What Is Steel CNC Bending? Ultimate Guide

Steel CNC bending is a metal forming process that utilizes computer-guided machinery to precisely shape steel into desired angles and curves. Unlike traditional manual bending, CNC technology automates the process, allowing for greater accuracy, repeatability, and efficiency. The technology is particularly effective for producing complex shapes, high-volume parts, or components requiring precise specifications.

What is CNC Bending?

CNC (computer numerical control) bending is a fast, efficient, and cost-effective method of bending sheet metal components into virtually any desired shape or size using special computer software programming.

The process offers unparalleled flexibility in shaping materials like stainless steel, carbon steel, brass, and aluminum at unprecedented speeds with maximum accuracy and repeatability.

How to Understand Steel CNC Bending

Computer numerically controlled (CNC) bending for steel is a precise manufacturing technique performed using CNC press brakes, also known as CNC brake presses. These machines are capable of bending sheet metal, from very small pieces just a few millimeters in size to larger sections several meters long, depending on the size and capacity of the equipment. CNC press brakes come in two main types: down forming and up forming. In down forming, the machine has a fixed bottom bed with V-block tooling, while the top beam, equipped with V-blade tools, moves downward to create the bend. In contrast, up forming machines have a fixed top beam and a moving bottom bed. Despite these differences, both methods achieve the same result, allowing for any component design without restrictions.

CNC press brakes are programmed to handle the sheet metal blank at specific positions, as defined by the programmable back stop, to establish the bending points. The bend angle is controlled by how deeply the programmable V-blade penetrates the V-block—the deeper the insertion, the sharper the final bend. This level of control enables the creation of components with various bend lengths and angles.

The maximum bend length is determined by the CNC press brake bed’s length, while the thickness of the material that can be processed depends on the material’s tensile strength and the machine’s tonnage capacity. A larger V-block opening allows for bending thicker materials using the same tonnage, but it also results in a larger internal radius on the final product.

1. CNC bending machines are fully automated.

CNC machines automate the bending process by using a computer to control the machinery and hydraulic system to shape the component. This way, the components are shaped with more consistent bends and exact dimensions. 

2. CNC bending machines have a wide range of applications. 

CNC machines can handle sheet metal and tubes ranging from a few millimeters to multiple meters long. Additionally, they are fully capable of producing complex components due to the high-level technology that allows the machinery to run. 

3. Pairing the right metal size to the right machine is crucial.

One of the very few restrictions in the CNC bending process is the size of the machine and tensile strength of the metal. This can cause overbending and breakage of the component if the wrong machine is matched with an incompatible metal. 

How to Use a Steel CNC Bending Machine Correctly?

CNC Bending Machine for Angle Forming

A CNC bending machine for angle forming enables precise bending without the need for reference points. It uses two rotating bending bolts that communicate with the computer to determine the necessary final stroke. This system adjusts for spring back, achieving a high angle accuracy of +/- 0.2° immediately after the initial workpiece is loaded, significantly reducing material waste compared to manual adjustments.

This CNC angle-forming machine boasts multiple features, including its capability to bend aluminum in various orientations. Equipped with up to fifteen independent servo axes, operators have three-dimensional control over the bending process. Additionally, the machine allows for roll position adjustments to minimize any unbent flat sections. The BIT angle roller can be used to configure the machine for smaller workpieces, minimizing material waste.

CNC Bending Machine for Imprint Bending

A CNC bending machine for imprint bending is versatile and ideal for many applications. It offers all the advantages of CNC technology, featuring a modern color touchscreen display and two-axis control. The user interface is intuitive, allowing for easy programming and the storage of up to 200 different bend programs, which can be switched seamlessly. Stroke adjustments can be fine-tuned in increments of +/- 0.1°, and the machine can be operated through a foot switch or a dedicated manual control cable. Both automatic and jog modes are available for operation.

The machine’s software supports bend programming with a drag-and-drop interface, ensuring accuracy by scanning part ID codes. Graphical tool mapping provides a clear view of tooling locations, facilitating accurate program selection. LED indicators on the upper ram assist in precise tooling alignment. Additionally, the machine can be fitted with spiral bending tools, particularly useful for heat exchanger production.

