How to Bend Aluminum
The bending process for aluminum is both practical and cost-effective. It offers design flexibility, integrated functionality, aesthetic appeal, and the ability to create intricate geometries. One of aluminum’s most remarkable attributes is its formability, and one of the primary methods for shaping this metal to your desired configuration is through bending. During the aluminum bending process, mechanical force is employed to transform the material into various shapes. However, it’s important to note that not all aluminum alloys and temper conditions are equally suited for bending.
In this article, we will delve deeper into the aluminum bending process and explore the material characteristics that make some alloys and tempers more conducive to bending than others.
3 Key Factors Affecting The Aluminum Bending Process
The bending process for aluminum is influenced by several factors that can affect the outcome of the operation. These factors play a significant role in determining the quality of the bend and whether it can be accomplished successfully. Here are some of 3 key factors affecting the aluminum bending process:
Formability refers to the ability of aluminum to be bent without cracking or breaking. Aluminum alloys are generally known for their good formability, which makes them suitable for bending processes. However, it’s essential to note that different aluminum alloys exhibit varying levels of formability. Some may be more challenging to bend than others, depending on their composition and mechanical properties.
Elongation is a measure of how much an aluminum material can stretch before it breaks. Aluminum alloys with a higher level of elongation are typically easier to bend because they can deform and stretch more before reaching their breaking point. Higher elongation is a desirable characteristic for materials intended for bending applications. Aluminum Alloy Characteristics Table
Read More: Importance of Elongation in Aluminum Bending
Bend Radius and Thickness
The thickness of the aluminum material plays a significant role in the bending process. Thicker aluminum materials generally require more force to bend and may be more resistant to achieving tight bend radii. On the other hand, thinner aluminum materials are easier to bend and can accommodate larger bend radii with less force. The choice of bend radius, based on the project’s requirements, can influence the ease or difficulty of the bending process. Approximate minimum radii for 90 degree cold bend of aluminum alloys table.
Aluminum Sheet Bending Coefficient Table
|Aluminum Sheet Thickness(mm)||Bending Angle(°)||Bending Coefficient(mm)|
These factors highlight the importance of selecting the right aluminum alloy, understanding its elongation properties, and considering the material’s thickness and bend radius when planning bending operations.
How Do You Choose Aluminum Alloys For Bending?
When it comes to choosing aluminum alloys for bending, you should consider several factors, including the alloy’s mechanical properties, temper, and specific bending process. The choice of alloy and temper depends on your project’s requirements and the desired results. Here are some considerations for selecting the best alloys for bending:
Considerations 1: Temper Selection
Softness and Ductility: Aluminum alloys that are soft and highly ductile are generally easier to bend without cracking. Pure aluminum (alloy 1100) is an excellent choice in this regard, as it is very soft and malleable. However, it may lack the strength required for some applications.
- 3xxx Series Alloys: The 3xxx series aluminum alloys, such as 3003 and 3004, are often used for bending due to their excellent formability. These alloys are known for their moderate strength and good corrosion resistance.
- 5xxx Series Alloys: Some of the 5xxx series alloys, like 5052 and 5083, are also suitable for bending. They offer a good balance of strength and formability, making them a popular choice for various applications.
- 6xxx Series Alloys: 6061 is indeed known for its higher tensile strength and hardness compared to 5052 and 3003. This increased rigidity can make bending 6061 aluminum more challenging.
The primary reason for this difference in rigidity is the alloying elements. 6061 aluminum has a significant amount of silicon and magnesium, which contribute to its higher strength and hardness. On the other hand, 5052 and 3003 contain lower amounts of these elements, making them more formable and easier to bend.
While it is not impossible to bend 6061 aluminum, it may require more force and specialized equipment, and it is more prone to cracking during the bending process. The bend radius and bend angle that can be achieved with 6061 aluminum may be more limited compared to alloys like 5052 and 3003.
Considerations 2: Temper Selection
Temper Selection: The temper of the aluminum alloy significantly affects its suitability for bending. Tempers like O (annealed) and H32 (quarter-hard) are often preferred for bending, as they are softer and more ductile. H14 and H24 tempers can also be suitable for certain applications.
Considerations 3: Aluminum Bending Process
Bending Process: The choice of bending process (roller bending, press bending, draw bending, stretch bending, etc.) can also influence the selection of the alloy and temper. Some processes may require alloys with specific characteristics, so it’s important to consider the bending method in your decision.
Avoid High-Strength Alloys: High-strength aluminum alloys, such as those in the 7xxx series, are not ideal for bending, as they tend to be less formable and more prone to cracking during the bending process.
Consult with an Engineer: For specific projects, it’s advisable to consult with a materials engineer or metallurgist who can provide guidance on the most suitable alloy and temper for your bending needs.
