Die-casting is a metal casting process. It is a process where it places molten metal under high pressure to form it to a mold cavity. The mold cavity is formed from two steel machined parts.
The materials used in the die-casting process are non-ferrous metals, namely zinc, copper, aluminum, lead, pewter, and tin-based alloys. The type of metal used depends significantly on whether a hot chamber or a cold chamber is used in the die-casting process. Let’s take a look further into the metals used in the die-casting process as well as their advantages and disadvantages.
Aluminum Alloys (Al)
Aluminum alloys have a specific gravity of approximately 2.7g/cc. With that being said, aluminum alloys are amongst the most lightweight structural metals available. They are also widely used because they are known to be often the most economical die-casting metal. In fact, the majority of the castings done worldwide are aluminum alloys.
When aluminum alloys are used, they also involve other elements: silicon, copper, magnesium, iron, manganese, and zinc. Each element has an effect on the metal independently and interactively,
Among all the aluminum alloys, the Alloy A380 is the most commonly used alloy. It is widely used because this alloy has the best combination of material properties. This alloy can be seen in appliances, lawn mower housing, automotive components, power tools, engine brackets, and so on.
This alloy serves as an alternative to Alloy A380. This is used when the user needs more intricate components that need improved filling characteristics or more durability.
Lastly, this alloy is used when someone needs an alloy for better corrosion resistance, higher strength, at higher temperatures, and better ductility. However, the downside to using this alloy is that it is harder to cast and the production yields decrease.
Magnesium Alloys (Mg)
Magnesium alloys are also used in the die casting process. They have a specific gravity of 1.74g/cc. It is considered the lightest commonly used structural metal. Among the magnesium alloys, the AZ91D is the most used.
The magnesium alloy has the highest strength commercial. It has excellent castability and corrosion resistance as well. Powerful corrosion resistance is achieved by imposing strict limits on the allowable impurities of iron, copper, and nickel. You will be able to see these magnesium alloys being used in sports equipment, steering columns, sewing machines, vacuum cleaners, and others.
The Die-Casting Process
The Die-Casting ProcessWhen magnesium alloys are used in the die-casting process, one has to be extremely careful. Magnesium alloys can be dangerous if they catch fire during the die-casting process. In fact, the fire can even reach 3,100 degrees Celsius.
Water will be of no help, it will only accelerate the fire. Magnesium alloys can receive decorative chromate treatment, painting plating, and phosphate coatings for surface treatments. When used in computer parts, magnesium alloys are treated chemically s to protect against tarnishing.
Zinc Alloys (ZN)
Among the alloys, zinc alloys have the broadest physical and mechanical properties. That is why they also have great castability and finishing characteristics.
- Allows greater variation in design.
- Maintains dimensional tolerances better.
- Has a higher impact strength than other alloys, except for brass
- The die life is longer and maintenance is minimized (this is because they are cast in lower temperatures.
Zinc alloys include Zamak, which is an acronym for Zinc, Aluminum, Magnesium, and Cooper. The most common ones are Zamak series no. 2, 3, 5, and 7.
Zamak contains 4% aluminum and small amounts of magnesium. This shall improve the hardness and strength and to protect castings from corrosion. Zamak always uses the hot chamber process. This allows for maximum casting speed.
Here at SEI Castings, we produce custom and standard, high quality, precision aluminum die-cast products. We specialize in prototyping and short-run casting orders. Let’s talk about how we can help with the parts that you need. Reach out to us today!