Aluminum extrusion is the process by which a billet of metal is forced through a die by a hydraulic ram to create a desired shape. Aluminum can be extruded through either a hot or cold process. The popularity of
aluminum extrusions is unmatched by other alloys, and continues to meet all new manufacturing needs and environmental guidelines.
Types
General extrusion occurs in both a hot and a cold process. The functional difference between the hot, or direct, extrusion process and the cold, or indirect, process occurs in the placement of the billet and the ram. In the direct process, the billet remains stationary and the ram forces it through the die. In the indirect process, it is the die that remains stationary and is pushed by the ram into the billet. In both methods, hardening of the
extruded aluminum can take place either at a naturally-cooling room temperature or by adding additional heat treating.
Identification
While both methods of extrusion are used for various alloys,
aluminum alloys usually rely on the direct extrusion process. Prior to being forced through the die in the direct extrusion process, the
aluminum billet is heated to temperatures ranging from 700 to 900 degrees F. The hydraulic ram then pushes a dummy block into the preheated billet, driving it through a cylinder at a speed determined to generate the necessary heat that will mold it through the die.
Considerations
While the extrusion of aluminum proves to be highly effective, extruding alloys of greater durability are less popular because this is not as economical. These higher-strength alloys are extruded at more than 1,000 feet per minute. More durable alloys need to move at a greater speed in order to contain the heat that is generated, thus enabling them to accommodate the malleability required for extrusion. The casualties of this fast extrusion process often occur because the heat rises so greatly that they weaken and crack.
Significance
From everyday items to the world of tomorrow,
extruded aluminum continues to be the most viable solution for manufacturing needs. At work, at home and at school, from window casings to picture frames to chalk trays, aluminum extrusions can be commonly found in a variety of structural shapes. Most recently, extruded aluminum tubing has been used to form the truss
structures that bind together sections of the International Space Station.
Potential
The use of aluminum as the preferred metal in the extrusion process also proves to be environmentally conscious. Because of the high recyclability of aluminum, and due to its acceptance as a reliable structural metal among builders,
extruded aluminum is a vital part of the current green building movement in the World..