Metal extrusion: what it is and how hot extrusion works

What is the extrusion process?

The metal extrusion process is an industrial production technique that consists of the plastic deformation of a material, typically a metal such as aluminium, pushed through a mold called a matrix to obtain a desired shape. This type of process is widely used to create parts and components with complex and detailed shapes for various sectors, from construction to aeronautics.

Fundamentals of Metal Extrusion: how does it work?

Metal extrusion is a manufacturing process that involves heating a material, usually an aluminium, copper, or steel alloy, until it becomes malleable and consequently mouldable according to one’s needs. The heated metal is then pushed through a die, to obtain a specific shape. To obtain a quality extruded product with optimal characteristics, not only is extreme precision required throughout the entire process, but also effective temperature control and exact calibration of the extrusion forces.

Phases of the Metal Extrusion Process

To better understand metal extrusion we need to identify the main processing phases that generally characterize this particular process.

Preparation of the Material

The first phase consists in the preparation of the raw material: the metal is cut into bars or billets which are subsequently heated at variable temperatures based on the alloy used. Aluminium extrusion, for example, takes place at extrusion temperatures around 500-550°C for the most common alloys. While, as regards steel extrusion, we work at extrusion temperatures between 1,100°C and 1,300°C, the variation depends on the specific steel alloy used.

Direct extrusion

Once the ideal temperature has been reached, the material is ready to be subjected to direct extrusion which refers to the practice of extruding a metal without intermediate steps or without significant additional processing. The heated metal is then loaded into the extrusion chamber of the press, where considerable pressure is exerted via a ram or hydraulic piston, to push it through the die. This phase is fundamental to guarantee the high quality of the finished product and, for this reason, rigorous control and maximum precision is required.

Indirect extrusion

Alternatively, indirect extrusion is a metalworking process that involves using a die to form the material into a desired shape. This process differs from direct extrusion, where material is pushed directly through a slot or die to create the desired shape. In indirect extrusion, the material is pushed through an extrusion chamber, which can be heated to facilitate plastic deformation of the material. This method is often used for the production of complex or large parts, allowing greater flexibility in the design and production of metal components.

Cooling and Finishing

After being extruded through the die, the metal is cooled so as to retain the impressed shape. Cooling can occur in various ways: naturally or through cooling systems that use water or air. Finally, the extruded aluminum or steel can be cut to the desired length and subjected to finishing touches such as grinding, polishing or specific surface treatments.

Advantages and Applications of Metal Extrusion

The metal extrusion process offers several advantages, including the ability to produce parts with high mechanical strength and dimensional accuracy. It also reduces material waste, as most of the raw material is used to form the final part. This technique is also very versatile: in fact, it finds countless applications, contributing to the production of components for cars, airplanes, lighting systems, heating systems, household appliances and much more.

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Aluminium extrusion: why it is one of the most used metals

Aluminium is at the centre of metal extrusion thanks to its intrinsic qualities (lightness, resistance, durability, and ease of processing) and the variety of composition of its alloys. In fact, by modifying the type of aluminium alloy it is possible to have different and specific mechanical properties and this makes extruded aluminium perfect for the most varied applications.

Aluminium alloys and their uses

The 1000 series alloys, characterized by very high purity, generally over 99% aluminium content, are known for their excellent corrosion resistance and their good electrical and thermal conductivity. These properties make them ideal for applications in the electronics sector or for use in industrial plants.

However, 6000 series alloys, such as 6061 and 6063 aluminium, are widely used in structural applications due to their combination of strength and workability. They are used in automotive chassis, transportation systems, the aerospace industry and in architectural structures.

Aluminium Extrusion Process

In the aluminium extrusion process, the processing temperature is crucial and varies depending on the alloy and shape of the part. Precise control of temperature, extrusion speed and pressure are essential to avoid defects and achieve the desired quality of extruded aluminium.

Applications of Extruded Aluminium

The applications of extruded aluminium range across a wide variety of sectors. In the automotive field, lightweight and extremely strong extruded aluminium frames are key to reducing vehicle weight and improving fuel efficiency. In the aerospace industry, extruded aluminium is used to create lightweight but still strong components for aircraft and rockets. Furthermore, extruded aluminium also finds space in sectors such as electronics thanks to its excellent thermal conductivity and, due to its lightness and resistance, it is an excellent choice for creating frames for both solar panels and bicycles.

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Protecting metals during extrusion: ATP takes care of it

ATP offers a series of borosilicate glass lubricants to protect steel and titanium while offering boron nitride products to protect aluminum in the direct extrusion process. ATP products form a protective barrier between the extrusion die and the metal, preventing the latter from remaining attached to the die, damaging it.

If you need information on our extrusion glass, do not hesitate to contact us! We are always available to recommend the product best suited to your needs.