What Is Aluminum Extrusion？(Definition)
Aluminum extrusion is an aluminum metal forming process. This manufacturing process turns aluminum alloy into an aluminum product with a specific cross-section. This specific cross-section can be solid, hollow or semi-hollow in any shape. Aluminum extrusion is the process of passing an extrusion billet through a steel die with a specific cross-section. A strong pushing force causes the extrusion billet to form an aluminum product with the same cross-section as the die at the die opening.
The process of aluminum extrusion is often explained simply as squeezing toothpaste out of a tube. The tube opening is round, so the extruded toothpaste is a solid cylinder. When the die opening is similarly round, the extruded aluminum product is an aluminum bar.
In life, we commonly see aluminum tubes, aluminum bars, aluminum angles, aluminum channels, and aluminum beams as aluminum products produced through the aluminum extrusion process. In addition to these simple shapes, there are complex designs in industry that require aluminum extrusion manufacturing. More and more products are required to be lightweight, which also makes aluminum products replace steel products.
Different Types of Aluminum Extrusion Process
Hot Extrusion Vs. Cold Extrusion Vs. Warm Extrusion
According to the different temperatures of aluminum extrusion billet, the aluminum extrusion process can be divided into hot extrusion, cold extrusion, and warm extrusion.
| Hot Extrusion | A process in which aluminum billets are heated to a recrystallization temperature range (400-500 degrees Celsius) for extrusion. In this temperature range, aluminum has very good plasticity, increased fluidity, and is easy to form.
The majority of extruded aluminum products are produced by hot extrusion, especially for complex sections as well as large-size sections. |
| Cold Extrusion | A process in which aluminum billets are extruded without heating.
The cold extrusion process is suitable for the production of small-sized parts. The surface finish is better than the hot extrusion. |
| Warm Extrusion | A process in which aluminum billets are heated, but not to the crystallization temperature range for extrusion.
Warm extrusion is not widely used at present. |
Direct Extrusion Process Vs. Indirect Extrusion Process
According to the direction of flow of the aluminum billet relative to the die in the extrusion process, the aluminum extrusion process can be divided into direct extrusion(forward extrusion) and indirect extrusion(backward extrusion). Both production processes are hot extrusion.
| Indirect Extrusion (Backward Extrusion) | The extrusion billet remains stationary and the aluminum is extruded in the opposite direction of the ram movement.
Aluminum bars and aluminum seamless tubes are usually produced by the indirect extrusion method to ensure a more homogeneous internal structure. |
| Direct Extrusion (Foward Extrusion) | Aluminum billets are extruded through the die opening in the direction of the movement of the extrusion billet during extrusion. The majority of extruded aluminum is produced by direct extrusion. We will focus on this process to explain the specific steps. |
- Preheating the steel extrusion die for extrusion production and loading it into the extruder after preheating.
- Preheating of aluminum billet for extrusion. It is transferred into the extruder after preheating.
- A hydraulic cylinder applies pressure to the ram and the aluminum billet is pushed into the container of the extrusion press, which expands and fills the entire container.
- Aluminum is extruded out of the die opening because of the pressure, and the cross-sectional shape of the aluminum is the same as the shape of the die contour.
- The puller grips the extruded profile and guides it forward at the same speed.
- When the length of the extruded aluminum reaches the length of the runout table, it is cut.
- The cut aluminum is mechanically transferred to the cooling table for natural cooling to room temperature.
- The extruded aluminum needs to be straightened.
- The extruded aluminum is cut to the specified length.
What Shapes Can Be Produced by Aluminum Extrusion Process?
The extruded aluminum shape can be hollow, semi-hollow, and solid.
Common & Standard Shapes
You can easily buy some extruded aluminum products in the market, such as aluminum tubes, bars, rods, beams, channels, T-slots, and so on. These we call standard aluminum extrusions.
There is a wide variety of shapes and sizes for these standard aluminum extrusions. For example, aluminum bars come in square, rectangular, hexagonal, pentagonal, etc. Hollow aluminum tubes are also available in square, rectangular, and round shapes.