Back Gauge Adjustment in CNC Bending Machines

In CNC bending, back gauge adjustment is crucial for accurate material handling. The bend line is defined at the punch’s nose, with half of the material’s elongation distributed to each side of the center. The back gauge position is determined through specific calculations, requiring it to be set from the die’s front face—half of the die’s body width away.

This adjustment helps position the sheet during the bending process. A button on the front control panel calculates the adjustment value, which is further detailed in a conversion table. Most CNC bending machines come equipped with both a hand wheel for fine adjustments and an electric quick-adjustment lever for the back gauge.

Stroke Adjustment in CNC Bending Machines

To adjust the stroke, a CNC bending machine needs an active oil pump. After starting the machine, adjust the stroke and align the plates with the bottom mold, ensuring sufficient clearance for the upper die to prevent mold damage. Stroke adjustments can be done manually or through electric quick settings.

When adjusting, it’s essential to consider the machine’s open and closed heights—representing the distance between the upper and lower beams when fully opened and fully closed, respectively. When altering the opening, ensure that materials won’t contact the variable die. For safety, avoid standing behind the CNC bending machine during operation.

CNC Bending Machine for Bending Prisms with Electronic Angle Measurement

A CNC bending machine designed for prisms features precise electronic angle measurement and dual flattened bending bars. It delivers an impressive accuracy of +/- 0.1°, making it ideal for small batch production and single-piece tasks. During bending, the tool rotates, allowing the operator to set the final stroke accurately. This system includes an impact feature, enabling users to specify the rotation angle for stroke calculations.

The production of glass prisms begins with a raw glass block or “blank” that undergoes grinding with a diamond-bonded metal wheel. This step removes most of the glass quickly, resulting in flat but rough surfaces. Once the prism shape is nearly complete, fine grinding eliminates scratches and subsurface imperfections, leaving the glass surface with a cloudy finish.

Are you looking for a way to bend metal with greater precision and control?

CNC bending machines offer one of the best solutions. This blog post provides an in-depth guide to understanding, operating, maintaining, and caring for CNC Bending Machines.

What Are the Benefits of CNC Bending for Steel

In manufacturing, time is money. When components are not produced to the highest standard, they are not usable, which means more material needs to be used and deadlines get pushed out.

With a Steel CNC bending process, the benefits OEM suppliers gain can be passed down to customers. These benefits include:

Cost Reduction

Because the CNC bending process is automated, it is one of the most efficient services compared to manual services, such as welding:

• Each process requires only one machine, not several steps across multiple machines.
• Automation makes it so that fewer laborers are needed in the production process.
• The laborer’s primary function in this process is to feed the machine the metal sheet or tube, cutting down on human error and inaccurate components.

Besides the initial investment costs, maintaining a CNC machine does not require a significant amount of capital. Cutting down on the number of laborers means a lower cost of labor. 

Time Saved

One of the greatest benefits of any automated machine in manufacturing is the amount of time saved in the production process. CNC fabrication accelerates the production process by reducing the need for manual labor. Plus, the improved accuracy and consistency of CNC machinery removes the need for fixes that would need to be accomplished manually. 

Consistent, Accurate Components

As customers become increasingly more particular about tolerances, CNC machines are well suited to deliver precision components. Because mathematical precision is built into the manufacturing process, customers can expect consistency and accuracy in the quality of their components. 

What Are the Steels Can Be Handled by CNC Bending

A CNC bending machine can handle a variety of steel types, each with different properties that affect the bending process. Here’s a breakdown of the common types of steel that can be bent using CNC bending machines:

1. Mild Steel (Low Carbon Steel)

• Description: Contains a low percentage of carbon, usually around 0.05–0.25%.
• Bendability: Mild steel is highly malleable and easy to bend. It is the most commonly used steel in CNC bending due to its excellent ductility.
• Typical Applications: Automotive parts, structural components, general fabrication, and machine parts.

