How can you bend aluminum without breaking it? The 8 best measures (2023)

Aluminum foil easily breaks after bending or cracks after bending with anodizing. Many aluminum alloy processing companies are confused about this. So how do you bend aluminum without breaking it? 8 main reasons and preventive measures why aluminum breaks after bending.

3 Factors Affecting Aluminum Alloy Bending

One of aluminum's most useful properties is its malleability, and one way to shape metal into the desired shape is to bend it. noAluminiumAlloys and tempers lend themselves better to bending than others. Here's what you need to know to choose the right one for you.

What points can help you identify the right league to retire? And which alloys are better for bending?

Formability, thickness and radius of curvature and percent elongation.

malleability

In general, higher strength means that the aluminum alloy is more difficult to bend due to the trade-off between strength and elongation - ductility. When one increases, the other decreases.

Formability is the ability of a given material to deform permanently without being broken or torn by the forming process. Permanent deformation is also known as plastic deformation in the materials science world.

Formability is generally a relative term and not a specific value. For example, the applied force required to form a product depends on more than just a material's strength and ductility. It also depends on factors such as the shape of the part and the thickness of the starting material.

In other words, we can measure the resistance to deformation to produce a specific part from a specific base material. However, changing the shape of the part or the physical properties of the starting material changes the force that must be applied.

That being said, there are standardized tests such as ASTM E2218: Standard Test Method for Determining Formation Limit Curves. We can use these tests to establish a formability "classification" for various alloy sheets. We can use them to find out which alloys have the best basic formability.

thickness and radius of curvature

AluminiumAlloys work their way through and become stronger during the bending process. Therefore, the thickness and radius of curvature are factors that you need to consider.

If you've worked with regular aluminum foil, you know that it folds easily. However, if you were to fold aluminum foil a thousand times thicker than aluminum foil, it would be much more difficult! Because the thicker a material is, the more difficult it is to bend.

You can also bend an aluminum gutter with your own hands. But if you try to bend it at a sharp angle without breaking it, you're in trouble! Bending metal to a small radius of curvature can cause it to break or crack.

The manufacturer offers certain keys.Table MountainsmiGeneral ruleswhich are useful for understanding the bending limits for specific aluminum alloys. You can use them to determine the minimum allowable bend radius for specific aluminum sheet thicknesses.

percentage elongation

Studying percent elongation and the difference between yield point and tensile strength will also help you make the right choice. When comparing alloys and tempers, one should look to those with the widest range between yield strength and tensile strength, as this indicates better formability.

Percent elongation represents the material's ability to plastically deform under load. It is also known as plastic deformation or staining applied beyond a material's elastic limit.

The more ductile aluminum alloys can experience more plastic deformation with small increases in applied stress. This results in better overall bendability of the aluminum.

Like the other properties, the percent elongation varies for each alloy. Take a lookthe stress-strain curve above🇧🇷 You will see that tempered aluminum alloy 3003 (shown as AA3003-O) has a very high percent elongation (% stress) of around 35%. Compared to other alloys, it has a very high bending capacity.

Which aluminum alloy is best for bending?

The best series to form and therefore bend are the alloy series 3xxx, 5xxx and in some cases 6xxx. For example, aluminum alloy 6063 is a good choice, while 6082 is harder.

Numerous metal alloying agents can be combined with aluminum to produce various aluminum alloys. The naming system uses four digits, with the first digit representing their chemical composition.

In general, 1XXX, 3XXX and 5XXX series aluminum alloys show better bendability than other aluminum alloys. Some 6XXX series alloys are also quite flexible.

However, the different qualities that each offers can make some more desirable than others. For example, 1XXX series aluminum generally has poor mechanical properties and is not suitable for structural applications.

The best series to form and therefore bend are the alloy series 3xxx, 5xxx and in some cases 6xxx. For example, aluminum alloy 6063 is a good choice, while 6082 is harder. I would avoid using alloys from the 2xxx and 7xxx families as they are very strong and therefore difficult to form. With the right hardness, however, it is also possible to bend these alloys.

Aluminum alloy 3003

In most cases this is probably the best alloy for bending. It achieves medium strength, very good cold formability and high elongation. It also offers one of the largest differences between yield strength and tensile strength.

Alloyed primarily with manganese, this alloy is one of the most commonly used aluminum alloys for bending applications. It has excellent formability properties and requires no heat to bend or form.

Companies typically make gutters, roofs, siding, chemical equipment, and storage tanks from 3003 aluminum.

Aluminum alloy 5052

This league comes right behind. You get high elongation (though not as high as 3003) and a solid difference between yield and tensile strength. You also get high strength compared to other non-heat treatable grades and excellent corrosion resistance. After annealing, it outperforms 3003 alloys in formability.

