Extrusion refers to the method of shaping material like aluminum by forcing it through an angled opening in a mold. The material that is extruded is an elongated part that has the same profile that it has the die opening.
To aid in understanding the aluminum extrusion process think about the Play-Doh(r) Fun Factory and how it works. The Fun Factory is the extrusion press. The handle functions as a ram, and the shape bar serves as the die. Play-Doh(r), in contrast is the aluminum billet. The initial step is to decide on the desired shape and color. The shape is the die, and the color is the temper or alloy. Then, the Play-Doh(r) is put into the chamber of holding, and it is pressed against the handle which forces Play-Doh(r) through the form. Extrusion presses apply pressure to the billet through the ram. The ram stem attaches the dummy block to the end of it. It is “extruded” when Play-Doh(r), appears. Extrusions of aluminum billets are based on similar principles, however, Tamilnadu Aluminium Company utilizes more advanced technology.
The size of the press determines how large the extrusion will be. The longest dimension of an extrusion’s length is its cross-sectional width, i.e. the circumscribed circle. The circumscribed circle is the smallest that can completely cover the cross-section of an extruded shape.
The most important factor to consider in the extrusion process is temperature. It is crucial because it gives aluminum its desired characteristics like quality and hardness.
STEPS IN THE ALUMINUM EXTRUSION PROCESS
- Warm the billets until they are heated to 800-925 deg F.
- When a billet reaches the temperature that it is required It is then transferred to the loader. In the loader, a thin layer of smut (lubricant) is applied to the billet and the ram. The smut serves as a lubricant which acts as a separation agent and keeps the parts from sticking.
- The billet is transferred into the cradle.
- The ram is used to apply pressure to the dummy block that, then, pushes the billet until it’s within the container.
- The billet is pressed against the die with pressure, and shrinks bigger until it meets the wall of the container. As the aluminum is forced through the die, nitrogen liquid moves over a portion of the die in order to cool it. This extends the life of the die as well as creating an inert environment that prevents oxides from forming on the surface being extruded. Sometimes, nitrogen gas may be used instead of liquid nitrogen. While nitrogen gas isn’t able to cool the die, it does provide an inert atmosphere.
- As a result of the pressure applied to the billet the solid, but soft metal begins to compress the die opening.
- After an extrusion has left the press, its temperature is determined using the True Temperature Technology (3T) device mounted on the platen on the press. The 3T monitors the temperature of exit of the aluminum extrusion. To ensure maximum press speeds The primary purpose of temperature measurements is to determine what temperature it is. The alloy determines the extrusion’s departure temperature. The ideal exit temperature for 6063A, 6463Aand 6063A and 6101, respectively is 930deg F (minimum). 6061 and 6005A are respectively 95 and 950 degrees F.
- Extrusions are removed from the die and then pushed into the leadout tables and the puller. This guides the metal on the run-out throughout extrusion. While being pulled, extrusions are cooled with a series of fans along all the length of the run-out cooling table. Be aware that Alloy 6061 can be in the air or water quenching process.
- The billet is not all that is suitable for use. The remainder (butt) contains oxides from the skin of the billet. While the butt is disposed of and another billet is being loaded. The the welded billet will then be used to extrude.
- When the extrusion is at the length that is desired then it can be cut with a profile saw or a shear.
- Metal is transferred (via belt or walking beams systems) from the run-out table to the cooling table.
- When the aluminum is cool, it can be moved across the cooling tables to be stretched. Extrusions are straightened after which ‘work hardening (molecular alignment) is performed. This gives aluminum increased hardness and strength. Find the profile makers of aluminum.
- The next step is cutting. After extrusions have been stretched they are transferred to a table saw and cut to the desired lengths. Depending on the length of the saw the cutting precision of the saw is 1/8 inches or more.
Once the pieces have been cut and shaped, they can be transported on a device and transported to age ovens. The process of heat treating, also called artificial aging accelerates the aging process through reducing the temperature of the oven for an exact period of time.
