Aluminum Melting Point: Essential Facts and Tips for Metalworking Success

Aluminum is a vital material in industry, used for a wide range of applications, from airplane fuselages to cooking utensils. One of the reasons it’s so widely used is its adaptability to manufacturing, including casting.

In this article, we answer some key questions about aluminium, such as why it is so good for casting, and how to melt and control aluminum effectively.

Understanding Aluminum: Properties and Composition

Aluminum is a low density, silvery looking metal that has good strength, high malleability and excellent heat and electrical conductivity. Hundreds of different grades of aluminum are available, and range from easy to cast to extremely high strength.

In general, aluminum is quite malleable, with certain grades being perfect for complex drawn or formed parts. This is why aluminum is a common material to extrude, enabling a wide range of complex shapes.

Aluminum grades are collected into series, and each can differ significantly. For example 1000 series is nearly 99% pure Al, with very little additional alloying elements, and is praised for its high corrosion resistance, whereas the 6000 series is alloyed with small amounts of magnesium and silicone, and has a higher strength.

Aluminum Melting Point: What You Need to Know

Aluminum melts at around 660°C (1220.58°F) – this is one of the reasons aluminium is used extensively in extruding and casting, as it is relatively easy to melt.

It is important to note that the above figure is for pure aluminum, and alloying elements can affect this. Grades traditionally used for casting would have slightly lower melting points by design.

The Importance of Melting Point in Metalworking Applications

Many processes, such as casting, welding, brazing, or riveting, involve heating the material up significantly. In these instances, it’s crucial to understand the temperatures involved and the melting point of your chosen material.

In welding or brazing, for instance, tight control of the molten pool of metal is key for creating a strong, neat joint. If equipment was set up for welding steel or stainless steel for example, not adjusting this when moving to aluminum would not end well!

In a casting operation, aluminum is melted in a crucible before being poured into a mold. If the aluminum is overheated, various issues can occur. For one, any magnesium – a common alloying element – will oxidize at temperatures much higher than 700°C, causing solubility issues. Another issue is that hydrogen present in the atmosphere can become dissolved in the metal and cause various quality issues with the resulting cast components.

Tips for Efficient Aluminum Melting Techniques

Heating aluminium to its melting point takes a lot of energy, depending on the amount of material to be melted and the setup being used.

• Insulate the crucible: keeping the heat where you need it is key. Pointing a propane torch at a crucible will bring it to its melting point eventually, but if you can enclose the crucible in forge bricks or other similar material, less heat will be lost to the atmosphere, and more will be absorbed by the material.
• Start with small pieces: just like in cooking, the larger the piece to be heated, the longer it takes to get the internal temperature hot enough to melt. Cut up the material into smaller pieces, this increases their surface area to volume ratio and makes them melt much faster.
• Use Flux: various flux powders are available to reduce the impact of any impurities in the source material, which makes heating and pouring the aluminum much easier.

Common Mistakes to Avoid When Melting Aluminum

Even though aluminum melts more easily than many other metals, such as steel or stainless steel, it can still present some issues if not handled properly, as well as notable safety considerations.

• Overheating the material: as mentioned earlier, numerous issues can arise if aluminium is heated past its melting point, all of which will cause quality issues in the resulting product
• Not cleaning the metal first: To reduce the amount of impurity burning off in the crucible, and the amount of resulting porosity in the final product, the aluminum used should be as clean as possible
• Not preparing the work area: when casting aluminum, there are many dangers present, all resulting from the presence of a 600°C+ liquid that can spill or splash out of the crucible. It is important to prepare all your moulds, tools and equipment before heating any material.