Stainless steel tubing is a popular choice in industries that require high levels of corrosion resistance.
However, bending this tubing can be a challenging task that requires careful consideration of various factors, including the bending radius, ductility, and hardness of the material.
In this informative article, we explore the different techniques and precautions involved in bending stainless steel tubing, with a special focus on the 304 stainless steel round pipe.
Whether you’re a seasoned professional or a beginner in the field, this article provides valuable insights into the bending technology for stainless steel tubing.
From the hot and cold bending methods to the technical difficulties and precautions involved, we cover it all. So, if you’re looking to improve your knowledge and skills in bending stainless steel tubing, this article is a must-read.
With our expert guidance, you’ll be able to achieve smooth, accurate bends that are free of cracks and deformation, ensuring your products meet the highest standards of quality and durability.
What Should Be Paid Attention to When Bending Stainless Steel Tubing?
Industrial stainless steel tubing is widely used in various fluid drainage systems due to its good corrosion resistance, making it a popular choice in environments with high levels of corrosion.
However, when bending the stainless steel tubing for the use of corrosive liquids, it is important to consider the bending radius.
Bending the stainless steel tubing is a common processing form in the industry, but it is not as simple as it may seem. It requires careful study and experience, as different models of stainless steel tubing have different levels of ductility and hardness, with some being more prone to stretching and others to cracking.
1. Reduced ductility
In order to prevent cracking during bending, it may be necessary to use a larger bending radius when bending in the direction of the bend. When bending in the transverse direction, the reduced ductility can allow for a tighter internal bend without damaging the outer surface of the bend.
2. Local heating material
When bending thick materials, it may be necessary to preheat the material prior to bending to make the process easier and reduce the amount of force required.
3. Rebound treatment
The stainless steel tubing will experience springback when it is released from the bending force. The springback is the result of elastic strain release, which is directly related to the material’s yield strength. To achieve the desired bend angle, a larger angle may be required, especially for high yield strength stainless steel tubing.
The required angular clearance increases with the increase in radius, and with a large radius, the amount of springback may be significant. If the bent material is stiff, it may require heat treatment.
However, in some cases, the heat bending method may only achieve the desired bend angle and radius temporarily. Once the material cools, it may experience slight springback.
4. Thermoformed stainless steel tubing
Hot forming of stainless steel tubing eliminates strain hardening, cracking, and deformation and changes its molecular structure through high temperatures.
Compared to cold forming, it is easier to handle hot-formed stainless steel tubing with a bending machine. However, there are limitations to hot forming as heating the stainless steel tubing to near its melting point can cause it to break.
High temperature can also lead to surface oxidation and decarburization, which can cause various problems with the product. This method is generally used cautiously when bending stainless steel tubing.
5. Inner bending radius
For industrial stainless steel tubing, it is necessary to determine the value of the internal bending radius. The radius of longitudinal bending should be larger than that of transverse bending. The hardness and thickness of the stainless steel industrial tubing determine the required bending radius.
To determine the bending radius, there is a technique to subtract 50% from the material stretching ratio provided by the supplier.
Bending Process of 304 Stainless Steel Round Pipe
The 304 stainless steel round pipe is a hollow, round stainless steel pipe that is widely used in various building decoration applications such as fences, stair handrails, and courtyard doors.
The bending process must be smooth, accurate in terms of angle, and free of cracks.
Next, I will explain the bending technology for 304 stainless steel round pipes.
1. Bending method of round pipe
1. Hot bending method:
First, in preparation for bending the 304 stainless steel round pipe, secure the arc car’s rollers onto an iron plate based on the outer diameter of the pipe. Fill the pipe with sand and plug both of its ends with wooden plugs. Then, preheat the section of the pipe that is going to be bent with a flame.
2. Cold bending method:
Before using the pipe bending machine, it is important to thoroughly test the machine. To avoid cracking, there should be a gap equal to the thickness of the plate at the bottom and a bending notch with a depth of 8 times the thickness of the plate should be selected.
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2. Technical difficulties
1. During machining, the friction between the workpiece and the tool will generate high heat, and the tool is easy to wear.
Therefore, the requirements for tool materials are more strict, requiring wear resistance and high temperature resistance.
And must meet the requirements of sharp edges.
2. The bending process is slow and requires a large force, leading to low production efficiency.
In addition, due to the high heating capacity, sulfur chloride is generally used as a good cooling oil, and the effect is better.
Therefore, it is important for workers who process 304 stainless steel round pipes to have a good level of experience and technical skill.
3. Precautions
1. Bend:
The general requirements for 304 stainless steel round pipe bending radius (R) are that it should be at least 1.5 to 2 times the diameter.
If the bending radius (R) is too small, the bend will be flat.
The bending radius (R) of the same stainless steel pipe should be consistent in order to meet the consistency of the wheel die.
The straight edge length of the bend must be at least 2 times the diameter, otherwise the bend die cannot be clamped smoothly.
2. Process hole:
Process holes shall be reserved for 304 stainless steel round pipe welds to better discharge welding slag generated during welding.
3. Processing performance:
First, consider the machinability of 304 stainless steel round pipes.
Stainless steel has high plasticity, toughness, cutting energy consumption, cutting temperature, low thermal conductivity, poor heat dissipation, and can easily cause tool temperature rise.
These factors can affect the bonding and weldability of stainless steel and cause blockages during the cutting process, leading to a reduction in the surface finish of the stainless steel pipes.
