Aluminum Extrusion

What is Aluminum Extrusion?

Aluminum Extrusion is a metal-forming process used to create objects of a fixed cross-sectional profile by pushing material through a die of the desired cross-section. Extrusion works similarly to a Play-Doh press in which the malleable material is forced through the press and through the die opening fitted with a particular shape.

Like PlayDoh, for a hollow shape the metal flows through the opening between the part of the die that forms the outside diameter and an inside mandrel supported horizontally. The metal separates into tube halves and "welds" back together due to the pressure needed to make it flow through the opening into a tube shape.

Extrusion may be continuous, theoretically producing indefinitely long material — or semi-continuous, producing many pieces. Though Aluminum is the most commonly extruded material, the process can be used for a variety of metals, polymers, ceramics, and concrete. Extrusion offers excellent surface finish and part strength.

How Does Aluminum Extrusion Work?

Once the desired profile shape has been developed and the appropriate alloy selected, an extrusion die and associated tooling are produced. The material billet — a cast log of extrusion feedstock — and tooling are preheated. During extrusion, the billet is still solid, but has been softened in a furnace.

The actual extrusion process begins when the press ram applies pressure to the billet within a container. Hydraulic presses exert between 100-15,000 tons of pressure. The pressure capacity of a specific press determines how large an extrusion it can produce.

As pressure is applied, the billet is first crushed against the die, becoming shorter and wider until its expansion is restricted by the container walls. As the pressure increases, the soft (but still solid) metal has no place else to go besides squeezing through the shaped die to emerge on the other side as a fully formed profile.

The formed profile is cut off at the die, and the remainder of the metal is removed to be recycled. After it leaves the die, the still-hot extrusion may be quenched, mechanically treated, and aged to impart desired metallurgical properties and physical performance.

After sufficient aging, whether in an aging oven or at room temperature, the profiles are moved to other areas of the plant for secondary operations such as: