The construction, aerospace, marine, and military industries among others heavily rely on aluminum extrusion products. Extruded aluminum is lighter and that benefits airplanes flying in the skies for a balanced weight. Buildings on the other hand require strong metals for longevity. Aluminum extrusion aids in the development of such strong metals.
According to (Metal Supermarkets, 2015), aluminum extrusion is a process used to create cross-sectional aluminium profile products. The metal is sourced while raw and converted into strong and durable aluminum products. This happens by passing a mass of raw aluminum billet via a die opening.
The aluminum billet passes through the die under high pressure. This is because the die opening is considerably smaller than the aluminum billet passing. For that reason, the aluminum mass is put under pressure. The output is high-quality aluminum extrusion products that assume the shape of the cross-sectional die openings.
Some experts liken the aluminum extrusion process to getting toothpaste out of a tube. Similarly, the aluminum billet is squeezed out of a die and this turns the metal into consumer goods. The demand for extruded aluminum continues to rise by the day.
Extrusion can be done directly or indirectly. Direct extrusion happens with a fixated die head. Then, aluminum billet is pushed through it by a conveyor ram. Conversely, indirect extrusion happens with a moving die and a pivoted billet. The latter is sometimes done to minimize costs.
The Aluminum Extrusion Process
Direct and indirect extrusion processes are both done in stages. While there might be two or three slight differences, in the two processes, most of the others are identical. The decision on whether to go direct or indirect relies on the end product required. Some shapes are better made through direct extrusion while others are better through the indirect process.
Besides, each of the two processes has pros and cons. For instance, it may cost less to use the indirect process compared to the direct process. And that’s why some operation managers will go for that option. Other times, the direct extrusion option is inevitable. let’s go through the aluminum extrusion stages.
- Die openning
The die determines the final product’s shape. Die openning involves giving the die a specific shape. This means that any aluminum that passes through the die will assume its shape.
- Billet preparation
When aluminum is acquired raw, it isn’t ready for extruding. To prepare the metal, aluminum is heated to at least 750 degrees (F). But the heat is kept below 925 degrees (F) to avoid overheating the aluminum. This is enough temperature to melt the aluminum.
After that, smut is applied to both the liquid aluminum and the ram. Considering liquid metal is sticky the smut ensures the two do not stick together. As a result, the billet will move swiftly through the die without sticking on the ram.
- Billet extrusion
The billet is forced through the die by the ram. This happens under high pressure. Under these conditions, its’ very likely for oxides to be formed. This is prevented through the use of liquid nitrogen. The coolant ensures that the die doesn’t overheat to produce unnecessary oxides. Besides, the die will last longer if cooled enough. That means more aluminum will be extruded.
Aluminum extruders are equipped with a variety of extrusion press machines. The tonnage of the extrusion press machine represents the extrusion force. The common tonnage of aluminum extrusion press machine is 800T, 1000T, 1200T, 1800T, 2300T, 2800T, 3600T, 4000T, 5000T, 8000T and so on. A correct aluminum extrusion press machine to be used depends on the cross-sectional dimensions of the aluminium profile.
- The cooling process
As the extruded aluminum leaves through the die, it’s passed to a cooling table. There, aluminum comes to contact with air. Sometimes, the extruded aluminum may be exposed to water. The decision to choose between water, air, or both solely relies on the expectations of the final aluminium profiles.
- The straightening process
After the extrusion process passes the cooling process, the aluminum is released for strengthening. This is a stretching process that ensures the extruded aluminum leaves for the destination while in its hardest, strongest, and finest stage. This means that any deformities that might have occurred in previous stages are taken care of.
The next destination would be cutting the long aluminium profiles into desirable length. A circular saw is used for this process. By the time it’s done, the aluminum extrusion profiles would be ready for finishing before dispatch for sale.
- Finishing & fabrication
This is the final stage in the extrusion process. The extruded aluminum is coated and fabricated using the latest technology. At this point, the products are ready for supply to warehouses and clients. The aluminum extrusion profiles are designed as per client requirements.
What kinds of shapes can be extruded?
The aluminum extrusion process is an interesting one. Different custom shapes are extruded and this depends on the client’s demands. Once the specific requirements have been laid down, the extrusion die is designed to suit the demands. Here are some of the aluminum extruded shapes that you always see.
Aluminum tubes
Aluminum tubing is a common extruded shaping process. This will give you many tube shapes. It may be a rectangular, circular (round), square, oval, hex aluminum extruded shape. Aluminum tubes have elongated bodies with the inside hollowed.
Extruded aluminum products made of this shape are mostly used in the mining industry. Other applications include lighting and the assembly of hardware joints. The space inside makes it flexible and increases the aluminum’s strength to weight ratio. These metals also form good conductors and the finishing makes up for great reflectors.
Aluminum angles
These angles look like half or quarter of the strong rectangular tubes. They assume the shape of a triangle without a hypotenuse. The L-shaped aluminum are corrosion resistant. Their shape also makes them strong and long-lasting.
These kinds of shapes are also used in the construction industry. Offices are partitioned using these kinds of extruded aluminum in some parts of the world. Besides, they’re used together to form stronger aluminum. The angles can also be bent by creatives to make artwork.
Aluminum beams
These are more complex aluminum shapes. They’re made from a combination of other shapes. In most cases, the angles are used together to make this strong shape. Beams are very strong yet light enough not to cause unnecessary pressure when used for construction.
There are different types of aluminum beams. You can have H, T, or C-shaped aluminum extrusions. Each of the shapes has benefits over the other. When using these shapes, consult with an expert to know which one suits your situation best. That way you’ll get the best out of your aluminum beams.
Aluminum channels
Channels are mostly U-shaped aluminum products. One of the sides may be longer than the other or they may be balanced. These channels are used for various purposes including framing and making car bumpers. The aluminum extrusion process can be used to make just about any kind of desirable shape. All the manufacturer has to do is to set the die to assume the shape the client wants.
Aluminum Extrusion Design Guide
When it comes to actual extrusion, details matter. That’s why you must be inch-perfect with your execution. The first step in getting your extrusion right is by using the right dimensions. This involves proper research and workmanship.
Another thing to note is the specific surfaces that bear cosmetic significance. After the extrusion process is complete, one or two surfaces will bear cosmetic importance. You have to establish which one is just about when you’re starting.
When developing specific shapes, like circular ones, you have to be keen on the sizes. This is because there’s a limit to which you can set your die. The part sizes should be within that limit at all times. That way, you’ll have results equal to expectations.
When it comes to the minimum wall thickness, the dimensions are determined by the alloy type. If gotten right, the end products tend to be more effective in terms of functionality. The reverse is true. You’ll get less effective products if you get your thickness requirements wrong.
The extrusion shapes must also be wisely selected. You can opt for solid, semi-hollow, or hollow shapes. Sometimes, a combination of two or three is better depending on the purpose of the product. Besides, you must be keen on the uniformity of the walls. That means having balanced sides with the same thickness.
Another thing to factor in is the joining methods you’ll use. There are three options one can use including the sliding fit and interlocking. The third option is the dovetail fit. While at it, you can go for a round or sharp corner. The choice you go for should always be advised by the work you wish accomplished.
When combining shapes, you have to consider the tongue ratio. There are three of them, i.e. 3:1, 5:1, and 8:1. The ratios are easy, challenging, and difficult in that order. That means the 3:1 combination is the easiest while 8:1 is the most difficult.
Other important considerations include lead times and costs. The time taken to complete an extrusion has a direct impact on the overall cost incurred. Some shapes like asymmetrical take longer to complete extruding. That means you’ll incur more costs.
What Alloys are best for extrusion?
Alloyed aluminum is preferred over pure metal for various reasons. One of the benefits of alloying is to increase the aluminum’s corrosion resistance. Besides, alloyed aluminum offers better workability as compared to one that’s not. The aluminum alloy also has a higher strength level compared to those that aren’t alloyed.
When it comes to alloys, there are specific ones that offer better delivery. According to most experts, the 6000 series do a better job. The best of these series include alloy 6061, 6063, 6005 and 6082.
These series have unique features and different impacts on the extruded aluminum profiles. But one that stands out is their corrosion resistance impact and strength.
Owing to these slight differences, you should consult with your provider/client before choosing the specific alloy series to use. Each of the series has one or two strengths over the other. That’s why a client has to be clear on what they want before an alloy is settled on. That way, the expert will go for the best option that suits the buyer’s needs.
Benefits (Advantages) of Aluminum Extrusion
- Boosts strength
Extrusion is one of the surest ways to boost the aluminum’s strength.
There are different ways extrusion is applied to boost the aluminum’s strength. This depends on the need. Sometimes internal reinforcement is used and the walls could be used for strengthening some other time.
- Reduces weight
As the raw aluminum is passed through pressure, the weight is significantly reduced. This reduces the overall weight. The final extruded aluminum profile comes out lighter.
- Durability
Extrusion involves alloying which helps make the aluminum anti-corrosive. As a result, the extruded aluminum will last longer. Even if exposed to extreme weather conditions, the extruded aluminum will withstand the pressure and will not be destroyed for the longest time.
- Non-sparking
Some metal application in highly flammable areas is inevitable. For instance, trucks that move flammable substances are made of metal. Extrusion aluminum helps minimize the metal’s reactivity with the flammable substance. That way, the chances of explosions happening are very high.
- Sustainability
First of all, extrusion aluminum applies the use of recycled aluminum. That saves the environment from increased degradation. Besides, the aluminum itself doesn’t degrade easily. It lasts long and that means that less waste gets to the environment. For that reason, you have environment-friendly extruded aluminum products.
For the client, it will help save money. It will take time before replacing your products or having to maintain them. For that reason, you’ll have an easier time budgeting.
Heat Treatment after Aluminum Extrusion
Thermal treatment starts immediately after extrusion. Two things happen in this stage. The first process is solution treatment. After that happens, age hardening follows through. The processes involve other sub-processes in which heating is done twice. Between these two heating processes is a quenching process.
The aluminum extrusion is heated to a specific temperature range. Then, it is passed through a quench tank.
The quench tank has to be kept in the best working condition. For that reason, water is replaced now and then. This means every metal that passes through the system is in its best condition.
In all these stages, well-mixed solutions are used with different heat combinations. This helps the aluminum alloys as well to harden. This also boosts the aluminum’s strength and longevity. As such, the final aluminum extrusion product can last and serve the client for the longest time possible.
The aluminum alloy has its certain strength, but its mechanical properties can be largely improved by further heat treatment after extrusion. This is called the temper, such as T4, T5, T6 we always see. For example, 6063-T5 indicates the use of 6063 alloys and a T5 temper, which means the aluminum extrusion is thermally treated (T) after being extruded, and then artificially aged after cooling from an elevated temperature shaping process(5). 6061-T6 indicates the use of 6061 alloys and a T6 temper, which means the aluminum extrusion is thermally treated (T) after being extruded and then solution heat-treated and artificially aged (6).
Finishing Options for Aluminum Extrusions
Finishing serves two main purposes. That includes enhancing the final appearance. That means that a well-finished aluminum extruded profiles will look better than that which is not. Besides, a well-finished aluminum extrusion product will last longer because most finishes enhance anti corrosiveness. Here are some of the best finishes you can try out.
- Powder coating
A solid powder is applied on top of the extruded aluminum profiles. This shields the aluminum from corrosive action among other wear and tear agents. This is done during the oven process as the extruded aluminum is prepared for supply.
Sometimes, extruded aluminum profiles are used in industries that involve emissions. Powder coating helps with compliance to meet the standards required. In these cases, the environment is a major conversation. For sustainability purposes, powder coating is used to keep the metal intact and minimize emissions to the environment.
- Anodizing
This is another popular finishing option utilized by aluminum extrusion companies. The electrochemical process offers increased surety by providing an additional shield to the aluminum extrusion surface. The benefit of anodization is that it accepts many metallic colors. Besides, all aluminum alloys can be anodized. This is a common finishing option for aluminum extrusion products.
- Sublimation woodgrain finish
Woodgrain effect is a special finishing option. In this type of finishing, woodgrain is put into a sublime film of art. This is a chance for the creatives to showcase their talent. Once the art has been drawn, sublimation allows the transfer of the art to the aluminum extrusion surface.
In most cases, sublimation is meant for aesthetic purposes. This type of finishing also has an impact on the longevity of the aluminum. That means it will last longer considering it’s shielded by another substance on top.
- Mechanical finishes
This is also a good alternative. After buffing is done, the aluminum extrusion is either ground or sanded to give it a smooth or rough finishing depending on what the client wants or needs. Two things can be achieved by this. One, the aluminum extrusion is prepared for better aesthetic finishes. Or, it could be to enhance the surface quality of the aluminum extrusion product.
With better quality, the extruded aluminum becomes a better one. The client will therefore get better value for their money. The long-lasting aluminum extrusions will serve a lifetime and will only require repair, maintenance, or replacement of the aluminum product.
- Liquid paintings
Most products are painted after production for aesthetic purposes. Different colors are applied to the extruded aluminum profiles. This provides a buffer against corrosion as well. For that reason, the aluminium profile products will last longer and cost less for maintenance.
A long-lasting aluminum extrusion ensures that the purpose is served well. For a while, the aluminum metal will be productive and efficient.
Machining and Fabrication for Aluminum Extrusions
There are different types of aluminum extrusion products. You have simple ones and those that are complex and will require additional processing after extrusion. Simple ones are turned into complex structures through machining and fabrication.
Machining allows you to cut these hard aluminium products into simpler parts. Once that’s done, fabrication facilitates joining the parts into complicated final product.
Aluminum passes through different stages during machining and fabrication. Some of them include countersinking, laser cutting, laser etching, deburring, drilling, tapping, knurling and CNC milling. Once mechanical joints have been put together, welding is also done. This helps bond joints to come up with delicate and more complex structures.
Through machining and fabrication, strengthening is done and better products are manufactured. Such products are used in construction for support considering they’re strong enough to handle the pressure.
What are Aluminum Extrusions Used for? (Applications)
Different markets can benefit from aluminum extrusions. It could be individuals, companies, or industries. The demand for these products has been on a rise. Here are some of the specific applications for aluminum extrusions.
- Transportation industry
Aluminum extrusions are an important inclusion in this industry thanks to their strength. Both the moving vessels including cars, boats and carriers are made of aluminum extrusion products.
- Construction industry
Building material must be strong enough to support the weight it carries. For that reason, aluminum extrusion products are preferred to other metals. They also last and that means buildings that will last long enough.
- Shielding products
One of the stand out qualities of aluminum is its reflective power. For that reason, the metal is used for making shielding products.
- Electric wiring
The metal is non-magnetic and therefore used to house electric wires.
Summary
Aluminum extrusion is the process through which raw aluminum is converted to extrusion profiles and supplied for consumption. The process is done in different stages that involve different processes and the use of varying chemical combinations. Besides, different finishing options are applied to make the consumption of the products ready as well as long-lasting. Once at the hands of the consumer, the client can use the products for different functions.