Magnesium Die Casting is carried out in a Cold Chamber Die Casting machine just like Aluminum. This is because Magnesium has a high melting point. So, it must be cast in a Cold Chamber Machine to avoid damaging the machine.
The process of Magnesium Die Casting is explained below step by step:
Magnesium alloys are melted under high temperature in a furnace separate from the machine
Molten Magnesium is carried from the furnace and poured inside the shot cylinder that connects with the die cavity
A hydraulic piston exerts high pressure to push the molten metal inside the die cavity
It is then left for solidification and cooling
The moving half is ejected to retrieve the casting
Excess metal from the casting is removed by trimming/machining
Additional surface finishing may or may not be provided depending upon the surface quality requirements for the parts. The casting process is similar to that of Aluminum Die Casting. The only difference is the Alloys used in both processes.
The most commonly used Magnesium Alloy for die casting is the AZ91D. It has pretty good mechanical properties with a good percentage of Aluminum mixed in it. They are other alloys of different composition but those are less frequently used for die casting.
MAGNESIUM DIE CASTING ADVANTAGES
Magnesium Die Casting has some benefits over other conventional die casting methods. Some of its major advantages are as follows,
Magnesium Alloys are the lightest metal used in the die casting industry. It has a specific gravity of only 1.738. It is about 75% lighter than Iron and 35% lighter than Aluminum. So, That makes it an ideal choice for products that needs lighter parts.
Magnesium alloys are considered the easiest metal to machine. So, handling Magnesium Die Castings is more convenient. Finished parts can be machined faster involving less machining cost in production.
Good Strength-to-Weight Ratio
Magnesium Die Casting are not only lighter but also strong and durable. It has excellent Strength-to-Weight ratio. So it is preferred for automobile and aerospace parts where light yet reasonably strong parts are compulsory.
Dimensional Stability with Thin Wall support
Magnesium parts have good dimensional accuracy and are quite stable. Walls can be made thinner which helps reduce the castings weighs even more.
Good Thermal and Electrical Properties
Magnesium Die Casting has high electrical conductivity properties. It also exhibits EMI and RFI shielding properties that make it an excellent choice for electrical housings. It can also retain its strength in higher operating temperatures.
As we can see, Magnesium Die Casting has a good number of benefits that should make it a good choice for many applications. But there are some drawbacks involved that would make it less favorable options compared to others.
APPLICATIONS OF MAGNESIUM DIE CASTING
Even though Magnesium Die Casting is not as popular as Aluminum Die Casting it has noticeable applications in the following industries,
The fact that Magnesium Die Casting offers a significant reduction in weight without compromising the strength is a big plus. The Aerospace and Automobile industry, in particular, is the ones with the most application of Magnesium.
It is gaining popularity in portable consumer electronics and sports equipment as well. Although it is rather a less practiced die casting method and the cost of production is much higher. When compared to Aluminum, the reduction in weight may not justify the extra cost.
MAGNESIUM DIE CASTING BETTER THAN ALUMINUM DIE CASTING?
Magnesium and Aluminum Die Casting share a lot of things in common. Both of the processes mainly uses Cold Chamber Die casting machine. They are both lightweight and strong non-ferrous metals.
But when it comes comparing Magnesium Die Casting vs Aluminum Die Casting, Aluminum has the upper edge. The reasons why Aluminum die casting remains as a more preferable choice is pointed out below.
Magnesium is lighter than Aluminum. But it is not so stable and tends to bend under heavy stress. Aluminum has better mechanical properties than Magnesium and it is much more stable.
A major concern is its cost. Manufacturers want the best performance while spending the least. Magnesium Die Casting doesn’t seem to agree with that. It is more expensive than Aluminum Die Casting and not a budget-friendly option.
Magnesium is highly reactive. So, it is a bad choice for parts that will be exposed to rough environments. You will need additional coatings to protect your parts that will further increase the production cost.
So, there are limited applications of Magnesium Die Casting where its lightweight is valued more over its disadvantage of being soft and costly. Some Magnesium alloys do seem to overcome a few of the issues.
The drawbacks are ultimately minimized by alloying Magnesium with a high percentage of Aluminum in it. The Aerospace and Automotive industry is using Magnesium castings for better fuel economy but with an obvious rise in the production cost.
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