What Is Aluminum Extrusion?
It is a forming process where you force aluminum material through a die. As a result, aluminum material conforms to the shape of the die. Of course, this is due to the shear stress and compressive forces.
The material leaving the die is called extrudate.
Aluminum Extrusion History
Metal extrusion began more than 100 years ago. In the year 1797, Joseph Bramah first did the development of this procedure when he was producing lead pipes. Initially, the process was manual until in 1820 when Thomas Burr was able to complete a production using a hydraulic press.
In 1894, Alexander Dick made some developments and came up with the hot extrusion technique that is now used in this era. Due to the hot extrusion process, manufacturers are able to use alloys that are nonferrous in the process of extrusion.
Extruded Aluminum Shapes
Below are the shapes of extruded aluminum shapes;
Hollow – with this shape, the profile has a single or more openings which can be rectangular, square and much more. A semi hollow extrusion assumes a “C” shape, a small opening is left on the profile but the entire remains closed.
A solid extrusion can be any shape ranging from round bars, rectangular bars and square bars; they are the least complicated profiles. Custom Aluminum Extrusion Shapes that can have a variety of extrusions according to the specifications from the client.
Aluminum Extrusion Profiles
The extrusion process of aluminum can achieve many profiles that can be categorized as hollow, semi hollow and solid profiles. A hollow profile resembles tubes which are either round, square, rectangular, oval or any other shape, an empty space is enclosed.
A semi hollow extrusion assumes a “C” shape, a small opening is left on the profile but the entire remains closed. A solid extrusion can be any shape ranging from round bars, rectangular bars and square bars; they are the least complicated profiles.
Aluminum Extrusion Process
Extrusion Die Preparation
A round shaped die should be machined then heated to about 450-500 degrees thus ensuring metal flow is even.
i. Preheating Aluminum Billet
In an oven, the billet is heated at 400-500 degrees to ensure it is malleable.
ii. Billet Transferred to the Extrusion Press
The billet is transferred mechanically.
iii. Billet Material is Pushed to the Extrusion Press Container
At high pressures, the billet that is malleable is pushed into the container.
iv. Extruded Material Is Pressed Up Against The Die
As the container walls are filled with aluminum material, it is pressed against the die. Therefore, its direction is only on the die openings thus it moves out in an already formed shape.
v. Extrusions Are Quenched
After emerging, the extrusion is held in place by a puller.
vi. Extrusions Are Sheared To Table Lengths
A hot saw is used in shearing.
vii. At Room Temperatures, Extrusions Are Cooled
Extrusions are taken to a cooling plain for them to cool.
viii. Extrusions Are Moved To A Stretcher And Aligned
They are mechanically pulled to make them straight.
Lastly, extrusions are then cut to desired lengths.
ix. Secondary Operations
Here, operations like surface finishing, heat treatment and fabrications are carried out on the extrusion hence boosting properties.
Heat Treatment Of Aluminum Extruded Parts
Aluminum extruded parts can undergo heating which not only improves their ultimate tensile strength but also yield stress. To perform this, extruded profiles are put into ovens which accelerate aging process since they are brought to T6 and T5 tempers.
Accelerated aging process leads to the change in properties greatly on the tensile strength. For instance, an untreated T4’s tensile strength is 35000 psi while a heated T6 has a tensile strength of 45000 psi. Therefore, it is important for a client to understand the right tensile strength the want for their project.
Surface Finishing On Aluminum Extrusion Parts
The reason why surface finishing is of importance on aluminum extrusions is because they enhance the overall appearance. Also, the corrosion properties of aluminum are enhanced. These profiles can undergo various types of finishing which includes the following;
The process is electrochemical which enhances coating of the aluminum extrusion with a surface layer of an oxide. Besides, the oxide layer thickens the aluminum extrusion thus providing an added advantage of corrosion resistance. Also, the surface emissivity is improved and provides a surface that is porous which can accept a variety of dies.
Aluminum extrusions can be cleaned and roughened up using the impact of sand stream at6 higher velocities. Spraying sand on the aluminum surface is aided by the use of compressed air at high speeds. The surface is then given a different degree of roughness and cleanliness hence the mechanical properties are now improved.
Powder is sprayed on the aluminum extrusion through an action of static electricity. On the surface, the powder is uniformly absorbed on the extruded part then cured under high temperatures flattening and baking. This effect is superior compared to wet painting in terms of corrosion resistance, mechanical strength and adhesion.
Factors Affecting Extrusion Of Aluminum Parts
Speed Of Extrusion
Speed of extrusion is directly proportional with the aluminum metal pressure and the inside temperature of the container. For a steady process and generation of a constant segment, the pressure, temperature and speed should be properly associated.
Ratio Of Extrusion
The ration of extrusion of any given shape is an ultimate indicator of mechanical work that should be done during extrusion. In case a section of extrusion ratio is low, the work needed to be done on the metal part of the shape will be less. However, there will be need of more pressure the extrusion ratio is high. Higher extrusion ratios require more pressures that are going to push the metal material through the smaller openings.
Extrusion of lighter aluminum parts require presses that are smaller, however, there are some other conditions demanding greater pressers. For instance, a shape that is larger and thin walled, it is going to demand larger presser capabilities.
