Extrusion is a process by which a base material is manipulated through a die (mold) to create a desired cross-sectional profile. Used in various ways in construction, there is a plethora of materials to choose from such as aluminum, titanium, and steel. Each of these materials has their own advantages, but aluminum is easily the most commonly used material regardless of if you’re working with direct or indirect extrusion.
The biggest difference between direct and indirect extrusion is the mobile parts and the friction generated. In direct extrusion, also called forward extrusion, a billet is placed in a heavy container and pushed through the die with the use of a ram or screw. Because of the billet’s need to travel the entire length of the heavily walled container in which it is placed, greater frictional forces are generated than in indirect extrusion. In indirect extrusion, however, the frictional forces are eliminated because the billet moves with the container while the die is held stationary by a “stem”.
Custom aluminum extrusion companies choose to use aluminum (the most commonly extruded material) for a variety of reason. The least of these reasons is the simple cost of it over the costs of materials such as steel and titanium. Aluminum can also easily be extruded into different shapes creating a higher variety of custom aluminum extrusions than what is achievable using other materials.
Typically speaking, aluminum is heated to a much lower temperature than steel or titanium. Aluminum will only be heated to between 575 and 1100 degrees Fahrenheit while titanium must be heated to between 1100 and 1825 and steel is heated between 1825 and 2375 degrees Fahrenheit. The lower temperatures along with prices and the easily manipulated shapes makes aluminum the smartest medium for extrusion a workman could make.