Analysis and Solutions to Burr Problems in Laser Cutting of Sheet Metal Parts

Laser cutting focuses a laser beam on the surface of a material through a focusing lens to melt, vaporize, and ablate the material. Simultaneously, compressed gas coaxial with the laser beam blows away the molten material. The relative movement between the laser beam and the material along a predefined trajectory forms a kerf of a specific shape, completing the material cutting process. Laser cutting features high precision, narrow kerfs, smooth cutting surfaces, high speed, excellent processing quality, and compatibility with a wide range of materials. At present, laser cutting technology has been widely applied in various fields.

Most enclosures of complete electrical equipment are made of sheet metal. Laser cutting has become a common processing method in the sheet metal industry due to its advantages such as low processing cost, high efficiency, and wide material compatibility. However, every advantage has its drawback — slag adhesion and associated burrs during processing have been a persistent headache for on-site managers. Burrs on the workpiece are shown in [img].

Causes and Impacts of Burr Formation in Laser Processing

1. Based on the working principle of laser cutting and daily practice, six main causes of burr formation are summarized:
2. Deviation in the vertical position of the laser beam focus leads to unfocused energy, insufficient vaporization of the workpiece, accumulation of molten slag that is hard to remove, and easy burr formation.
3. Insufficient laser output power to effectively evaporate the metal, resulting in a large amount of molten slag and burrs.
4. Failure to meet the requirements for the type, purity, and blowing pressure of the auxiliary gas of the laser cutting machine, causing burrs.
5. Excessively slow cutting speed during laser cutting, which damages the surface quality of the cutting surface and produces burrs.
6. Prolonged operation of the laser cutting machine, leading to unstable equipment status and burr formation.
7. Deficiencies in the laser cutting equipment, such as small tooth depth and insufficient taper of the serrated tray on the laser base, resulting in excessive contact area with the plate. This causes blocked laser penetration and restricted gas flow during processing, easily leading to slag adhesion, slag rebound, and burr formation, as shown in [img].

Schematic diagram of the equipment base structure

Burrs on workpiece edges seriously affect the accuracy of subsequent bending, welding, and assembly, and pose certain safety hazards to operators. If workpieces with burrs are used in the gas tanks of ring main units produced by our company, they will greatly affect airtightness. When applied in electrical systems, falling burrs may cause short circuits or magnetic field damage, affecting the normal operation of the system or leading to other hazards.

Methods to Prevent Burr Formation in Laser Processing

Adjust Equipment Parameters

Repeatedly adjust parameters such as power, air pressure, flow rate, focal length, and feed speed for different processing materials until the optimal state is achieved. Record and save the data for subsequent batch processing. Relying solely on the machine’s preset parameters cannot produce high-quality workpieces.

Select Auxiliary Gas

The application of auxiliary gas also affects processing quality. Therefore, different auxiliary gases should be selected according to different processing materials. For example, nitrogen is recommended for cutting stainless steel. Nitrogen, often referred to as an inert gas, prevents blowholes during laser cutting and avoids instant oxidation of heated end faces, resulting in smoother and brighter cutting end faces. Gas purity is also critical; high-purity gas is preferred.

Inspect Equipment Accessories

Aged, contaminated, or damaged key components of long-used equipment will reduce processing quality and produce burrs. For instance, oil contamination, tiny cracks on the lens, or damaged nozzles will affect the transmission of laser power. These can be judged by observing whether the formed light spot is round — a round spot indicates uniform lateral distribution of laser energy and high cutting quality. Regular inspection of key components also ensures cutting quality.

Optimize Equipment Structure

In actual production, equipment structure can be improved according to different workpieces. For example, excessive contact area between the serrated tray of the laser base and the plate easily causes burrs. The tooth taper can be reduced and tooth depth increased as appropriate, as shown in [img],

Before and after the bottom support improvement: structural schematic diagram

to avoid interference with processing due to excessive contact area between the base support and the plate. The improved base support is shown in [img].

Improved base plate

Optimize Workpiece Edge Transitions

Practical production also finds that the edge transition structure of workpieces affects processing quality. Right-angle transitions are more prone to burrs than rounded or beveled transitions, as shown in [img].

It is recommended to use rounded or beveled transitions as much as possible, which also reduces stress concentration structurally.

Conclusion

Against the background of China’s vigorous market economy development, enterprises are constantly seeking truth and innovation. While competing and developing, they must not overlook the quality of existing products. Only by refining and perfecting original products before pursuing innovation can enterprises effectively enhance their comprehensive competitiveness.

A laser cutting machine is precision equipment, and its operation requires meticulous work. A single incorrect parameter can cause abnormal operation. Therefore, only rigorous and precise operation, with equipment, gas, and parameters adjusted to the optimal state, can ensure high-quality cutting.