2. Нержавеющая сталь

• Description: Contains chromium (at least 10.5%) and other elements like nickel, enhancing its corrosion resistance.
• Bendability: More challenging to bend due to its high strength and spring-back characteristics. CNC bending can handle grades like 304 and 316, which are most commonly used.
• Typical Applications: Kitchen equipment, medical devices, food processing, and architectural elements.

3. High Carbon Steel

• Description: Contains a higher carbon percentage (0.6–1.5%), which makes it harder and stronger.
• Bendability: Less malleable and more prone to cracking if the bend is too tight. Heat treatment might be necessary before bending.
• Typical Applications: Springs, blades, cutting tools, and high-strength components.

4. Alloy Steel

• Description: Steel mixed with various alloying elements like chromium, nickel, or molybdenum for enhanced properties.
• Bendability: Can be challenging to bend depending on the alloy composition. High-strength alloy steels may require specialized tools or heat treatment.
• Typical Applications: Aerospace components, automotive parts, and heavy machinery.

5. Tool Steel

• Description: Contains alloying elements like tungsten, molybdenum, and cobalt to increase hardness and heat resistance.
• Bendability: Typically very hard and less flexible. Specialized bending tools are required for accurate bending.
• Typical Applications: Cutting tools, molds, dies, and wear-resistant parts.

6. Galvanized Steel

• Description: Mild steel coated with a layer of zinc to prevent corrosion.
• Bendability: Easier to bend, but care must be taken to avoid cracking the zinc coating, which can lead to rusting.
• Typical Applications: Roofing, ductwork, fences, and outdoor structures.

7. Spring Steel

• Description: A type of high-carbon steel known for its high yield strength and ability to return to its original shape after bending.
• Bendability: More difficult to bend due to high strength. CNC machines with specialized tools are recommended.
• Typical Applications: Springs, clips, and washers.

8. Hot Rolled Steel

• Description: Steel that has been rolled at high temperatures, which makes it easier to work with.
• Bendability: Generally easier to bend due to its malleable nature, but it has a rough surface.
• Typical Applications: Structural components, heavy equipment, and general fabrication.

9. Cold Rolled Steel

• Description: Hot rolled steel that has been further processed at cooler temperatures for a smoother finish.
• Bendability: Offers better dimensional accuracy and is easier to bend than hot rolled steel.
• Typical Applications: Precision components, home appliances, and automotive parts.

10. Weathering Steel (Corten Steel)

• Description: A type of steel that forms a stable rust-like appearance after exposure to weather.
• Bendability: Generally easy to bend, but care must be taken due to its high yield strength.
• Typical Applications: Outdoor sculptures, bridges, and architectural elements.

Each type of steel may require different tooling, machine settings, and bending parameters. Factors like thickness, grade, bending angle, and tooling type will determine the success and quality of the bend. Proper machine calibration and using high-precision CNC tools are essential for accurate bending.

How Does a Steel CNC Bending Machine Work?

A CNC bending machine is controlled by a computer program that precisely dictates the movements of the machine’s components, allowing for accurate and repeatable bending processes.

Here’s a general overview of how a CNC bending machine works:

Design and Programming

The process begins with the design of the part to be bent using computer-aided design (CAD) software.

Once the design is complete, a CNC program is generated using computer-aided manufacturing (CAM) software. This program contains the instructions for the bending machine, specifying the angles, dimensions, and other parameters for each bend.

Material Loading

The sheet metal or material to be bent is loaded into the CNC bending machine.

The machine typically has a work-holding device, such as a clamp or back gauge, to secure the material in place and ensure accurate positioning.

Tooling Setup

The CNC bending machine is equipped with various tooling, including a punch and a die, which work together to create the desired bend.

The tooling setup is specific to the part being bent, and the appropriate tools are selected and installed in the machine.

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The CNC program, created during the programming stage, is loaded into the machine’s control unit.

The operator inputs the necessary parameters, such as material type and thickness, into the CNC control system.

Bending Process

The CNC bending machine’s computer control system precisely coordinates the movement of the machine’s components.

The sheet metal is positioned between the punch and the die.

The punch descends and applies force to the material, causing it to bend against the die.