These standard shapes of aluminum extrusions are used in various applications. Aluminum round tubes and aluminum square tubes are always used in construction. Aluminum rods and bars are used in CNC machining. Aluminum beams and channels are for construction and general industry. The T-SLOTS aluminum extrusions are for DIY framing.
You can have many sizes to choose from the dealers, and there is no minimum purchase requirement.
Custom Shapes
When the standard shape can not meet your use, then a customized aluminum extrusion will be a very good choice.
You can design the cross-section of aluminum according to the requirement of use. The aluminum extrusion process can produce very complex geometric sections. Some are used in construction, some in automotive, and some in industrial products.
FONNOV Custom Aluminum Extrusions And Parts For Our Customers
What Sizes Can Be Produced by the Aluminum Extrusion Process?
The size of an aluminum extrusion product depends largely on the capacity of the extrusion press. The larger the tonnage of the extrusion press, the larger the size of the aluminum cross-section that can be extruded.
| Extrusion Press capacity <20 MN | Suitable for producing smaller cross-sectional profiles. For example, our common door and window frame profiles. |
| 20MN< Extrusion Press capacity <50MN | Suitable for most aluminum extrusions. |
| 50MN< Extrusion Press capacity <100MN | Suitable for producing industrial aluminum profiles with a width of 300-350mm. |
| 100MN< Extrusion Press capacity <150MN | Suitable for producing thick-walled structural aluminum extrusion and aluminum extrusion with a width of more than 400mm. |
Of course, this is not completely absolute, but only an approximate value.
Usually, we consider the size of the extrusion press to be used based on the dimensions of the outer circle of the cross-section. But this is not the only factor. Weight, length, and cross-section design will all be important factors in selecting the right extrusion press. This is why some small cross-sections require larger presses to meet the product requirements.
Dies and Tooling for Aluminum Extrusion Manufacturing
Die is an important part of aluminum extrusion production. Aluminum extrusion production can not be started without a die.
A high-quality die ensures dimensional accuracy and surface quality and can be used for a longer period.
Extrusion dies usually can be solid, hollow, or composite dies.
A die does not mean unlimited use, every die has a certain service life.
Whether they are used frequently or not used for a long time, dies need to be maintained regularly, so that the quality of the extrusion can be guaranteed in every production.
What Are the Benefits of Aluminum Extrusions?
| ALUMINUM EXTRUSION ADVANTAGES | |
|---|---|
| Design | Through the aluminum extrusion process, aluminum can be easily extruded into complex sections. This flexibility allows product designers to create unique assembly features for applications. |
| Weight-Strength Ratio | More and more automotive and transportation industries are pursuing lightweight, and aluminum extrusion profiles can be both high-strength and lightweight at the same time. Multi-cavity design not only reduces weight but also effectively enhances the strength of aluminum to meet the load requirements. |
| Cost | Custom-designed aluminum extrusion reduces the need for secondary machining. |
| Recyclable | The aluminum extrusion profile is 100% recyclable. Recycling and reuse of aluminum reduces resource depletion. |
| Attractive Appearance | The surface of extruded aluminum can be powder coated to get a variety of colors and also can be anodized to get a delicate metallic texture. A mirror-like finish can be achieved through mechanical surface treatments. All these textures and colors make extruded aluminum more harmoniously suited to various applications. |
| Heat Conductive | Aluminum provides both efficient heat transfer performance and a significant reduction in overall system weight. Aluminum can be designed into thermal structures with large surface areas. Aluminum’s high thermal conductivity makes it widely used in heat sinks, and power supply boxes. |
| Low Maintenance | Extruded aluminum is easy to clean, and usually requires only water. If the surface is damaged, some simple sanding will restore the appearance. |
| Corrosion Resistant | When extruded aluminum is exposed to air, a natural oxide film forms on the surface. It effectively protects aluminum from corrosion in the general environment. |
Which Factors Affect Aluminum Extrusion?
Not all designs can be realized by extrusion. Perhaps you have encountered an aluminum extrusion manufacturer who thinks that your design cannot be extruded, or that your design cannot be extruded with the required alloy.
Aluminum extrusion manufacturers consider many factors when reviewing your drawings, including shape, size, alloy, extrusion ratio, tolerances, and yield.
