Sheet metal bending involves using machines and tools to form metal into a specific shape.
This can be achieved using a press brake, punching machine, ironworker, or other machinery.
These machines utilize a power system to drive the tooling and apply pressure on the metal sheet, causing it to deform.
To ensure accurate results in sheet metal bending, several parameters must be determined before the process begins.
These parameters include the material thickness, bending radius, bending allowance, bending deduction, K factor, and others.
It is important to keep in mind that different materials have varying properties such as tensile strength and ductility.
Different machines may use different bending methods to produce the same profile from a metal sheet.
Therefore, it’s crucial to choose the suitable machine and approach based on the specific requirements and parameters of the project.
What Are the Methods of Sheet Metal Bending?
The sheet metal bending process results in different bending shapes based on the angle and radius of the bend.
To ensure precision in the bending process, standard bending methods are employed. These methods vary, but they all aim to produce uniform standards in the final profiles.
Let’s look at some of the main bending methods in sheet metal bending:
V-Bending – This is the most common bending process and is named so because of the V-shaped punch and die used in the process. The punch presses the metal sheet into the lower die, resulting in a V-shaped workpiece.
Roll Bending – This process is used for bending workpieces with large curls and involves the use of three rolls driven by a hydraulic system to bend the sheet.
U-Bending – This method involves using a U-shaped die to bend the workpiece. The punch is powered by a system to press the metal sheet into the U-shaped die, resulting in U-shaped profiles.
Rotary Bending – This method can bend the workpiece with a degree of more than 90. The final profile is like a V-bend, but the profile surface is smoother.
Edge Bending – This method is used in panel bending and involves the use of upper and lower molds that move up and down for bending. It’s usually used for shorter metal sheets to reduce sharpness and prevent damage to the bending edge.
Wipe Bending – This method is like edge bending. The metal sheet is placed on the lower die and pressure is applied to the protruding metal by a pressure pad and punch, resulting in bending.”
What Materials Are Fit for Sheet Metal Bending?
The choice of bending material is essential to achieve the desired bending result.
Some materials may be unsuitable for bending and may cause the tool to break or be damaged. Materials with low ductility can be heated to reduce the risk of breakage.
When selecting bending materials it is important to consider their properties.
The following are some of the materials commonly used in sheet metal bending and their properties:
Carbon steel: This material is strong, flexible, and ductile and is a recyclable and environmentally friendly option.
Mild steel: Mild steel has excellent flexibility and can be bent smoothly without heating.
Stainless steel: This material is strong, corrosion resistant, and has high tensile and yield strengths, making it a popular choice for bending processes.
Titanium: Titanium has high tensile strength, but can easily damage tools if not used properly. When bending titanium, it is necessary to increase the internal bend radius to prevent breakage and over-bend the material to achieve the desired shape.
Aluminum: Aluminium breaks easily when bent, so it is important to anneal it to prevent breakage. When bending aluminium it is important to avoid over-bending to reduce the risk of rupture.
Copper: Copper has high ductility making it an excellent choice for bending and is cost-effective. It is widely used in the sheet metal working industry.
Stainless Steel Sheet Bending
Characteristics of stainless steel
Steel is a combination of materials that contain small amounts of carbon, manganese, silicon, copper, phosphorus, sulfur and oxygen.
It is classified according to its carbon content as high-carbon, medium-carbon, low-carbon, and ultra-low-carbon steel.
Steel can be easily bent as the tools used to bend steel sheets are also made of steel.
However, bending stainless steel requires relatively large forces due to its high yield strength, hardness, and poor ductility.
In addition, stainless steel has a large spring back after bending, so a large bending radius is required to avoid breakage of the workpiece.
Bending stainless steel sheet precautions
Plate thickness and bending tonnage Before bending stainless steel, the thickness of the plate must be determined. Thicker plates require a larger bending machine.
Bending angle and bending radius
Bending angle and radius are key considerations.
A larger bending radius may result in excessive spring-back, while a smaller radius may result in rupture.
In general, the bending radius is around 0.2, for materials such as high-carbon steel, a larger inner radius is required to prevent rupture.
Stainless steel has a high spring back and the bending angle and radius should not be too small.
Bending jumping gazelle
The spring back of sheet metal is directly proportional to the yield strength of the material and inversely proportional to its modulus of elasticity.
Low-carbon steels have a low spring back and are ideal for high-precision workpieces, while high-carbon steels and stainless steels have a significant spring back.
The larger the bending radius, the greater the spring back.
Smaller bending radii result in higher accuracy.
Calculating the Bending Allowance
The bending allowance, which is the expansion of the outer side of the sheet, can be calculated with the knowledge of the sheet thickness, bending angle, and inner radius.
This calculation determines the required length of the sheet for bending.
The formula for calculating the bending allowance is BA=(π/180) x B x (IR+K x MT), or use a bending allowance gauge.
Bending with Machines
Finally, a machine like a press brake can be used for bending processing.
If the metal sheet is prone to cracking, it can be hot-formed or annealed.
Annealing improves the ductility of metals by softening them, and hot bending involves heating the metal to a red state and then bending it.
This blog post provides an overview of the basics of sheet metal bending, with a focus on important considerations for bending stainless steel.
Metal bending can be achieved using various machines, including press brakes. For simple bending tasks, a vise can also be used.
Learn more about shearing machines, bending machines, and other sheet metal equipment. For the best price, please contact us.