Extrusion is the process of shaping a material like aluminum by forcing it to flow through a shaped opening in a mold. The material that is extruded is an elongated part that is the same in shape as its die opening.
To better understand the process of aluminum extrusion, think about an Play-Doh(r) Fun Factory and how it functions. The Fun Factory is the extrusion press. The handle serves as the ram and the shape bar is the die. Play-Doh(r) is on the other hand is an aluminum billet. The first step is choosing the shape and color you want to use. The shape is the die, and the color is the temper or alloy. The Play-Doh (r) is then inserted into the container that holds it. Pressure is then applied to handle which forces PlayDoh(r), through the shape. The extrusion press is able to apply pressure to the billet using the ram. The ram stem connects the block with the dummy to the other end of it. The billet is “extruded” when Play-Doh(r) appears. The same principles apply to extrusions made from aluminum billets but far more precise and advanced technologies are employed by Tamilnadu’s aluminium manufacturer.
The dimension of the press is a factor in the amount of material an extrusion can be produced. The longest dimension of any extrusion is its length across the cross-section, i.e. it has to be contained within the circumscribed circle. A circumscribed circle is the largest circle which completely covers the portion of an extruded shape.
The most crucial thing to consider in the extrusion process is temperature. The temperature is crucial because it gives aluminum the desired qualities like finish and hardness.
STEPS IN THE ALUMINUM EXTRUSION System
- Billets should be heated to about 800-925 degrees F.
- After a billet reaches the temperature desired and is then transferred to the loader, where an smut-like film or lubricant is poured on the billet as well as to the ram. The smut acts as a lubricant that acts as a separating agent that prevents the pieces from sticking together.
- The billet then moved to the cradle.
- The ram is used to apply pressure to the dummy block. This, in turn, pushes the billet until it’s within the container.
- The billet is compressed against the die under pressure and becomes smaller and larger until it reaches the wall of the container. In order to chill the aluminum, liquid nitrogen is circulated through the die as it moves through. This prolongs the life of the die and creates an inert environment that prevents oxides from forming on the form being extruded. In some cases nitrogen gas is utilized as an alternative to liquid nitrogen. The nitrogen gas doesn’t cool the die but does create an inert atmosphere.
- Because of the pressure added to the billet The hard, yet soft metal starts to squeeze out the die opening.
- The temperature of the extrusion as it exits the press can be determined using True Temperature Technology (3T) which is mounted to the platen. The 3T records exit temperature of the aluminum extrusion. The main purpose of knowing the temperature is to guarantee the highest speed of press. The target exit temperature for an extrusion is dependent upon the alloy. For example, the targeted temperatures for exiting the alloys 6063, 6463 6063, 6063A, as well as 6101 is 930deg F (minimum). 6061 and 6005A are respectively 930 and 930 degrees F.
- Extrusions are pushed out of the die and then pushed into the leadout tables as well as the puller. This guides the metal along the run-out during extrusion. While being pulled, extrusion is cooled by several fans that run along all the length of the runout and cooling table. (Note: Alloy 6061 is water quenched and air quenched.)
- Some of the billet can be used. The butt (remainder) is comprised of oxides derived from the skin of the billet. As the butt is being removed, another billet is loaded. The formed billet is used to extrude.
- Once the extrusion has reached a desired length, it is cut with a profile saw or shear.
- Metal is transported via belts or walking beams from the run-out area to the cooling tables.
- Once the aluminum has cooled it can be moved across the cooling tables and stretched. The extrusions are straightened and “work hardening” (molecular alignment) is done. This gives aluminum an enhanced hardness and strength. Make sure to check Aluminium extrusion manufacturers in india.
- The next stage is sawing. Once extrusions are stretched they can be moved to a sawtable , and then cut to the desired lengths. Based on the size of the saw the cutting precision of the saw is 1/8 inch or greater.
After the pieces have been cut, they’re placed onto a moving device and then placed in age ovens. Heat-treating or artificial aging hardens the material by speeding up the maturing process in the controlled temperature of an amount of time.