With magnesium as the primary alloying element, AA5052 exhibits medium to high strength properties. At the same time, it maintains good bending capacity and designers can use it for more intense applications than AA3003. The corrosion resistance of this alloy is also excellent in seawater, which means that it is excellent for marine equipment applications.

Manufacturers typically produce hydraulic hoses, traffic signs and hardware, medical equipment, marine equipment, and electronics (chassis and cabinets).

Aluminum alloy 5083

Not far behind 5052 is its big brother and a classic marine alloy with good corrosion resistance and weldability. There are some variations in terms of temperament, but if you choose H111, H112 or O temperament, everything is fine.

Aluminum alloys 6061 and 6082

They are versatile heat treatable alloys that offer a satisfactory difference between yield and tensile strength and good elongation after annealing. However, your ability to flex decreases as you move to T4 and T6 temperaments. So my recommendation is to double the T4 condition and then heat treat to T6 if possible.

Don't forget that the granularity of the material also affects bendability, although granularity affects many processes, not just bending.

Alloy 6061 is widely known as "structural aluminum" due to its common use in structural (construction) applications. However, due to its excellent properties, it is also used in food and beverage containers, ladders, airplane and car parts, scuba tanks, bicycle frames and much more.

Why are these 4 leagues important?

Despite their different properties, these alloys are excellent examples of the flexibility of aluminum alloys. They show that although some aluminum alloys exhibit better formability and percent elongation for a given bend radius and thickness, each has a unique purpose and a variety of applications.

Although slightly less bendable, the strength of alloy 6061 makes it one of the most widely used aluminum alloys. Additionally, Alloy 3003 has multiple uses in applications that require superior bendability. Meanwhile, Alloy 5052 is widely used due to its balance of bendability and strength.

Consider the tempers in the alloy's bendability.

Be careful with tempers when trying to optimize the bendability of aluminum alloys. Temperament is just as important as garters.

For non-heat treatable 3xxx and 5xxx alloys, the O temper is the easiest to bend.

Hardenable alloys 6xxx, 7xxx and 2xxx should preferably be bent in the T4 temper as they have a lower yield strength. However, there is a downside. The yield strength in the T4 temper varies over time due to natural aging, a slow hardening process that occurs over time.

Although the yield point variation is small for a short period of time, it can cause elastic recovery variation in some bending processes. So, in some cases, doubling T6 might be a better option. There are also special heat treatments that stop natural aging and allow the material to be heat treated to T6 after bending, which can be considered.

T4 temper is a medium to low yield strength bending, however some bending processes can cause fluctuations in the spring

The T6 temperament is the hardest to bend, but there is no spring variation

Aluminum foil easily breaks after bending or cracks after bending with anodizing. Many aluminum alloy processing companies are confused about this. So how do you bend aluminum without breaking it? 8 main reasons and preventive measures why aluminum breaks after bending.

8 main reasons and preventive measures for aluminum breakage after bending

1. Thickness:Very thick aluminum plate, not easy to bend. Everyone knows how to use the thinnest possible aluminum foil.
2. Tenacity:The aluminum plate is very hard and breaks easily. The choice of aluminum foil mainly depends on the quality and condition of the aluminum. Usually T1, T3 and T5 are used. The T6 and T7 series are very hard and must be annealed to hardness 0 before bending.
3. textured direction:The bending direction must be perpendicular to the direction of the aluminum plate structure and not parallel. For aluminum sheet parts that require stretching, it is better to machine them after bending if processing allows, otherwise the possibility of flex fracture increases.
4. Biegewinkel R:The larger the angle R, the higher the success rate, so try to increase the bend angle R as much as possible.
5. Cracks after bending aluminum profiles are caused by high tensile strength and unfulfilled laying stress. The edge of the aluminum profile is absent, resulting in creases. This can be solved by improving the cross-sectional area of ​​the profile or adjusting the tension.
6. The depression of the curved surface occurs mainly in the profile of the aluminum cavity. Before stretching and bending this material, it is necessary to fill the curved part of the cavity with putty. Open cavities can be stacked with spring steel sheets or filled with Teflon, while closed cavities are often filled with sand.
7. Correctly adjust the mold gap according to the position generated by the vertical marks on the side, and improve the mold material, which can effectively prevent the aluminum profile surface from being scratched.

Aluminum bending tips

Pay attention to the grade

With aluminum, the harder the grade, the more reclamation you have to deal with; Very soft aluminum may not spring back.

Look for wrinkles along the fold line

Aluminum generally loses its integrity when the material is wrinkled. If you make aircraft parts with this fold along the fold line, the parts themselves become unacceptable.

Inner bend radius

When bending aluminum, remember that the smaller the inside radius of the bend, the greater the chance that the part will break. Also note that for best results and fewer tears on the outside of the fold, the fold line should cross the grain of the material or run diagonally whenever possible.

