Stainless steel is one of the most commonly used materials in manufacturing. As a result, bending stainless steel tubing is a common forming process for producing metal parts for a variety of applications. Engineers and designers regard it as a critical operation for system piping and tubing. However, we need to master the correct metal bending process.
The increasing use of some high-end stainless steel materials makes their processing complex. Therefore, it is vital to understand how to bend steel tubing. In this article, we will introduce the most efficient way to bend steel tubes. In addition, we will help you get the most out of the process.
Table of Contents
Basics and Challenges of Bending Stainless Steel Tubing
Using steel for custom prototyping can be challenging. This is because it is a very hard metal material. However, it is a ductile and malleable material. It can be easily molded into various shapes using different processes. Metal Bending Process A process that helps in processing steel pipes into various useful shapes.
While it is possible to bend stainless steel into various shapes. However, this technique may require a lot of direct pressure from specialized tools. When it comes to bending stainless steel materials, the focus shifts to the higher difficulty of bending. This difficulty usually depends on the thickness of the pipe.
Thick-walled tubing usually requires more pressure to bend. In addition, the size and shape of certain tubes may require the use of specialized bending equipment. In addition, the risk of springback is a considerable problem when bending stainless steel tubing.
How to Bend Stainless Steel Tube
Stainless steel tubing is difficult to work with. However, some methods can help simplify the process. This section describes how to bend stainless steel tubing using the most efficient method.
Mandrel Tube Bending
Rotary draw tube bending machines are usually used for mandrel bending of metal tubes. A mandrel is a tool used to maintain the shape of the tube during the bending process. The mandrel may include additional spherical steel to ensure that it remains within the bent section during the bending process.
The setup for mandrel tube bending includes:
Pressure Die: The pressure die holds the tangential or straight portion of the steel tube.
Clamping Die: The clamping die rotates the steel tube around the bending die.
A Mandrel: The mandrel supports the inside of the steel tube in the bend and may include some articulating balls.
Scraper Die: The scraper die makes contact with the tube prior to the tangent point of the inside radius. It wipes the workpiece to prevent wrinkles on the inside radius.
Mandrel tube bending dominates the stainless steel tube bending process. This is especially true in applications where smaller radii are required. When deciding how to radius bend stainless steel tubing, the mandrel tube bending process should be used. This method provides the best control of ovality and wall thinning.
The use of a mandrel at the inside diameter (ID) helps support material flow during bending. Similarly, the compression mold supports the outside diameter (OD). These components work together to keep the OD and ID of the tube consistent during metal bending operations. Mandrel tube bending helps prevent the most common bending problems, especially spring back. In addition, it prevents creasing, flattening, and kinking.
Three-roll rollers
Roll bending or angle bending is a good method for larger workpieces. It usually consists of three rolls arranged in a pyramid shape. In addition, depending on the size of the cross-section, vertical or horizontal milling direction can be used. The rollers can be moved to form a large, defined radius.
The machine decides which rollers move to which side. The radius of the pipe or tube is determined by the position of the central roll. Some machines have a top roll that moves up and down to get the correct angle. On some machines, the bottom two rolls move while the top roll remains stationary.
Manufacturers often use roll bending to create spirals. The operator can raise the tube after each revolution, thus creating a continuous coil. In this case, the workpiece should have a large radius spaced one diameter apart. However, if the coils are widely spaced, an additional roller is required. This roller helps to guide the tube outwards during coil formation.
Rotary Draw Bending
This method is similar to the mandrel tube bending process but without the mandrel. It improves the accuracy of the tubing components and allows for complex blends without distortion. This metal bending process usually uses a fixture to support the machine.
The fixture pulls the tube into a shape equal to the radius of the tube. With this technique, draw bending allows the tube to be bent into an acute angle shape. In addition, excellent accuracy and consistency can be maintained.
Rotary draw bending is a common process used by manufacturers for tubular parts in structural frames and machinery. Examples include roll cages, bicycle handles, and handrails.