Alloy Options For Aluminum Extrusions
6xxx Aluminum Alloys (Aluminum-Magnesium-Silicon Alloys)
The most suitable alloys for aluminum extrusion are 6063, 6061, 6060, 6082, and 6005. Magnesium and silicon are the main alloying elements.
6063 alloy is mainly used in the construction field, widely used in door and window frames, decorative aluminum trims, and so on.
Alloy 6061 has a higher strength than 6063, and is commonly used in structural components. Its good corrosion resistance and machinability make it the most ideal industrial alloy.
6060 and 6082 are mainly used in European countries. 6060 alloy has a lot of similarities with 6063 alloy, and 6082 alloy has a similar application to 6061.
Alloy 6005 has a good surface finish while maintaining high strength. 6005 is a good alternative to 6061 for industrial parts where a better surface finish is required.
2xxx Aluminum Alloys (Aluminum-Copper Alloys)
The 2xxx alloy used for extrusion is mainly 2024 alloy, with copper as the main alloying element.
Known for its high strength, although not as strong as 7075 after heat treatment, alloy 2024 is also a good choice for high-strength aircraft structural parts.
5xxx Aluminum Alloys (Aluminum-Magnesium Alloys)
The 5xxx alloys used for extrusion are mainly 5083 alloys, with magnesium as the main alloying element.
It has good corrosion resistance and is commonly used in marine engineering where corrosion resistance is required. In addition, its excellent weldability makes it very suitable for the production of pressure vessels.
7xxx Aluminum Alloys (Aluminum-Zinc Alloys)
The main extrusion alloy used in the 7xxx series is 7075. Zinc-magnesium-copper is the main alloying element.
Alloy 7075 is known as the strongest aluminum alloy, and has excellent mechanical properties after heat treatment. It is a commonly used alloy for aircraft components.
Heat Treatment Options for Aluminum Extrusion
The strength of aluminum after the extrusion process is not sufficient for some specific required applications, and further heat treatment is needed to increase its mechanical properties. Temper is a combination of hardness and strength of aluminum after heat treatment.
Some alloys are heat treatable and some are not.
- Heat-treatable alloys: 2xxx, 6xxx, 7xxx
- Non-heat treatable alloys: 1xxx, 3xxx, 5xxx
Upon receipt of your drawing, we will be the first to look at the alloy and temper you requested. When seeing the material 5083T6, this is obviously wrong. The alloy 5083 is non-heat-treatable.
Common Heat Treatment for Alloys
| ALLOY | HEAT TREATMENT (TEMPER) |
|---|---|
| 1xxx | O H |
| 2xxx | T3 T4 T351 |
| 3xxx | O H |
| 5xxx | O H |
| 6xxx | T4 T5 T6 T651 |
| 7xxx | T6 T651 T73 T76 T7351 T7651 |
| HEAT TREATMENT (TEMPER) | DESCRIPTION |
|---|---|
| O | Annealed |
| H | Work-hardened condition, different degrees of hardening are indicated according to the numbers. |
| T3 | Natural aging after solution treatment |
| T4 | Natural aging after solid solution treatment |
| T5 | Artificial aging directly after extrusion |
| T6 | Artificial aging after solid solution treatment |
| T651 | T6 condition plus stress relief treatment |
| T73 | Two-stage artificial aging after solid solution treatment to enhance corrosion resistance. |
Finishing Options for Aluminum Extrusions
Surface treatment of aluminum extrusion can provide corrosion protection or enhance aesthetics. The choice depends on the functional and aesthetic requirements of your product.
Common aluminum extrusion surface treatment include anodizing, powder coating, wood grain finish, polishing and sandblasting.
ANODIZING
Anodizing is the formation of an aluminum oxide film on the surface of aluminum through an electrochemical process. The surface of aluminum will naturally form an oxide film when exposed to air for a long period of time. The difference between an anodized layer and a natural oxide film is that the film is thicker, has higher corrosion resistance, and has more color options to improve aesthetics.
Anodized aluminum extrusion is widely used in window and door frames, heat sinks, and industrial components.