Ideally, part designers should know that 3003 and 5052 will flex for aluminum grades, and 6061 will not. This is of course a generalization as there are ways to shape 6061. Aluminum series bendability tends to decrease as you go up the hardness list, from annealed to T4 and T6. Bending these hardened alloys is not impossible, but it is very difficult and will likely require large bend radii to avoid cracking on the outside of the bend. If you're not careful, you can completely break the fold line.

Continue reading:How to choose the methods of forming and bending aluminum?

Bending and forming aluminum extrusions involves considering factors such as inside and outside diameters, critical surface areas and mechanical strength, which can affect the final fit and finish of a part. Different types of bending and stretching processes produce different results.

3 factors to consider when bending aluminum profiles

Aluminum can be extruded and bent to specified tolerances or standard dimensional tolerances. While a product's dimensions and bend angles can be measured and measured methodically, the end product is only as accurate as the equipment or bending method used. Deformation of the inside or outside radii can be a design issue and can also dictate which forming process to use to bend or shape the aluminum profile.

Therefore, several factors 3 must be considered when selecting the bending process that is appropriate for a particular product.

1. What tolerances or deviations are to be expected for the inner radius, outer radius and overall length of the part?
2. Which surface areas are decisive for the appearance?
3. What is the required mechanical strength?

5 common bending and forming processes for aluminum profiles

Each of the 5 folding methods below has a number of advantages. Successful design and determining the best method ultimately depends on the desired tolerance, appearance and strength of a final product.

Methods of bending and shaping 1#:Lunge Flex or Thrust

1. Definition:Compression or ram bending, as the name suggests, uses a ram to force the extruded metal part into a bending tool.
2. Working principle:A die pushes the extrudate into the compression dies and forces the extrudate into the desired folded shape.
3. Features:With programmable bend angles, this form of bending allows bending close to multiple planes, although only one radius can be bent at a time. Ram bending offers inexpensive tooling and good bend accuracy at a low cost per bend.
4. Inscription:Ram or push bending is ideal for components such as boat barrels, portable frame supports, wheelchair frames and medical beds.

2# Forming and Bending Methods:Hydraulic folding by rotary stretching

1. Definition and functional principle:In the hydraulic rotary bending process, manufacturers place extruded aluminum in a bending machine and hold it in place with a stationary or sliding pressure die and clamping block. The hydraulically driven round bending tool is rotated by up to 90 degrees and bends the extrudate during rotation.
2. Features:
   • With the hydraulic round bending process, a profile can only be bent by one radius at a time.
   • The incorporation of a mandrel or other tooling component to hold the rotating mold can prevent the product from wrinkling or warping, although its use is not mandatory.
   • Single-axis controlled rotation can be bent to within a tenth of a degree for extremely precise bend angles.
3. Inscription:Hydraulic bending is commonly used to form round tubing or tubing for applications such as handrails and is ideal for large diameter extrusions such as building signage.

Bending and forming process 3#: Electric rotary bending

1. Definition and functional principle:Electric rotary bending uses the same process as hydraulic but allows for faster setup.
2. Features:
   • Bends are also more accurate and repeatable because angles and twists can be automated in a machine's programmable logic controller.
   • Extruded aluminum rotations can also be machined into flat variable curves.
3. Inscription:The rotary electric drive method is best suited for applications that require multiple curves per part side-by-side or curves with different radii for each part.

4# Forming and Bending Methods:Three roll fold

1. Definition:Three-roller bending pushes an extruded profile around three different rollers arranged in a triangular shape.
2. Working principle:The rollers adjust to form a precise angle with up to 360 degree rotation that can roll horizontally or vertically. As the motorized rollers slowly move the extrusion, it begins to bend and flex.
3. Features:
   • Extrusions are limited to one bend per cycle, meaning a larger bend angle would take longer to achieve the desired angle.
   • Although it may take longer, the maximum bend radius is unlimited.
4. Inscription:Symmetrical profiles are preferred for roll bending.

5# Forming and Bending Methods:stretch training

1. Definition and functional principle:In stretch forming, a strand is laid along a stationary round layer die and clamped at both ends. The machine begins rotating the clamped ends down at angles of up to 180 degrees, and the extrusion is bent around the die to achieve the desired shape.
2. Features:
   • The radius of curvature is unlimited with this method.
   • A stretch forming machine can simultaneously bend, rotate and lift an extrusion to create specific and unique shapes and angles for parts up to 25 feet long.
   • This method also provides the most precise and consistent flex through stretch control.
   • Due to the way the fixed curvature round die presses the extrudate, stretch forming has the least surface distortion and wear marks on the extruded part.
3. Inscription:Stretch forming is commonly used for parts with a larger radius of curvature, as the minimum radius of curvature is typically two to three times larger than other forming/bending processes.

For more information, see: The Definitive Guide to the Stretch Forming Process