What are the difficulties in laser cutting of medium and thick plates?

Xintian Laser Cutting Machine

Nowadays, with the rapid development of laser cutting machine manufacturing technology and the continuous improvement of CNC technology, fiber laser processing equipment is rapidly being applied in the market of metal sheet cutting.

The development and technological updates of laser cutting equipment are becoming increasingly rapid, and many users are encountering many problems when cutting thick plates. According to market feedback information, the thickness, cutting quality, and price of cutting equipment of sheet metal processing have segmented the market application group, especially for small and medium-sized enterprise users in this field who urgently need to cut metal sheet thickness range and high-quality high-power fiber laser cutting machine complete processing equipment. So what are the difficulties of laser cutting machines in cutting thick plates?

The slit is too narrow, resulting in increased heat loss. The decrease in cutting speed increases the heat loss in the cutting area. The main form of heat loss is heat conduction, and the larger the thickness, the greater the heat conduction loss and the lower the cutting speed.

The material removal at the bottom of the incision became inconsistent, although the laser penetrated the thick plate and a large amount of slag adhered to the bottom. The formation of slag is caused by the low average cutting temperature at the bottom of the incision, which is also due to the large energy loss. In this case, the quality of the incision is usually not high.

Fiber laser has a small spot diameter and limited focal depth. Although the fiber laser cutting machine can maintain a high laser power density within the cutting depth of metal medium thick plates, it is not conducive to cutting and slag removal due to the small beam diameter and fine cutting seam. This puts forward higher requirements for the mode, spot dispersion, collimation, shaping, and range of fiber laser, and also poses significant difficulties for the process quality of fiber laser cutting metal medium and thick plates.

The role and influence of auxiliary gas quality and pressure. Take oxygen as an example; Oxygen plays a very important role in cutting medium to thick carbon steel plates using fiber optic laser. The laser is incident on the surface of the workpiece to form small holes. When the laser beam moves along the cutting direction, there are oxidized and melted substances around the small holes and cutting seams. The purity and pressure of oxygen have a significant impact on laser cutting. Oxygen with high impurities and inappropriate pressure cannot provide sufficient energy to form high fluidity molten material at the bottom of the incision, thereby reducing cutting quality and cutting speed.

By measuring the quality and pressure of auxiliary gas at different cutting positions, it was found that the narrower the cutting seam, the worse the effect of auxiliary gas, and the more difficult it is to maintain cutting quality. Therefore, ensuring appropriate cutting seam width, auxiliary gas quality, and air pressure control is crucial for cutting quality. The difference in geometric shape leads to a decrease in the quality of inflection point cutting. When laser cutting thick plates, the inclination angle of the melting front becomes prominent, which will lead to a decrease in the material’s laser absorption coefficient, thereby ensuring cutting quality by increasing cutting power and reducing cutting speed.

Laser cutting machines will be widely used in the cutting field due to their high light point conversion rate, high cutting accuracy, flexible processing ability, good cutting quality, and adaptability.