POWDER COATING
Powder coating is a process in which the powder coating is adsorbed onto the aluminum surface by electrostatic action, and then cured by heating and baking to form a uniform protective film on the aluminum surface. This protective film has good abrasion, impact and corrosion resistance. Compared to anodizing color options, powder coating has no limitations for color customization, providing a more harmonious match for the color space.
Powder coated aluminum extrusion is commonly used in outdoor facilities, window and door frames, and architectural aluminum products.
WOOD FINISH
Woodgrain finish is a sublimation process that transfers a woodgrain pattern to the surface of aluminum extrusion to make the aluminum look like wood. Woodgrain aluminum extrusion is perfect for construction, interior design, and furniture manufacturing, giving the color the natural beauty of woodgrain while combining the strength and low maintenance of aluminum.
POLISHING
Polishing can result in a smooth and mirror-like surface on extruded aluminum.
Some polished aluminum extrusion is chemically polished, but most are mechanically polished.
Polished aluminum extrusion is suitable for highly decorative products, such as aluminum frames for shower enclosures, automotive parts, and trailer frames.
SANDBLASTING
Sandblasting surface treatment involves spraying abrasive material onto the surface of aluminum by means of a high-pressure air stream, and this method results in a uniformly rough surface. Sandblasting can do a good job of removing imperfections from the aluminum surface. If there is a subsequent powder coating, sandblasting can increase the adhesion of the coating.
Machining for Aluminum Extrusions
In many cases, aluminum extrusions require further machining to meet assembly requirements. Extruded aluminum has good machinability and is well suited for the manufacture of complex parts or structural components.
Aluminum machining is the removal of excess material through machining methods. It usually involves precision cutting, milling, drilling, etc. Machining usually produces smaller components and parts.
| Milling | The excess material of aluminum is removed by rotating the tool to get the specific shape. Milling is mainly used for machining flat surfaces, slots, and beveled surfaces. |
| CNC Machining | Automated machining by CNC machine tools. A CNC machining center usually contains multiple machining processes, and are capable of machining curved surfaces. It is used to manufacture high-precision parts. |
| Sawing | Extruded aluminum is cut to a specific length by a saw. This is widely used for cut-to-length aluminum extrusion. |
| Turning | By rotating the workpiece, the surface of the workpiece is machined with a turning tool to remove excess material. Turning is mainly used for machining cylindrical parts, such as aluminum tubes. |
| Drilling | Holes are drilled into aluminum by a drill. Drilling is mainly used to process screw holes, through holes and blind holes. |
| Tapping | Machining of internal threads on aluminum with holes by a rotary tool. |
| Grinding | Aluminum surfaces are polished by a high-speed rotating grinding wheel to achieve high flatness and finish. |
| Stamping | Aluminum is stamped into specific shapes by a presses and a die. Suitable for batch processing. |
| Laser Cutting | Aluminum is melted in specific areas by a high-energy laser to achieve cutting requirements. |
Fabrication for Aluminum Extrusions
Aluminum fabrication typically involves bending, welding, and assembling aluminum to make a final product or structure.
| Bending | Aluminum profiles are processed into specific bending shapes without destroying their structural integrity. The aluminum bending process needs to ensure that the profile is bent without deformation, cracking, or surface defects. |
| Welding | Two aluminum materials are joined together by heating and melting. TIG welding and MIG welding are the most common methods of welding extruded aluminum profiles. |
| Assembly | Parts or profiles are assembled into a final product by various joining methods. The joining methods usually consist of threaded connections and rivets, and some decorative assemblies can also be glued. |
What are Aluminum Extrusions Used for? (Applications)
Transportation and Auto Industries
- Automobile body structures, crash beams, door frames, engine supports, and other parts.
- Railway and subway train body and frames.
- Truck chassis and components, trailer rails, and frames.
Building and Architectural Construction
- Door and window frames
- Curtain wall systems
- Railings
- Ceilings
- Partitions
- Various decorative strips
- Roller shutters
- Furniture structure
- Pergola
Aerospace And Defence
- Structural components of aircraft, such as wings, cabin frames, and internal support structures.
Marine
- Support structures, railings, and ladders in offshore oil and gas platforms.
