared to other materials. You don't need to worry about the part's structural integrity since the material's density contributes to the part's stability when in use. Additionally, this will lower the cost of die-casting and the material requirement.
Bad environmental conditions, especially those that can cause corrosion, are suitable for zinc die-casting. When used in such circumstances, the casting's exceptional corrosion resistance ensures the formation of a protective layer on the parts.
Pressure is used in Less Residual Stress Die Casting to press the molten metal into the die. High-pressure and low-pressure die casting are the two pressure-based die casting processes; high-pressure die casting typically results in residual stress on parts. Low-pressure die casting is used to produce zinc dies. This consequently lowers the residual stress on the parts.
When using a delicate die-casting mold, choose zinc die-casting. This is because they can last approximately ten times longer than an aluminum die-casting mold. Furthermore, if you don't have enough money to pay for the tooling cost, go with zinc die casting.
Due to their low melting point, zinc alloys must be cast in a hot chamber using a high-pressure injection process. Unlike other materials, this will raise the cycle rate. In contrast to aluminum die casting, where the aluminum is melted outside the machine before being ladled into the injection machine, zinc is melted inside the die casting machine.
These are some of the characteristics that make aluminum die casting preferable over zinc die casting:
Die-cast aluminum components are renowned for being lightweight and high tensile strength. As a result, you should take them into account if you're looking for such properties. Due to their lightweight, aluminum die-cast parts are common in the aerospace sector.
Die castings made of aluminum are the best choice when working in environments with high temperatures, such as metallurgy. This is because of their high melting point, which guarantees that they maintain their structural and physical properties even when exposed to such high temperatures.
Because of their high electrical conductivity, aluminum die-casting is preferable for some electronic die-cast parts. For instance, shielding components from electromagnetic signals is essential for EMI shielding.
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Die castings made of aluminum and zinc are robust and long-lasting. Understanding the properties of the materials' inherent and die-casting-imposed properties is necessary to choose from any, though. This article compares zinc die-casting to aluminum die-casting to help you choose the best die-casting material for your project.
Die-cast parts made of zinc are more durable than those made of aluminum. Zinc die casting is said to be stronger than many popular non-ferrous alloys. Zinc alloys are 2.5 times stronger than aluminum die casting when compared to it.
Weight, resistance to corrosion, melting point, and thermal conductivity are all different between castings. Casting made of zinc is heavier and has higher corrosion resistance, a higher melting point, and better thermal conductivity.
Zinc casting is more corrosion-resistant than aluminum dies casting. However, pH is a factor in this. For instance, zinc and aluminum have the same corrosion resistance in alkaline solutions (pH 11).