Compression Bending
Compression bending is an effective method of bending stainless steel tubing. This method uses a compression die to bend the material around a fixed bending die. The system first clamps the tubing behind the back cut point. The compression die then helps “compress” the workpiece onto the bending die.
Compression bending works best on symmetrical workpieces. These tubes have similar bends on both sides. These tubes can be bent in a single setup using a machine with two bending heads. Therefore, you may choose to use this method when the roundness of the curve is not the most important factor.
When it is desirable to increase production while reducing costs. Compression bending is good for speed and economy. However, we do not recommend this method for tubing with a centerline radius (CLR) less than twice the bend diameter. That is, a 1-inch bend requires a minimum of 2 inches of centerline for proper bend quality.
Do you need another type of metal bending process ? If you need to bend stainless steel pipe, Yonglihao Machinery can provide you with quality metal bending services. Contact us to get a quote today.
Considerations for Bending Stainless Steel Tubing
There are a number of structural issues and aspects that you must consider when deciding how to bend steel tubing. The most important of these are listed below:
Bending Radius
Steel tube bending often requires a smaller radius. In most cases, the thinning of the outer wall of the bent tube will result in deformation of the bent tube. This can be avoided by using a mandrel as a support. This shows that the mandrel bending process is the most reliable option in this particular case.
Sometimes, obtaining a smaller radius causes the steel to exceed its elastic limit. This usually leads to deformations such as creases and humps. In such cases, three-roll bending or rotary draw bending is the preferred option.
In addition, smaller bending radii often require more precise force application. Depending on the inner diameter and thickness of the tube, 180-degree bends can be achieved. However, a larger “U” shape may be required to maintain structural integrity and internal shape.
Yield Strength
Yield strength is another important factor to consider when bending stainless steel tubing. Yield strength is one of the properties of steel that increases the likelihood of spring back. Materials with higher yield strengths have higher elastic strain ratios. Such materials will also exhibit greater springback compared to materials with lower yield strengths.
Therefore, before bending a steel, its yield strength must first be calculated. Each bending produces an appropriate strain. Therefore, the yield strength should be checked against the exact amount of strain expected.
Material Thickness
Variations in material thickness are an important issue when bending stainless steel tubing. Thickness variations can have a considerable effect when manufacturers are striving to achieve precise bending tolerances. It is common to discuss the thickness of various stainless steels in terms of average values. However, the actual material thickness is actually within a specific range.
As a result, even small thickness variations can have a dramatic effect on the bending angle. This can have a significant impact on performance, especially if tight tolerances are required. It is important to realize that certain materials may require greater bending forces than others during the production of custom tubing. Thicker stainless steel requires greater bending forces than thinner stainless steel.
Bending a thicker material within a specified radius will create more strain than bending a thinner material. The thicker the wall of the tube, the more pressure it can withstand. Likewise, the thinner the pipe wall, the more likely it is to collapse during bending.
It is therefore recommended to set the bending power correctly to avoid inconsistencies and material deformation. This means that you must choose the right process and configure the machine correctly.
Welded and Seamless Steel Tubes
Both seamless and welded steel tubes can be bent. However, seamless steel tubes bend better when the required radius is small. Welded pipe, on the other hand, has a thinner wall and is therefore more suitable for larger-diameter applications. Seams in the welded pipe may affect the consistency of the bend. This is due to the fact that stress concentration points are created on the pipe.
Due to stress concentrations, the working pressure of welded tubes is 20% lower than that of seamless tubes. In addition, we must consider the possibility of weld seam formation errors. This would result in the tube not being accurately rounded. This would prevent proper bending of the welded steel pipe.