The machine may have multiple axes of movement to accurately control the position and angle of the bend.

Automated Adjustment

Some CNC bending machines are equipped with automatic tool-changing and tool-length compensation features.

These features allow the machine to automatically adjust tooling based on the requirements of different bends, minimizing setup time and optimizing the bending process.

Quality Control

Throughout the bending process, sensors and feedback systems may be employed to ensure the accuracy of the bends.

The CNC control system monitors and adjusts parameters in real-time to maintain precision.

Unloading the Finished Part

Once the bending process is complete, the finished part is removed from the machine.

Understanding the Differences Between a Press Brake and a CNC Bending Machine

At first glance, the terms Пресс-тормоз and CNC Bending Machine may seem different, but they essentially refer to the same type of machinery used for bending metal. The difference lies mainly in historical terminology and the evolution of language. Here’s a brief history to clarify the origin of these terms and how they came to be synonymous with metal bending equipment.

Origins of the Term “Press Brake”

• Brake: In medieval times, a “brake” was a term for a crushing or pounding machine. Eventually, it became shorthand for any machine used to apply force.
• Press: The word “press” originated from the old noun “presse,” which meant to crowd or squash. Over time, it evolved to mean a machine that applies pressure.

So, “Press Brake” became the common term for what we now know as a metal bending machine—a device used to bend or shape metal sheets and plates. In modern usage, both “Press Brake” and “CNC Bending Machine” are used interchangeably, though some may simply call it a folder.

Types of Bending Methods: Bottom Bending vs. Air Bending

Before diving into the different types of press brakes, it’s important to understand the two primary bending methods: bottom bending and air bending.

Bottom Bending

Bottom bending involves forcing the metal sheet fully into the die until there’s no gap between the punch, the apex of the bent material, and the bottom of the “V.” Here’s a breakdown of the process:

• Springback: When metal is bent, it tends to return to its original flat shape. For example, bending a steel sheet to 90 degrees may result in slight springback when the pressure is removed.
• Compensation: To counteract springback, the material is bent past the target angle. Alternatively, bottom bending can be achieved by applying additional force, pushing the top tool further into the metal to lock the bend angle in place. This method, known as bottoming with penetration (or coining), requires significant force and is taxing on tools, potentially reducing their lifespan.

Air Bending

In contrast, air bending involves bending the metal without the apex touching the bottom of the “V.” It allows for greater control over the bending force, requiring less pressure. Here’s how it differs from bottom bending:

• Tooling Longevity: Air bending uses less force, making it easier on the bending tools and extending their lifespan.
• Гибкость: This method allows for more adjustable angles, reducing the stress on the tools and minimizing costs over time.

Which Industries Use CNC Bending?

CNC bending is a versatile and efficient manufacturing process that benefits a wide range of industries by reducing labor costs and delivering high-quality components. Key sectors utilizing CNC bending include aerospace, agriculture, automotive, medical, and power sports vehicles:

• Aerospace: This industry demands the highest standards of safety and performance, as aircraft components must endure extreme stress and environmental conditions.
• Automotive: Both interior and exterior automotive parts rely heavily on sheet and tube metal, requiring precise bending to ensure durability and a long lifespan for each vehicle.
• Medical: CNC bending is crucial for manufacturing medical tools with extremely small diameters, as it allows for the accurate mass production of complex and miniature components.
• Power Sports Vehicles: Components for power sports vehicles must handle frequent use and the potential for impact damage, making durability and precision essential.

Given the broad applications of CNC bending, it’s crucial to collaborate with a capable OEM supplier to ensure they can meet your specific production needs.

KRRASS Steel CNC Bending Process Capabilities

As a leading CNC manufacturer, KRRASS offers a comprehensive range of CNC machining services, including components produced by lathe machines, milling machines, wire EDM, and other advanced manufacturing processes. With full in-house capabilities for CNC bending, we streamline production, helping you save time and reduce costs.

If you are looking for an OEM supplier that prioritizes excellent customer service and precise component manufacturing, contact us today to learn how KRRASS can meet your needs.