Aluminum Bending Process: 4 Best Ways
Aluminum alloy extruded profiles are widely used due to their good plasticity, lightweight, corrosion resistance, high specific strength (2xxx, 6xxx, and 7xxx series aluminum alloy materials can be aged and strengthened to obtain higher strength), surface treatment, and other characteristics. Bending forming is widely used to produce various bent parts, which are widely used in rail transit vehicles, aerospace equipment, logistics transportation rail frames, car and ship frames, building curtain wall structural parts, medical equipment slide rails, home decoration, and many other fields. The design requirements of bent parts are also diversified and functional. With the continuous improvement of science, technology, and process equipment, the bending process has also shown diversified development.
According to the different bending equipment and bending process principles, the aluminum extrusion bending process can be divided into: stretch forming (two-dimensional, three-dimensional), roll bending forming, press bending forming, and rotary bending forming. According to the shape of the workpiece, it can be divided into two-dimensional curved workpieces and three-dimensional bending workpieces in space.
Best Ways 1#: Stretch Forming Process
Working principle of stretch bending forming (two-dimensional) The stretch bending process is basically divided into 3 steps:
- Step 1#: the stretch bending machine‘s stretching cylinder clamps the material and applies pre-stretching force to the profile to reach the material’s yield strength.
- Step 2#: the stretch forming machine’s rotary cylinder is loaded with bending rotation, and the stretching cylinder sets the axial tension according to the program so that the profile moves around the bending mold to form the material.
- Step 3#: add supplementary stretch forming according to the deformation and rebound of the material.
During the stretch bending forming process, while the workpiece is being bent, the stretching cylinder always exerts axial tension on the workpiece, and the elongated part of the material length is always compensated by the pulling cylinder. This avoids the tendency of the material to wrinkle and can obtain good results curvature effect.
Read More: Stretch Forming Process
Host of three-dimensional stretch forming machine
The main frame of the three-dimensional bending equipment consists of a welded body frame structure installed on the foundation:
- The main frame is used to support the rotatable stretching rocker arm 2 and the hydraulic cylinder. A working platform for placing molds is installed on the top of the frame.
- The two stretching cylinder brackets are respectively installed on the upper part of the rocker’s arm and are electrically positioned through an electrically driven spiral guide rod to adapt to workpieces of different lengths. Each rocker’s arm is equipped with a tensioning cylinder.
- The twisting of the part is effected by a hydraulic motor with a gearbox mounted behind the stretching cylinder.
- The stretching cylinder is mounted on the bracket via a universal joint that allows the clamp jaws to rotate freely forward or backward.
- The clamp lifting cylinder realizes the gradual lifting of the stretching cylinder during the stretching process. The clamp-pitching cylinder can make the stretching cylinder pitch up and down. All the actions of the kinematic pair on the bracket (stretching-lifting-pitching-rotation) make the workpiece During the entire forming process, the three-dimensional mold surface is subjected to tangential stretching to form a three-dimensional three-dimensional workpiece.
Read More: Stretch Forming Machine
Best Ways 2#: Roll Bending Process
- Working principle of roll bending: Roll bending machines (Commonly called aluminum bending machines) are generally divided into vertical aluminum bending machines and horizontal aluminum bending machines. The vertical aluminum bending machine is easy to load and operate, and for long workpieces, the horizontal type should be used. The process position of each axis of the aluminum bending machine is precisely controlled by a servo motor. The hydraulic motor system drives the linkage of each axis, and the servo motor is controlled through a programmable controller (PLC). While the equipment roller shaft is bending the workpiece, the encoder on the equipment monitors the arc length of the workpiece roll bending in real-time and feeds the data back to the system. The equipment performs multiple reciprocating roll bending or multi-radius roll bending trajectories according to the set program sports.
- Characteristics of the roll bending forming process: Aluminum bending machines are generally used to make single arc workpieces. The mold production cycle is short, the investment cost is low, and the operation is simple. For multi-arc workpieces, CNC aluminum bending machines can achieve the multi-arc bending requirements of the workpiece. However, due to the differences in material hardness of the aluminum profiles themselves, and the different deformation degrees of each arc segment of the multi-arc workpiece, uneven rebound, the shape of the workpiece during production the consistency is not good and requires manual correction later. The roll bending process is suitable for the production of large batches of single-arc workpieces or small batches of multi-arc workpieces.
Question 1: Why Should Modern Aluminum Bending Machines Be Driven By Servo Motors?
Modern aluminum bending machines (roller bending machines) all use high-torque and high-precision servo motors for all drives. For example, BIT’s PBA series aluminum bending machine uses up to 15 servo motors on a customized machine.
