Aluminum extrusions are shaped pieces of aluminum produced by heating aluminum blocks and pushing them through a die shape to create specific patterns. Extrusions can be manufactured in many sizes and in almost any shape for which a die can be created. Extruded aluminum offers durability and structural strength, and it is fully recyclable.
Aluminum extrusions begin with solid, cylindrical forms of aluminum called billets. Sometimes aluminum is used in its pure form, but it is often blended with magnesium, copper, manganese or silicon to create alloys with particular properties. Depending on the blend, alloys can offer increased corrosion resistance, increased strength or improved conductivity, but usually the increase in one factor is a trade-off for a decrease in another.
The aluminum is first heated to soften it and then coated with a film of lubricant. A hydraulic or mechanical press pushes against a supporting block that gradually pushes the heated material through the opening of the die, which is a pattern for how the finished product should appear. The pressure of the press causes the heated metal to fill in the empty space in the die and take on the form of the inside of the die. The aluminum comes out the other side of the die in its finished shape.
Different alloys of aluminum are processed at different temperatures. The temperature is measured as the aluminum extrusions exit the die to confirm the proper speed for the process. The aluminum extrusions are sometimes cooled with water or air as they exit the die. The extruded metal goes to a cooling table to further reduce its temperature.
The cooled extruded pieces are placed on stretching equipment to straighten and harden them. Cooled and stretched aluminum extrusions can be cut into whatever lengths are required. Finally, the pieces are aged at room temperature or placed in an aging oven where they are heated to increase hardness and to temper the metal.
Aluminum extrusions are used for many purposes, including things such as display cabinets in stores and the aluminum-frame desks in modern offices. Virtually every type of vehicle contains aluminum extrusions, including cars, boats, bicycles and trains. Home appliances and tools take advantage of aluminum's excellent ratio of strength to weight. Extruded aluminum products weigh less and cost less to ship than those made with other types of metals, yet they still provide long-lasting service.
The increased focus on green building is also leading contractors and architects to use more extruded aluminum products. Aluminum extrusions are flexible and corrosion-resistant. Aluminum is easily recycled and can be used over and over in construction projects.