- Hull shells, decks, cabins, and hull support structures
- Ship interiors and equipment, such as railings, stairs, partitions, hatches, and other components.
Energy
- Solar racking
- Aluminum Frame of Solar Panel
- Wind Power Generation
Heat Conduction Applications
- Heat Sinks
- Electronic housings and frames
Consumer Goods
- Bicycle frames
- Camping
Industrial Equipments
- Industrial equipment frames, parts, etc.
Infrastructure
- Railway and subway infrastructure: e.g. track supports, station building frames, etc.
- Airport infrastructure: e.g. corridor bridges.
Outdoor Sports Products
- Fitness equipments and facilities
- Trekking poles, hiking poles
- Ski poles
- Bicycle frames
- Aluminum horse jumps
- Aluminum frames of camping table and chair
Aluminum Extrusion vs Aluminum Casting
| Aluminum Extrusion | Aluminum Casting | |
|---|---|---|
| Process | A heated aluminum extrusion billet is forced through a die to form a long continuous shape with a fixed cross-sectional profile under high pressure. (Like squeezing toothpaste) | Aluminum is melted, and injected into a die, cooled and solidified into the desired shape. (Like homemade jelly) |
| Product Character | Long, uniform cross-section | 3D shape |
| Material Property | Good mechanical properties | Typically low mechanical strength |
| Die Cost | Lower cost | Higher cost |
| Surface Appearance | Smooth surface | Relatively poor |
| Application | Frames, structural parts, long profiles, heat sinks, etc. | Complex shapes with internal cavities, automotive parts, engine components, etc. |
Aluminum Extrusion vs Aluminum CNC Machining
| Aluminum Extrusion | Aluminum CNC Machining | |
|---|---|---|
| Process | A heated aluminum extrusion billet is forced through a die to form a long continuous shape with a fixed cross-sectional profile under high pressure. (Like squeezing toothpaste) | Removing material from a solid block of aluminum using a CNC machine (like making a sculpture) |
| Material Usage | Custom designs can be tailored to the application with high material utilization and minimal waste. | Subtractive process, more material waste |
| Design Flexibility | Limited to uniform cross-section profiles | Flexible, and can create complex 3D shapes |
| Tolerance | Moderate tolerances | High precision |
| Cost | Die cost, lower unit price if quantity meets MOQ. | No die cost, but unit price is higher. |
| Surface Finish | Smooth surface | High-quality surface |
| Applications | Frames, structural parts, long profiles, heat sinks, etc. | Precision components, prototypes |
Working With Aluminum Extrusion for Your Project
Design Aluminum Part
Things to consider when designing an aluminum extrusion part:
- Uniform cross-section
- Consistent wall thickness
- Accuracy and tolerances
- Surface finish
- Application and loads
- Suitable alloys
- Assembly features to minimize secondary operations.
Look Into an Aluminum Extrusion Company
Once the design is complete, it is critical to work with an experienced aluminum extrusion manufacturer. What will a professional extrusion company bring you?
- Tell you if your design is suitable for the extrusion process, and where modifications need to be made.
- Get you a qualified aluminum profile product.
- More experience producing difficult and complex aluminum extrusion products.
- Ensure that the delivered product meets the chemical composition, physical properties, and dimensional tolerances required.
What information do you need to give the aluminum extrusion company?
Drawing include the following details:
- Dimensions and tolerances
- Quality testing standards
- Alloy and temper
- Decorative surface
- Surface treatment
- Application
- Length
Some additional information can help them to understand your needs more clearly.
- Packaging Requirements
- Quantity
- If machining is required, STEP drawings are required.
- Delivery time requirement
All of the above information will help the aluminum extrusion manufacturer to serve you quickly and better.
Brief introduction of FONNOV ALUMINIUM
FONNOV ALUMINIUM has been a professional custom aluminum extrusion manufacturer since 2004. Our fabrication factory provides value-added aluminum fabrication and CNC machining services. FONNOV is focusing on producing high-quality extruded aluminum profiles and aluminum products for auto and electric vehicles, trucks and trailers, trains and subways, ships and vessels, and architectural and building construction.
FONNOV ALUMINIUM will be a single-source aluminum extrusion supplier for your aluminum projects.
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