Effect of auxiliary gas pressure on cutting quality

Generally, in the application of laser cutting machines, auxiliary gas is required for material cutting. The problem mainly involves the type and pressure of auxiliary gas. Generally, the auxiliary gas can not only assist the cutting quality, the auxiliary gas is ejected coaxially with the laser beam, to protect the lens from contamination and blow away the slag at the bottom of the cutting area. For non-metallic materials and some metallic materials, use compressed air or inert gas to process the melted and evaporated materials, while suppressing excessive burning in the cutting area, so that the cutting process can continue smoothly.

Similar to aluminum and copper, the plate with relatively high reflectivity, the auxiliary gas will quickly dissociate into a plasma after being irradiated by high-energy laser. Transmit the absorbed light energy to the workpiece. The incision area is quickly heated to a sufficiently high temperature. The use of auxiliary gas in the entire cutting process is beneficial to improve the absorption rate of the metal material to the laser. For the cutting of ferrous metals, oxygen is used as an auxiliary gas. Due to the iron-oxygen reaction in the cut area, a large amount of heat is provided to accelerate the cutting process, thereby improving the cutting capacity and quality. For most metal laser cutting, active gas (as long as it is O2) is used to form an oxidative exothermic reaction with the hot metal. This additional heat can increase the cutting speed by 1/3 to 1/2.

Under the premise of ensuring auxiliary gas, the gas pressure is an extremely important factor. When cutting thin materials at high speed, a higher gas pressure is required to prevent sticking of slag on the back of the cut (hot sticking to the workpiece will also damage the cut edge). When the thickness of the material increases or the cutting speed is slow, the gas pressure should be appropriately reduced. In order to prevent the frosting of the plastic cutting edge, it is better to cut at a lower gas pressure.

Laser cutting practice shows that when the auxiliary gas is oxygen, its purity has a significant impact on the cutting quality. A 2% reduction in oxygen purity will reduce the cutting speed by 50% and result in a noticeably poorer cut quality.

In addition, the purity and pressure of the auxiliary gas also affect the cutting quality of the laser cutting machine. The higher the pressure, the higher the purity of the gas, the less scum the material adheres to, and the smoother the cut. Different gas types have different cutting speeds and effects. Generally speaking, the cutting speed of oxygen is the fastest, the cutting effect of nitrogen is the best, and the cutting cost of air is the lowest. In order to save costs, some customers directly use air as an auxiliary gas. The consequence is that the protection lens is easily polluted by air, and the maintenance cost becomes higher.