A required shape is greater determinant on how costly and easy it would be during extrusion of an aluminum part. With the extrusion process, any shape or part can be produced but there at times exist some limitations. For instance, extrusion of solid shapes is faster and easier compared to the extrusion of semi hollow shapes. Therefore, the complex an extrusion is, the more expensive and harder it will be during production.
It is an important factor when it comes to determining the performance of extruded part. To accurately determine the tongue ratio, the smallest opening to the void is squared. Thereafter, area of the entire shape is calculated then divided with the initial squared value of the tiniest opening to the void. The higher the tongue ratio, the more complex it is going to be during the component extrusion process.
Temperature Of The Billet
The billet temperature enhances proper surface conditions and acceptance tolerance. It is important to have a billet extrusion at the low temperatures that the procedure can admit. In the case of higher temperatures, the metal is going to flow more fluid thus it will resist entering areas of constriction. Subsequently, the dimensions of the shape might fall below anticipated tolerances.
For a suitable extrusion process to take place, t6he aluminum material should one that possesses a good degree of ductility. The aluminum metal grains should not be rigidly locked against each other but they need to slide against each other. The reason behind this is, the material should be forced into the die hence it needs to form a shape or bend.
To create desired properties of strength and durability, aluminum is blended with other metals to gives alloys that meet standards. Some of the alloys may have difficulties when it comes to extrusions. Therefore, a chosen alloy determines the amount of temperature and pressure you need to use during the extrusion process.
Direct Vs Indirect Aluminum Extrusion
It is also referred to as the forward extrusion process. In this process, an aluminum extruder puts heated aluminum in a walled container that is also heated. Thereafter, the metal is forced through the die being aided by a moving ram; during this time, higher pressure amounts are produced. Manufacturers often put blocks between the ram and heated aluminum to prevent any kind of contact between the two.
In this process, the container and the heated aluminum move concurrently while the die remains motionless. To carry out the process, manufacturers use a “stem” which is longer than the container and ensures the ram is in place. The billet is the forced to go through the die. Additionally, this process generates lower friction levels to adequately control heat. Products created by this method are consistent due to a steady exerted force.
Benefits Of Aluminum Extrusions
Depending on the wide range of applications, extrusions stock of aluminum can be created with varied strength levels.
Extrusions of aluminum are flexible thus offering high resiliency levels. These extrusions are able to get a spring back from impact loads thus making them valuable as extruded parts in automobiles.
Compared to other potential options like copper, steel, brass and iron, extrusions of aluminum are light weight hence easy to handle.
Aluminum extrusions have an excellent thermal conduction since they can conduct both heat and cold more efficiently compared to other metals. For this reason, they are ideal in a range of applications that require dissipation of heat.
Aluminum is much way better than a metal like copper when it comes to electrical conductivity. Therefore, aluminum is more cost effective for electrical connectors and the distribution parts on a bus bar.
Without losing its properties, aluminum can be used over and over again for a long time. Shapes of aluminum extrusions are normally created with greater percentages of recyclable content which does not affect the end product.
Different procedures of fabrication are utilized during the manufacture of aluminum extrusion components, stock and custom assemblies. Extrusions of aluminum can be used in section designs which assembly together easily through interlocking.
These shapes and parts of aluminum extrusions can be applied surface treatments which creates the property of reflectance. This property is of advantage when it comes in the lighting applications or protecting places from light, radio waves and infrared radiations.
Through the process of extrusion, complex shapes can be produced which do not demand a connection that is mechanical. Therefore, the end result becomes a profile that is stronger compared to mechanically bonded assemblies.
This property makes it possible for applications involving explosive materials and highly flammable environments.
Applications Of Aluminum Extrusion
It is used in the displaying of equipment like in exhibitions where it makes it easier clients to view and notice. This is because; extruded parts are easier to assemble since the pieces can be considered to interlock.
In the transport sector, weight is major factor. For instance in automotive, trailer weight being kept low disburses more force on moving material than it is on the trailer itself.
Aluminum that is lightweight and stiff becomes the ideal material for canopies applications because they are loaded and cannot weigh much. Also, it can be used during the suspension of ceiling boards and in walls.
Extrusions of aluminum are basically used in most industries in making equipment like work benches, carts and inspection tables. This is because the material is light weight, easy to cut, easy to drill and stiff which makes it ideal.
It is mostly used in electrical systems because its electrical properties of conduction that are excellent. Also, in vehicles, fins can be extruded that makes excellent radiators as they do not weigh much when mounted.
Because of its sustainability, aluminum is environmentally friendly thus it can be reused and recycled easily. It is utilized in this industry during packaging of products and making of the storage bins.
People Also Ask:
Aluminum should be used for extrusion because;
- High levels of strength
- Higher thermal conductivity
- Aluminum offers excellent possibilities of design
- Its machining properties are of top notch.
- It contains corrosion resistance properties that are excellent.
- It is versatile
Aluminum extrusion entails materials of aluminum alloy being forced in a die which has a specified profile that is cross-sectional. An aluminum casting is created by having molten metal poured into molds that have been formed in a desired pattern.
Yes, there is recommended aluminum extrusion thickness. The minimum thickness that can be extruded is 0.025 inches.
The alloy is popular for extrusion since it offers finishes that of high quality thus making it to be a greater option. Also, it is best used in the making of custom designs than any other extruded metal.
The required force for aluminum extrusion is about 100,000 – 125,000 psi.
Yes, the extruded aluminum is straight.