Introduction

Various industries make use of die-cast products. Examples are the electrical, automotive, medical industries, etc.

In die casting, there are different metals you can use. So, you probably want to know these metals and which particular metals are suitable for you. Right?

Calm your nerves! That is exactly what we will show you here. Follow closely.

What metals can you die cast?

You can die cast both non-ferrous and ferrous metals. The non-ferrous metals you can die cast include zinc, magnesium, aluminium, brass, copper, lead, nickel, brass, titanium, etc.

The ferrous metals you can die cast are cast iron, grey iron, carbon steel, malleable iron, gray iron, cast iron, wrought iron, etc.

However, non-ferrous metals are more commonly die cast than ferrous metals. You know why? It is because non-ferrous metals are not susceptible to rust and corrosion like ferrous metals.

So, let’s take a quick look at the main differences between both types of metals.

The main difference between non-ferrous and ferrous metals

Non-ferrous metals do not contain large quantities of iron. This makes them less prone to rust and corrosion. These metals do not show the red flaky metals that steel and other ferrous metals show.

Conversely, ferrous metals contain a high carbon rate. This makes them susceptible to rust and corrosion. If iron is the first or second most dominant element in a metal, then such metal is a ferrous metal.

Non-ferrous metals

Generally, pure metals are non-ferrous elements, except iron. Non-ferrous metals are ordinarily gotten from minerals such as silicates, sulphides and carbonates. Thereafter, they are refined through electrolysis.

Non-ferrous metals have no iron contents, which makes them corrosion-resistant. They have several amazing qualities. They are lightweight, corrosion-resistant, impact-resistant, low density, good thermal, electrical conductivity, non-magnetic, easy to fabricate, etc. They also have strong performance under temperature.

Because they are non-magnetic, they are suitable for making die-cast parts for electronics/electrical applications.

Also, some non-ferrous metals have distinctive features too. Some can withstand high temperatures, some are soft and ductile, while some are hard and brittle.

Common non-ferrous metals for die cast include zinc, aluminium, brass, copper, lead, nickel, brass, silver, etc.

Uncommon non-ferrous metals include mercury, cobalt, cerium, bismuth, cadmium, gallium, germanium, selenium, tellurium, vanadium, lithium, etc.

Now, let’s consider some of the common non-ferrous metals used in die casting.

• Zinc

You can get this metal from zinc ores such as calamine and zinc blende. It is covered by dull basic zinc carbonate in moist air. It is a fairly reactive metal that combines with oxygen and other metals. It has a bluish-white colour and a density of 7.14g/ml.

When you heat it to a temperature of 100° to 150°, it becomes malleable and ductile. It has a melting point of 4/9 centigrade. It also has a tensile strength of 700-1400kg/cm².

Zinc is the 23rd most abundant element in the earth’s crust. It has high dimensional accuracy and stability. It also has a good thin wall capability. Zinc has super casting fluidity, strength and stiffness.

Because of its structural intensity, you can use it to die cast complex cast parts for the electronic and automotive industries.

Also, it is less abrasive and has a lower melting temperature. It has a tighter tolerance and produce die-cast parts with great impact resistance. Some common zinc alloys used in die casting are ZA-8, ZA-27, ZA-12, among others.

• Aluminium

Aluminium is one of the most common metals used for die casting. You can use it to create die-cast parts of any geometry, lustre or surface texture.

It is lightweight and has high operating temperature tolerances. It has outstanding strength and good corrosion resistance. It is resistant to weather, common atmospheric gases and wide range of liquids.

Also, it has good EMI shielding properties and high elasticity. This metal has a high reflectivity too.

Aluminium die-cast parts are used across various industries. These include the automotive, aerospace, construction, electronics, energy, industrial, telecommunications, electrical industries, etc.

There are different aluminium alloys you can use for die casting. The common alloys are A380, 383, B390, A413, A360 and CC401:

A380: This is one of the commonest alloys used in aluminium die casting. It is lightweight and has excellent physical and mechanical properties. It is strong at high temperatures. It also has excellent fluidity and pressure tightness. It is resistant to hot cracking.

 A383: This alloy is mostly used to make intricate components requiring very specific die-filling characteristics. It also has higher strength at high temperatures.

A360: This alloy has higher strength at high temperatures, higher corrosion resistance, better ductility, etc. However, it is hard to cast. So, many die casts manufacturers do not use it often.

A413: This contains an appropriate balance of physical and mechanical properties. It does not crack. It also has good pressure tightness. It is suitable for die casting.

• Magnesium

Magnesium has a silver-white colour that can ignite easily. It is lightweight and is one-third less dense than aluminium. It is produced from water, brines and magnesium-bearing minerals.

Magnesium is 38% lighter than aluminium and 75% lighter than steel. It is fully recyclable too. It is the eighth most abundant element and is suitable for casting thin-walled and complex parts. It provides excellent EMI-RFI shielding. It has high impact resistance.

Also, it has a 2/3 rate of aluminium density. Because of its lightweight, you can use it to produce automobiles and aerospace die-cast parts, among others.

