Our last blog focused on the initial steps in the aluminum extrusion manufacturing process. The design is finalized, extrusion die fabricated, a production plan developed, an aluminum billet is heated and forced through the die forming the desired design. This post will focus on the final production steps of the aluminum shape or tube.
Press Quench
The 6061-T6511 aluminum extrusion exits the extrusion press at 950-1000 degrees F. It is cooled rapidly to less than 400 degrees F. The aluminum extrusion is cooled with either forced air fans, an air/water mist, or water spray. Our goal is to cool down the aluminum extrusion within 1 minute of exiting the front of the extrusion press. The method of cooling utilized is determined by the size and design of the extrusion. Small, thin wall parts are cooled with a fan. Large, heavy extrusions are cooled with a heavy water spray. Cooling rapidly helps to ensure that the minimum mechanical properties the design engineers expect are achieved.
Stretching
After the extrusion is rapidly cooled it is transferred to a cooling table and allowed to room temperature. The aluminum is then ready to be stretched. Stretching is required to straighten the extrusions and to also relieve stresses in the metal from the aluminum being forced through the extrusion die at high pressure and temperature. In some sense, it is like pulling salt water taffy. The physical dimensions of the aluminum extrusion become slightly smaller when it is stretched.
Rough cut
After stretching the aluminum shapes and extruded tubing is cut to length. For customers ordering parts longer than 60”, the extrusions are cut to their final length. For customers requiring pieces shorter than 40” the extrusions, the extrusions will be “rough cut” to approximately 144”. After artificial aging, they will be sent to one of our precision saws to be cut to their final length. The extrusions are placed in a steel aging rack.
Artificial Age
Artificial aging (aka age hardening) is the final thermal process. The aluminum extrusions are placed in an oven at 350 degrees F for 10-12 hours. During the aging process, metallurgical changes in the aluminum occur and it’s tensile & yield strength increase and elongation decreases.
The aluminum extrusion manufacturing process described in our last two blogs can be thought of as Aluminum Extrusion 101. Each order we produce starts with the basics and adds the details each of our customers requires. Contact us today for your customized aluminum extrusion production plan.
