The unique thing about the die casting process is its ability to produce a wide range of parts with an extremely high degree of accuracy, quality, uniformity and surface finish.
The method is efficient to avoid the need for post-production machining and minimise fabrication time. Just imagine the amount of cost that can be saved by using these two methods.
The moulds used for die casting are made out of hardened steel which is good enough to handle various materials. The process of die casting is effective for materials with low melting points.
As per the 2018 reports, the market size for die casting has achieved an annual growth rate of 10.1%. The global aluminium dies casting size is about USD 24.91 billion.
The numbers indicate the increasing reliance on die casting for various metal alloys and their properties. The source of metals used for die casting will impact the overall finish and quality of the production.
In this article, we will discuss various alloys used in the die casting process. The die casting process’ result will be entirely dependent on the properties of metals such as melting point, conductivity, density, malleability, etc.
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Different types of die casting alloys
Die casting alloys are mainly chosen depending on the purpose at hand. The most popular choices are magnesium, aluminum and zinc.
Other options can also be used, such as lead, tin copper and brass.
However, these metals are less commonly used and are often treated as special materials for die casting.
Since different alloys have different properties, the manufacturer needs to understand specific requirements and choose the best for the project.
Different types of die casting alloys
Let us take a closer look at some of the different types of die casting alloys and their uses.
Zinc Alloys
One of the main reasons zinc alloys are used is that it is easier to cast and responds very well to the moulding process.
Zinc alloys are composed of multiple metals in specific ratios. Say, for example, a typical workpiece for zinc-based die casting consists of 7 to 10% tin, 4 to 7% copper, and 86% zinc.
The melting points of zinc alloys are in the range of 700 to 800 degree Fahrenheit.
A higher proportion of tin helps make the workpiece more flexible, while more concentration of copper helps to improve the rigidity.
Benefits and uses of zinc die casting alloys.
Zinc die castings are a suitable replacement for brass or cast iron but the tensile strength is much lower when compared to the other two metals.
The material cannot be corroded by the influence of seawater or alkaline substances. These are, therefore, used to coat the surface of metals to preserve the lustre.
Zinc based materials can withstand a force up to 17,000 pounds per square inch, but not beyond that.
As a result of this, the material cannot be used for any applications that involve enduring extreme amounts of force.
The mechanical property of zinc exceeds magnesium, bronze, aluminum, most cast irons and plastics.
Brass and Bronze Alloys
These materials are commonly used to create camshaft components, decorative products and washers.
Brass alloys consist of 40% zinc,60% copper and 2% aluminum. However, there are several variations, as well.
Benefits and uses of Brass and Bronze die casting alloys
Die casting brass and bronze alloys yield products with extremely accurate interior specifications and with a durable surface.
Brass and bronze materials can be effectively used for die casting, just like zinc-based alloys.
Holes can be drilled into the brass alloys only after casting but not during the casting process.
The brass alloys are highly suitable for applications that require a high tensile strength of up to 8000 pounds/square inch.
Brass and bronze alloys can be used for products with thickness 1/32 of an inch and weighing up to fifteen pounds.
Aluminum Alloys
Since these are generally lighter and stronger when compared to most zinc-based alloys, aluminum alloys are slightly difficult and expensive to create when it comes to die casting.
Aluminum die casting is extensively used in automobile gears and parts. Previously it was also used to create surgical instruments.
Benefits and uses of Aluminum Die Casting alloys.
The material has a high melting point of 1150 degree Fahrenheit and is most commonly composed of 92 percent aluminium mixed with 8 percent copper.
Adding magnesium helps boost the tensile strength from 21,000 pounds /square inch to approximately 32,000 pounds/square inch.
On the other hand, adding nickel helps to provide a better surface finish and improve rigidity.
Tin Alloys
Tin Alloys are used in applications that require corrosion resistance. These are the most commonly and widely used in the food industry.
The percentage of metals in the tin alloys can vary greatly depending on the purpose at hand.
Benefits and uses of Tin alloys
Tin alloys are highly valued for their resistance to acids, water and alkaline, making them an excellent choice for coating the inner walls of cans for storing beverages.
In general, tin alloys consist of 4 percent copper, 6 percent antimony and 90% tin. Die castings made out of tin alloys have a thickness of 1/32 of an inch and weigh under ten pounds.
The tensile strength is relatively low, below 8000 pounds/square inch.
What is the best type of metal for vehicle parts?
Moving vehicle parts will be under a lot of stress, and alloys should be handpicked to ensure that the components remain effective and efficient throughout the year.
Aluminum parts are excellent, but they will be expensive. Usually, aluminum-zinc alloys are preferred automotive die casting moving components such as gears, clutch wheels etc.
The high durability and corrosion resistance make it a popular choice for truck, car and other vehicle parts.
The excellent stiffness- weight ratio minimises the weight to the maximum possible extent and improves the mileage for heavyweight carriers.
The high thermal and electrical conductivity adds to its advantages, making it an excellent choice for computing, lighting, and electronics.
What is the best type of metal for making ammunition?
Since guns and ammunition have to smoothly operate at a high temperature, the metal chosen should be highly resistant to corrosion and temperature.
The most popular choice of metal while making guns are aluminum or zinc alloys. Aluminum is used in places where high strength is not required, like trigger guards.
What is the best type of metal for Surgical Equipment?
Medical equipment greatly varies in its functionality, and the type of alloys used will depend on the purpose of the equipment.
In general, you could see the usage of magnesium, zinc or aluminum to make the parts.
Magnesium is an excellent choice for diecasts with excellent corrosion resistance, low density, high strength to weight ratio, good electrical and thermal conductivity.
Magnesium alloys help to create parts that are incredibly lightweight and long-lasting.
The downside of die casting the magnesium alloy is that it requires specialised handling requirements that several die casting industries may be lacking, earning it the name “specialty” alloy.
You need to find the proper manufacturer to produce high volume parts as there are constraints in manufacturer and availability.
Zinc die casts help manufacture surgical equipment that is extremely lightweight, improving the precision during the surgery.
Zinc die casts are used for patient-facing devices. As zinc provides a suitable surface for painting or metal plating, it can be attractively painted or coated to have a glowing lustre.
As the metal has a low melting point, the mold life is better than aluminum die casting but cannot be used for high-temperature applications.
How to choose a suitable alloy for your needs?
There are no hard and fast rules when choosing a metal alloy. It depends on the requirements and applications. Make sure that the metal that predominates in your die cast part is suitable for your product.
If your priority is that the diecast should withstand high temperature, it is better to go for an aluminum-based alloy.
Do keep in mind that it requires a cold chamber die casting process for its manufacturing, while other alloys such as Magnesium or zinc work well with hot chamber die casting machines.
If your goal is to manufacture a lightweight part, it is better to choose Magnesium that is exceptionally light in weight. However, it is essential to understand that the metal is available only in limited supply.
Stainless steel and nickel alloys can be used if your main goal is to have corrosion resistance.
Brass alloys are the best for creating equipment and materials that have high thermal and electric conductivity.
Zinc alloys are the best for casting alloys with hardness, great strength and dimensional stability. Zinc allies give a natural glow after casting.
Bottom Line
While choosing a suitable metal for the precision die casting process, you will have to consider a variety of factors such as applications, the temperature at which it operates, availability of materials etc.
Thus an in-depth analysis of the requirement is necessary to zero in on the metal that works best for your required parts.
This article has discussed several metal alloys and their properties for the die casting process. The best way is to directly ask your die casting manufacturer about the choice of metals to handle your project. They might be able to help you to select the right option.
This article is a part of our comprehensive guide on “Die casting: Process, Equipment, Uses, and More”
