what is a bevel cut

In traditional metalworking workshops, the sounds of grinding wheels and milling machines are often heard. For a long time, the process of "bevel cutting" after sheet metal cutting for subsequent welding has been considered a laborious and imprecise task. However, with the advancement of Industry 4.0, this situation is being completely transformed by 5-axis laser bevel cutting technology. This technology not only tilts the laser head but also represents a leap from "2D flat cutting" to "3D manufacturing."

Dynamic demonstration: 5-axis laser head performing complex bevel angles.

Why 90° Straight Cutting Can No Longer Meet Demands

Traditional 90° straight cutting technology, while dominant in early metalworking, has revealed many limitations when faced with the complex demands of modern manufacturing. Especially in welding joints, traditional straight cuts cannot provide ideal contact surfaces or molten pool space, which is critical for large thicknesses and high-strength welding products. Bevel cutting offers larger and more stable contact areas, significantly improving welding strength and connection quality. By creating edges with specific angles and geometries, bevel cutting provides the necessary molten pool space for welding, achieving results that traditional cutting methods cannot.

Additionally, with the modern manufacturing industry's focus on faster production cycles and lower manufacturing costs, traditional welding preparation processes often require multiple manual operations and fine adjustments, increasing production time and labor costs. The introduction of bevel cutting technology simplifies this process, reducing secondary processing, and providing precise welding preparation edges in a short amount of time, thereby shortening product development cycles and improving production efficiency.

What is Bevel Cutting?

Bevel cutting is the process of making an angled cut along the edges of a metal material. Unlike traditional straight cuts, bevel cuts provide specific angled edges. The main purpose of this cutting method is to provide better contact surfaces and molten pool space for the welding process, ensuring welding quality and joint strength. Bevel cutting is widely used in applications requiring high-strength welded joints, such as pressure vessels, steel structures, shipbuilding, and more.

Six Basic Types of Bevels

In modern manufacturing, selecting the right bevel type is crucial for welding integrity. Here are the six primary geometries used in the industry:

Key Bevel Terms

• Root face: The flat portion of the bevel, usually requiring additional processing to ensure welding quality during contact.
• Bevel angle: The angle between the workpiece surface and the bevel face.
• Included angle: The total angle formed between the two sides of the bevel, representing the overall opening angle of the bevel.
• Bevel depth: The vertical distance from the workpiece surface to the deepest part of the bevel face.

5-Axis Motion and Spatial Control

To achieve precise bevel cutting, the laser head must be as flexible as a human wrist. This is achieved with 5-axis 3D head motion control. The core advantages of the 5-axis system include:

• A/B Axis Rotation: In addition to the traditional X, Y, Z axes, the bevel cutting head adds two rotating axes.
• TCP Path Compensation: As the laser head moves, the "tip" (focus) must remain locked on the material's surface. Advanced equipment ensures that the focus error remains at the micron level, no matter the angle.
• Dynamic Collision Prevention: The nozzle is very close to the material during angled cutting, and software must calculate the distance in real-time to prevent collisions.

Process Comparison: Laser vs. Traditional Methods

ROI (Return on Investment) Analysis

Although a 5-axis laser bevel machine costs more than a regular laser machine, it eliminates labor costs for grinding and milling operators, as well as transport fees during the handling process. For factories with high monthly output, the additional cost of the machine can typically be recovered in 8-12 months through saved process costs.

Case Study: Bevel Cutting Brass

In metalworking, brass is known as a "tough material" due to its high reflectivity, which can damage the laser, and its high thermal conductivity, which causes the cut to produce excessive molten slag. To push the limits, we used the GWEIKE LF3015CR fiber laser machine, capable of both tube and sheet cutting, to complete a complex "Chinese-style layered screen" design.

6.1 The Power of LF3015CR: Dual-Purpose Capabilities

The LF3015CR can handle large flat sheets and is equipped with a rotating axis for tube processing. This "dual-purpose" design breaks the boundary between flat materials and tubes, providing endless creative possibilities.

6.2 Variable Angle Bevel: Bringing Metal to Life Like Wood Carving

Using LF3015CR's 5-axis motion control, we performed a variable angle cut on a 10mm thick brass sheet, simulating traditional wood carving techniques. This non-linear angle change created continuous light-reflecting surfaces that added a dynamic 3D visual effect when illuminated.