Stainless Steel Pipe Bending Radius
The bend radius of a steel pipe is the radius measured from its centerline. Bend radius tools usually vary from bender to bender. However, the most commonly used tube benders follow precise rules of thumb.
|
Bend Angle
|
1/8 (9/16)
|
1/4 (9/16)
|
3/4 (3/4)
|
5/16 (15/16)
|
3/8 (15/16)
|
1/2 (1 1/2)
|
|---|---|---|---|---|---|---|
|
30°
|
0
|
0
|
0
|
0
|
0
|
1/16
|
|
45°
|
1/16
|
1/16
|
1/16
|
1/16
|
1/16
|
1/16
|
|
50°
|
1/16
|
1/16
|
1/16
|
1/16
|
1/16
|
1/8
|
|
55°
|
1/16
|
1/16
|
1/16
|
1/8
|
1/8
|
1/8
|
|
60°
|
1/16
|
1/8
|
1/16
|
1/8
|
1/8
|
3/16
|
|
65°
|
1/8
|
1/8
|
1/8
|
3/16
|
1/8
|
1/4
|
|
70°
|
1/8
|
1/8
|
1/8
|
3/16
|
3/16
|
5/16
|
|
75°
|
1/8
|
3/16
|
3/16
|
1/4
|
1/4
|
3/8
|
|
80°
|
3/16
|
3/16
|
3/16
|
5/16
|
5/16
|
7/16
|
|
85°
|
1/4
|
1/4
|
1/4
|
3/8
|
3/8
|
9/16
|
|
90°
|
1/4
|
5/16
|
5/16
|
7/16
|
7/16
|
11/16
|
The standard tensile bending radius is 2 x D
This indicates that a tube with a diameter of 20 mm requires a bend radius of 40 mm. Smaller bend radii (½ x D) are conceivable. However, bend radii smaller than 2 x D are usually more costly.
Minimum bending radius of 7 x D
Material properties and wall thickness affect the minimum bending radius. Therefore, it is technically safe to comply with the 7 x D standard. It is also recommended to provide larger tolerances on the bending radius.
Application of Stainless Steel Tubes
Due to its ease of assembly, stainless steel tubing is used in a wide variety of applications. It can also withstand harsh environments such as high temperatures and pressures. This is one of the qualities that make stainless steel valuable in certain fields.
For example, in the automotive industry, CNC machines can use stainless steel tubes to produce high-quality mufflers. This is because they can withstand the high pressures that pass through them.
In addition, stainless steel is used in medical devices, solar panel frames, industrial machinery and electrical wiring. Steel tubes can be made in a variety of shapes and thicknesses, making them even more useful.
Stainless steel tubes are used in a variety of household appliances, heating, water supply, and plumbing systems. This versatile material can be used in almost all industries. This includes aerospace, automotive, technology, electrical, construction, food and beverage, and more.
Summary
As mentioned earlier, steel tubing is suitable for a variety of industries and applications. In addition, the advent of advanced machines and modern methods has improved the precision of steel tube bending. Therefore, choosing the right materials, techniques and equipment will increase your chances of getting the ideal bent steel tube.
If you want to learn about more cost-effective methods and get the right guidance for bending stainless steel, contact us. Yonglihao Machinery’s CNC machining and metal bending services will be ideal for you!
In addition, we offer customized steel tube processing and fabrication services that you won’t find anywhere else. Our skilled team offers rapid prototyping services at competitive prices. Not only that, but our professional staff can provide expert guidance on your design. We will then assist you in producing the ideal steel tube of the highest quality.
Frequently Asked Questions
How Difficult is it to Bend Stainless Steel Tubes?
Due to the hardness of the material, bending steel tubes can be quite difficult. However, choosing the right fabricator and being well-informed about the procedures and tools. Then the whole process can be made smoother.
Is Mandrel Steel Tube Bending Better Than Roll Bending?
Which method to use depends on your bending requirements. Mandrel bending is suitable for smaller radius bending operations to prevent flattening, creasing, and kinking. Roll bending, on the other hand, is best suited for finer tubes with larger radii.
What Are the Application Areas for Stainless Steel Tubes?
Many companies use stainless steel tubes for a variety of purposes. They are used in a wide range of applications, including household appliances, automotive and aircraft components, electronics, piping systems, medical devices, and more.