Die Casting is normally done with non-ferrous metals only. It is not impossible to cast ferrous metals. But that is much more complex and not commonly practiced. Some of the common metals used as Die Casting Alloys are Aluminum, Zinc, Magnesium, Copper, Lead, Tin, etc. There are many options available for die casting alloys. But, Aluminum and Zinc are most commonly used for die casting. Magnesium also has a good number of applications. Other Die Casting Alloys are less commonly used.
Aluminum is the most commonly used die casting alloy all over the world. It is one of the cheapest metals out there. There are many varieties of Aluminum die casting alloy available in the market such as A360, A380, A383, A384, A390, etc.
A380 Aluminum Alloy
This is the most commonly used Aluminum Alloy used for die casting with a balance of performance and strength. It is very lightweight and has an excellent strength-to-weight ratio. The electrical and thermal conductivity is very good and it can retain strength at high temperatures.
A360 Aluminum Alloy
This one is the toughest of them all and has the best corrosion resistance, but it is more difficult to handle and often ends increasing the production cost a bit.
A383 Aluminum Alloy
The properties are quite similar to A380 but with slightly better fluidity. Although that comes with a reduction in durability.
ZINC DIE CASTING ALLOYS
Zinc alloys are known for their castability. They have exceptional fluidity and mechanical strength. They can produce castings with very intricate details. But the downside is that it is multiple times heavier than Aluminum.
So, they are not the best choice for things that calls for lighter parts such as vehicles, automobiles, and portable electronic devices. ZA and Zamak are the most commonly used Zinc alloys.
Zinc-Aluminum (ZA) Alloy
ZA alloy uses Zinc as the base metal and Aluminum as the major alloying ingredient. Other metals are also present but the percentage of Aluminum is much higher in it. ZA alloy is subdivided into multiple categories such as ZA8, ZA12, and ZA27 with the number representing the percentage of the Aluminum present.
A8 alloys are cast using Hot Chamber machines, while the other two require a Cold Chamber machine. The higher percentage of Aluminum causes an increase in the melting temperature and a decrease in castability.
Zamak Alloys have Zinc as base metal and have Aluminum, Magnesium, and Copper, as an alloying ingredient. Zamak alloys are categorized as Zamak 2, 3, 4, 5, 7. All Zamak alloys have a constant composition of 4% Aluminum.
Each of the Zamak alloys has slightly different properties and suitable for different fields of application.
MAGNESIUM DIE CASTING ALLOYS
Magnesium is the lightest structural metal and considered the easiest metal to machine. But not the cheapest solution though. They are lighter than Aluminum but don’t share the same durability. They are highly reactive and have bad corrosion resistance. So, they are alloyed with other metals for better performance.
This is the most commonly used Magnesium Die Casting Alloy. It has 9% Aluminum and 1% Zinc. It retains Magnesium’s lightweight properties but has better corrosion resistance due to a higher percentage of Aluminum.
FACTORS TO CONSIDER WHEN CHOOSING DIE CASTING ALLOYS
There are many material choices available for die casting. But you should keep some factors in mind when choosing one. Below are some of the parameters to consider when deciding on Die Casting Alloy.
The cost of raw material is a major portion of your overall production cost. Manufacturers will always look for the cheapest solution available which will get the job done. But keep in mind the castability too, because materials that are difficult to handle will eventually cost more.
The mechanical strength requirement of a Die Casting Alloy is based on the field of application. No matter which Die Casting Alloy you choose, it must have the minimum mechanical strength you need to avoid failure during service condition.
Thermal Conductivity is very important where your parts might be subjected to high temperatures. Because some metals fail under higher temperatures. So, you will need something that will retain its strength in such a condition.
This is especially important for parts to be used for electronics. Sometimes you will need parts made of alloys that offer high Electrical Conductivity. Often times you will need something with better insulation against electricity.
Die Casting Alloys with good corrosion and wear resistance is highly desirable. That will reduce the need for regular maintenance of your parts. You can also use such parts without any special coating which can save some production cost.
WHICH DIE CASTING ALLOYS IS THE BEST?
When it boils down to the best, Aluminum Alloy is the answer. Aluminum Alloys have all the ideal properties that should be present in a Die Casting Alloy. Aluminum Alloys are the cheapest and most alloys available in the market.
Aluminum Alloy is several times lighter than Iron but has strength close to it. So, it is a great alternative for Iron. So, the Automobiles and Aerospace industries are shifting towards Aluminum Die Casting for lighter and durable parts.
And unlike Iron, Aluminum has excellent Corrosion protection that will often make it more preferable of an option. Magnesium offers great machinability but Aluminum is still quite machinable itself. Aluminum can also retain its strength at very high temperatures. It also has exceptional heat dissipation that makes it an ideal choice for use in electronics. So, considering all these facts Aluminum Alloy offers the best productivity compared to the cost.
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