The word “extrusion” comes from the Medieval Latin “extrusio.” “Extrusion” was first used in the 16th century to describe something “extruding,” that is forced, pressed, or pushed out.
Extrusion has since come to be used to describe materials formed through the extrusion process, in which substances like metal or plastic are shaped by forcing them through a die. Aluminum extrusions are among the most common. They are used extensively in construction and manufacturing.
Aluminum aerospace-grade extrusions alone come in dozens of shapes, sizes, and grades. Aerospace manufacturers suit each extrusion to a particular purpose, whether it is as a support, joint, hinge, or something else.
Extrusions can be mass-produced from a single Die, thus saving time and money for manufacturers. “Once a customer has purchased a Die, their ROI compounds with every production run of their custom Extrusion. These Dies can be reused indefinitely, saving them time and money for all future Orders and Uses,” said Jamie Barron, Vice President of New Source Corporation.
The most common aluminum extrusions used by aerospace manufacturers include:
- AND (Army Navy Drawing)
- BAC (Boeing Aircraft)
- LS (Lockheed Martin)
- GS (Grumman Aerospace)
- S (McDonnell Douglas)
While there are many more designers and a plethora of different shapes, these are what are used in aerospace most.
Applications for aerospace aluminum extrusions
As semi-finished parts, extrusions can be machined into any custom shape and adapted for any use. Here are just a few examples of aerospace extrusions by their designations and uses.
AND extrusions
ANDs are the most common shapes. They can be used on any plane as parts for anything from simple racking requirements (eg. building shelves to house kitchen appliances in the cabin) to structural repair to flight-critical purposes.
AND parts can be made in any alloy/temper the end user wishes. There are no restrictions and the drawings do not specify any grade of aluminum. The different nomenclatures can call out many different types of shapes. For example, they can be 90-degree angles, bulb angles, tee shapes, and zees.
BAC extrusions
Boeing parts come in a multitude of shapes and sizes. And, like the ANDs, they can be made in any alloy/temper. Though the drawings were originally published with designated grades, Boeing has since lifted restrictions. For example, they can be Roll form, drawn tubing, aluminum extrusion, rubber or plastic, or titanium extrusion.
LS extrusions
Lockheed extrusions always start with the same prefix (“LS”) and three to five digits follow. The extrusions come in Roll-form, rubber, plastic, and extruded shapes. The alloys/grades are designated by the designer drawings. These can be made in a wide assortment of unique shapes that are all specified by the drawing itself. LS Shapes are typically in support of military applications such as the C-130 program.
GS extrusions
Grumman parts are similar to Lockheed extrusions except that they are coded. Each suffix at the end of a Grumman part calls for the alloy and temper. The actual part is the same but the suffix variation denotes the grade needed.
Grumman extrusions also come in Roll forms, extrusions, and plastic/rubber shapes.
S extrusions
McDonnell Douglas parts follow the same suit as the Lockheed parts. Designer drawings specify all callouts and they come in Roll forms as well as extrusions. It will always start with an “S” and then have several digits after that.
Ordering aerospace extrusions
Defense companies want suppliers to have an ample stock of competitively priced aerospace aluminum extrusions and to fill orders quickly.
While expediency is preferred, quality is most important to aerospace and defense companies. They need extrusions to perform as expected, given their importance to an airplane and its mission.
The best suppliers of aerospace aluminum extrusions ensure that each part has the properties required and that it is delivered as desired. For example, some defense contractors may prefer to stencil identifying information on each extrusion at one manufacturing plant to ensure that the part is used as intended, while another location for that same contractor may expect the same extrusions to be wrapped in plastic without any stencil. A supplier should be able to accommodate a contractor’s requests, adhering to the specifications required by different locations.
A supplier should also have a wide choice of extrusions and a deep supply of each so that a contractor does not have to wait long for their orders.
“An Extrusion is a foundation that will always be relevant, regardless of the Plane, End-Use or Application,” Barron said. “Due to their fluid and dynamic natures, you can make a specific Extrusion for whatever your need may be.”