Servo motors can provide high torque and accuracy for the operation of mechanical equipment. Servo motors can achieve precise positioning of speed, torque, and position when controlling the movement of mechanical components. Compared with stepper motors and hydraulic motors, servo motors do not suffer from out-of-step problems and can ensure operating accuracy even after working for a long time.
Question 2: Variable Curvature Bending And Multi-Arc Bending
The PBA aluminum bending machine is controlled by CNC to precisely control the accuracy of bending and accuracy of repeated positioning, thereby being suitable for the production of large batches of single-arc and multi-arc workpieces. Bendable shapes: C-shape, U-shape, 3R-shape, ellipse, and various arcs with variable curvature symmetrical on both sides; parabola, Archimedes spiral, and various asymmetrical arcs with variable curvature.
Best Ways 3#: Press Bending Forming Process
- Working principle of press bending forming: Press bending forming uses a hydraulic press to apply pressure to the aluminum profile, and the bending forming die produces a bending moment on the aluminum extrusion, causing the aluminum extrusion to bend to form a certain angle and curvature.
- Press bending forming process characteristics and key technologies: Both L-shaped and S-shaped aluminum alloy profile bending parts can use the press bending forming process. Due to the different aluminum extrusion profile sections and shapes, the rebound amount of the bending forming mold for various press bending forming parts is designed differently, it is necessary to explore the rebound amount through continuous bending process tests and obtain a reasonable mold bending surface after several mold modifications.
Several key technical points of the press bending forming process:
- The design of the bending mold must fully consider the deformation trend and rebound amount of the aluminum extrusion.
- Since aluminum alloy profiles have a hollow cavity structure, reasonable filler selection is the key to press bending forming.
- For aluminum extrusion profiles with asymmetric cross-section shapes, effective measures to prevent side bending must be fully considered when bending.
Best Ways 4#: Rotary Bending Forming Process
Profile bending is a comprehensive technology. Various bending principles need to be understood thoroughly, and process designers need to continuously summarize the experience and accumulate in their work over a long period of time, in order to adopt effective and reasonable bending methods for various bending workpieces arc production programs.
The four bending processes introduced above are currently the most commonly used aluminum bending methods for aluminum alloy profiles. In actual process development, the specific process to be used needs to be comprehensively analyzed based on the design and theoretical calculation of the aluminum bending workpiece. It also needs to be combined with various compare experiences with similar workpieces, list the problems expected to occur in curved parts in the early stage of mold or tooling design, analyze them based on each aluminum bending process method, and take corresponding measures to deal with the problems that occur in bending when designing tooling question. For example: the aluminum profile breaks after bending.
Bending Aluminum Without Breaking It
Bending aluminum is a common process in various industries, but it comes with the risk of cracking or breaking the material. Bending aluminum without breaking it requires careful consideration of several factors and adherence to best practices. Here are steps to help you bend aluminum successfully without causing damage:
Techniques for Filling Curved Cavities
One critical aspect of successful aluminum bending is addressing the depression or “v-curve” that often occurs on the aluminum cavity profile during the process.
Filling the Curved Portion: The curved portion of the cavity can be a vulnerable point during aluminum bending. Effectively filling this area can help maintain the structural integrity of the material. The choice of filler and method depends on whether the cavity is open or closed.
- Filling Open Cavities – When dealing with open cavities, there are two primary methods for filling the curved portion:
Spring Steel Sheets: Open cavities can be effectively filled with spring steel sheets. These sheets provide support and prevent the aluminum from collapsing during bending. Spring steel sheets are pliable enough to follow the contours of the cavity while offering adequate resistance to deformation.
Teflon Filling: Teflon is another excellent choice for filling open cavities. Its low-friction properties make it ideal for reducing resistance during the bending process. Teflon acts as a lubricating layer between the aluminum and the tooling, facilitating smooth bending without excessive stress.
- Filling Closed Cavities – Closed cavities typically require a different approach for filling:
Sand Filling: Closed cavities are usually filled with sand. Sand serves as a consistent and uniform support system, preventing the aluminum from collapsing or cracking during bending. The sand filling process requires careful compaction to ensure even pressure distribution.
Wax Filling: In some cases, closed cavities can also be filled with wax. Wax provides support and even pressure while remaining pliable. This approach is particularly useful when you want to avoid abrasive substances like sand.
Workpiece Support – The Key to Precise Bending
When aluminum is bent, it comes with challenges such as warping and distortion. Properly supporting the workpiece during bending is a critical aspect of achieving successful and precise results.
The Significance of Workpiece Support
Workpiece support plays a pivotal role in metal bending processes. Without adequate support, the force applied during bending can cause the workpiece to warp or distort. Warping and distortion not only compromise the quality of the final product but also lead to increased material waste and production costs. Here’s why workpiece support is so crucial:
- Even Force Distribution: When the force during bending is not evenly distributed, stress concentrates at specific points on the workpiece. This can result in localized deformations or warping.