Magnesium die can meet tight tolerances. It melts at a lower temperature and is easily machinable. It is highly reactive and can retain strength at high temperatures. It has an excellent strength-to-weight ratio. It also has great energy absorbing capabilities.

The different magnesium alloys you can use in die casting include:

AM50: It has a lower aluminium content than AM60. Also, it has a high ductility at a slightly reduced strength. Consider using it when the performance required demands elongation properties beyond AM60.

AM60B: This magnesium has good energy absorbing properties, excellent ductility, strength and castability. It is mostly used for die casting automotive components.

AZ91D: It is the commonest magnesium alloy for die casting. It is mostly used for producing mechanical components that require toughness.

It usually contains 9% aluminium and 1% zinc 

• Brass

Brass is largely made up of copper and zinc. It contains 33% zinc and 67% copper. Also, it contains little proportions of some elements like phosphorus, arsenic, lead, manganese, aluminium, silicon, etc.

It has excellent heat and electrical conductivity. Although silver is more conductive than brass, brass is preferable for conduction applications. This is because of its excellent thermal resistance.

It has a density of around 0.303lb/cubic inch. It has a dimensional accuracy of 0.1mm, and a wall thickness of 0.75mm. Also, it is a ferromagnetic substance as it has no magnetic properties.

Brass die casting produces complex shapes at lower pressure. It has extreme abrasion-and-wear resistance for cast-in-steel components.

Note that some types of brass can hold more corrosive substances like saltwater. Because of its less friction, brass is suitable for manufacturing die-cast parts for the furniture industry.

Ferrous metals

Ferrous metals mainly contain iron. So, they are susceptible to corrosion when exposed to moisture.

To determine whether a metal is a ferrous metal, you should measure the valance. If the valance is -12, then the metal is ferrous.

In addition to iron, they are always mixed with some other alloying elements such as manganese, chromium, nickel, vanadium, etc. So, different ferrous metals can have diverse features, depending on the alloying elements used in mixing them.

For example, low-carbon steel (a ferrous metal) is soft and ductile because it has little carbon. On the other hand, cast iron (another ferrous metal) is soft and brittle.

Ferrous metals have high magnetic properties. Also, they have high tensile strength, durability, hardness, and good electrical conductivity. They are magnetic, recyclable and durable.

Now, let us consider some common ferrous metals used in die casting.

• Carbon steel

Carbon steel contain other alloying elements in low quantities. These elements include sulphur, silicon, manganese, phosphorus, etc. These elements are in low quantities such that they don’t alter the inherent properties of carbon steel.

There are three different categories of carbon steel, which are:

The high carbon steel: They contain 0.6-1.0% carbon. This gives them a high strength. They are the strongest of the non-alloyed steels. They are suitable for applications that require resistance to mechanical wear.

The medium carbon steel: They contain 0.25-0.6% carbon. They are stronger than the low carbon steel but not strong as the high carbon steel. Because of their higher level of carbon and manganese, they  can be tempered and quenched. Note that they have reduced ductility than the low carbon steels.

The low carbon steel: They contain 0.05-0.25% carbon. They are very soft and have lower tensile strength than other steels. It is not suitable for heat treatment. You can measure the surface hardness by carburising.

• Malleable iron

To produce malleable iron, cast the ‘white iron’ and then apply a special annealing heat treatment. This will cause the metal to lose its brittleness and change the internal microstructure.

They have a similar composition to white iron, except that it contains more carbon and silicon. Also, they have graphite nodules that are not spherical like they are in ductile iron.

They have great ductility and excellent surface hardening. Die casting made with malleable iron can easily bend, straighten and can sustain machining.

• Grey iron

Grey iron contains 95% iron and 1-3% silicon. They have low solidification, excellent castability, machining, dampening capacity, etc. They also have graphite microstructure.

They have good galling and wear resistance. This is because the graphite flakes lubricate themselves. They also have less solidification shrinkage than other cast iron.

Because they have low tensile strength and ductility, they almost do not have any impact and shock resistance.

• Cast iron

They have at least 2% carbon. They also contain a varying quantity of manganese, silicon, phosphorus, and sulfur.

They have excellent machinability and vibration damping. However, they have low tensile strength. So, they are not suitable for producing castings with high physical requirement

Which should you choose between non-ferrous and ferrous metals

The suitable metal for your die casting depends on several factors:

• If your project requires strong die cast parts with durability and strength, consider ferrous metals.

• If you want lightweight die-cast parts such as for aerospace projects, consider using non-ferrous metals. Ferrous metals are heavier than non-ferrous metals.

• If you are on a tight budget, consider using ferrous scrap metals. Ferrous metals are less expensive than non-ferrous metals.

• If you want  highly malleable material, consider using non-ferrous metals So, to choose a suitable metal, you need to consider your peculiar needs.

Conclusion

In this article, we have taken you through the various metals you can die cast and their features. This knowledge will help you when deciding which metals to use for die casting.