6.3 Tackling High-Reflective Materials: “Black Technology”

Brass bevel cutting is challenging due to scattered laser reflection. The LF3015CR is equipped with a laser optical protection system that absorbs excess reflective energy, protecting the fiber head from damage. Additionally, high-pressure nitrogen is used as the assist gas to quickly remove molten brass and prevent oxidation, resulting in a mirror-like, smooth finish without the need for post-grinding.

6.4 Combining Sheet and Tube: Artistic Extension

Using the tube processing function of the LF3015CR, we created matching support brackets for the brass screen, ensuring a seamless joint. This high-precision physical fit not only enhances structural stability but also visually eliminates any welding seams.

Materials Adaptation and High-End Applications

In bevel cutting, different materials require different cutting strategies. Here are the cutting strategies for common metals:

Carbon Steel Bevel Cutting Strategy

Carbon steel is a common industrial material, but when using oxygen cutting, it tends to cause edge burn. Precise control of oxygen flow is essential to reduce burns and overheating. Specific strategies include:

• Gas Selection: Oxygen is commonly used for carbon steel cutting to enhance cutting speed and surface quality.
• Speed Control: The cutting speed must be kept within a moderate range to prevent overheating while ensuring effective cutting.
• Post-Processing: In some cases, carbon steel bevel cutting requires additional cleaning to remove oxidation and slag, ensuring high welding quality.

Stainless Steel Bevel Cutting Strategy

Stainless steel bevel cutting typically uses high-pressure nitrogen to ensure the surface retains its original color and avoids oxidation. Key strategies include:

• Gas Selection: Nitrogen or high-pressure nitrogen is commonly used for stainless steel cutting to prevent oxidation and maintain a clean cut.
• Temperature Control: Due to stainless steel's poor thermal conductivity, laser power and cutting speed must be carefully controlled to avoid material overheating.
• Cutting Method: Stainless steel bevel cutting often uses smaller bevel angles to ensure joint strength and sealing properties.

Aluminum Alloy Bevel Cutting Strategy

Aluminum alloys have high reflectivity, which can lead to slag formation during cutting. Specific techniques are needed to prevent excessive slag. Strategies include:

• Gas Selection: A mixture of nitrogen and oxygen is commonly used for aluminum alloy bevel cutting to reduce slag formation.
• Precise Control: Because aluminum alloys produce more slag during cutting, precise control of gas flow and laser focus is necessary to maintain clean edges.
• Low Power, High Speed: To avoid overheating, aluminum alloy cutting generally requires lower laser power and higher cutting speeds.

Advanced Applications: When Bevel Cutting Meets Complex Tubes

Bevel cutting technology is not limited to flat materials; it plays a vital role in tube processing, especially in pipeline welding. When dealing with various pipe types, bevel cutting requires more precise control:

Pipe Intersection Bevel Cutting

In pipeline welding, bevel cutting often needs to adjust the bevel angle based on the pipe intersection line. This requires equipment to control the bevel angle precisely, ensuring joint strength and seal integrity. For complex pipe connections, the precision of the bevel directly impacts welding quality and seal performance.

3D Irregular Parts Bevel Cutting

For 3D irregular parts, such as stamped or bent components, bevel cutting requires higher precision and flexibility. Modern laser cutting machines can perform variable angle bevel cuts based on complex shapes, ensuring that every cutting surface meets welding requirements. This is especially important in fields with high precision requirements, such as aerospace and precision machinery.

Quality Standards: What Makes a “Perfect Bevel”?

• Angle Accuracy: The error should be controlled within ±1°.
• Uniform Edge: For instance, a 2mm blunt edge should be maintained without significant variation to ensure proper welding.
• Flat Surface: The surface roughness (Rz value) should be low, with no visible waviness.
• No Slag: The cut should be usable directly without requiring secondary grinding, achieving a finish that meets high-quality standards.

Frequently Asked Questions

How is laser bevel cutting different from plasma cutting?
Laser cutting offers higher precision and a smaller heat-affected zone, making it suitable for cuts requiring high accuracy and surface quality.

What materials are suitable for laser bevel cutting?
Laser bevel cutting is widely used on materials such as carbon steel, stainless steel, and aluminum alloys. Different strategies and parameters are required for each material.

How to evaluate the ROI of laser bevel cutting?
Laser bevel cutting equipment significantly reduces secondary processing and labor costs, offering high long-term ROI.

How to check the quality after bevel cutting?
Quality is typically checked by measuring angular error, dimensional error, and surface roughness to ensure the bevel meets welding requirements.