Proper support ensures that the force is uniformly spread across the workpiece, reducing the risk of these issues.
- Material Preservation: Workpiece support prevents over-straining of the material, which can lead to stretching, cracking, or other structural damage.
By distributing the force evenly, support helps maintain the structural integrity of the material.
- Precision and Consistency: In industries where precision is critical, such as aerospace or automotive, workpiece support is essential to maintain consistent product quality.
Support ensures that the workpiece retains its intended shape and dimensions throughout the bending process.
Four Ways to Properly Support the Workpiece
Proper workpiece support involves using the right tools and techniques to ensure even force distribution during bending. Here are some common methods to achieve this:
- V-Dies and Block Dies: V-dies and block die are tooling components designed to support and shape the workpiece during bending.
V-dies provide focused support for narrower sections of the workpiece, while block dies offer broader support for larger areas.
- Backgauges: Backgauges are adjustable stops that help position the workpiece accurately and hold it in place during bending.
They ensure that the workpiece remains parallel to the bending equipment, preventing unwanted shifts that can lead to distortion.
- Mandrels and Support Arms: In more complex bending operations, mandrels and support arms are used to provide additional support and help maintain the workpiece’s shape.
These tools are particularly useful when working with long or thin materials.
- Material-Specific Solutions: Depending on the material being bent, there are specific support solutions. For example, materials like aluminum may require special care to prevent scratching or marring during bending.
Material Preheating in Aluminum Bending
One solution that can greatly enhance the bending process is material preheating. The success of bending high-strength aluminum alloys, such as those from the 7000 series, often hinges on the temperature of the material. Preheating this type of aluminum to a specific temperature can significantly impact its ductility and ease of bending, resulting in several notable advantages.
- Enhanced Ductility: Preheating softens the aluminum, making it more ductile and less prone to cracking.
The material becomes more pliable, allowing it to undergo bending without resisting deformation.
- Reduced Risk of Cracking: High-strength aluminum alloys, while strong, are more susceptible to cracking during bending.
Preheating minimizes the risk of cracks by reducing the internal stress within the material.
- Improved Formability: Preheated aluminum is easier to shape, offering greater formability.
This enhanced formability allows for more precise and complex bends without the fear of damage.
- Controlled Bending: The softened aluminum can be manipulated more precisely, enabling controlled bending operations.
This is particularly important when achieving tight radii or intricate shapes.
Optimal Preheating Temperatures
The effectiveness of preheating aluminum hinges on reaching and maintaining the right temperature. The ideal preheating temperature varies depending on the specific alloy and thickness of the material. Here are some general preheating guidelines for common aluminum alloys:
- 7000 Series (e.g., 7075): Preheat to a range of 350°F to 450°F (175°C to 232°C) for optimal results. This temperature range offers excellent ductility while preserving material strength.
- 6000 Series (e.g., 6061): Preheating to a lower range of 250°F to 350°F (121°C to 175°C) can significantly enhance the formability of these alloys.
- 1000 Series (e.g., 1100): Lower-strength aluminum alloys may require preheating at temperatures closer to 200°F (93°C) to achieve improved ductility.
It’s important to note that the exact preheating temperature may vary based on the specific alloy’s composition and the thickness of the material being bent. Experimentation and consulting material specifications are often necessary to determine the optimal preheating conditions.
Top 7 Tips
Material Thickness: Thicker aluminum requires more force to bend and is more susceptible to cracking. Consider using thinner aluminum if the project allows for it, as it is generally easier to bend without breaking.
- Proper Tools and Dies: Use high-quality bending tools, including dies and punches, that are specifically designed for aluminum bending. Ensure that the tooling is clean and free from any defects that could transfer to the aluminum.
- Correct Bend Radius: Determine the appropriate bend radius for your application. Smaller bend radii require more force and may increase the risk of cracking. Choose a bend radius that suits the aluminum’s thickness and formability.
- Lubrication: Apply a suitable lubricant to the aluminum’s surface, which reduces friction and prevents galling or scoring during the bending process. Lubricants specifically designed for aluminum are recommended.
- Controlled Force and Speed: Apply force gradually and evenly during the bending process. Avoid sudden or excessive force, as it can lead to cracks. Slow and controlled bending with consistent pressure is key to success.
- Prevent Over-Bending: Over-bending can lead to defects or fractures when the material is released. Use backstops or mechanical stops to limit the degree of bending, ensuring that the aluminum doesn’t bend too far.
- Minimize Repeated Bends: Avoid multiple bends in the same location, especially with thicker aluminum, as it can weaken the material and increase the risk of cracking.
In this article, by considering these factors and best practices, you can effectively bend aluminum without breaking it and achieve the desired results in your bending projects, ensuring that the final products meet the desired specifications and standards.