What are the process technologies for laser cutting?

The process flow of laser cutting is relatively simple, and the laser cutting path and parameter program are set in advance according to different products. Generally, holes are cut first, and then edges are cut. After the first piece debugging is qualified, cutting production can be directly carried out. However, it is not easy to cut the best quality product, as it is closely related to cutting materials, laser mode, power, cutting speed, auxiliary gas pressure, etc.

There are generally three working modes for lasers: continuous mode, modulation mode, and pulse mode.

In continuous mode, the output power of the laser is constant, which makes the heat entering the sheet more uniform. It is suitable for faster cutting in general situations. On the one hand, it can improve work efficiency, and on the other hand, it is also necessary to avoid heat concentration leading to the malignant transformation of the heat affected zone organization. The laser power of the modulation mode is a function of cutting speed, which can maintain a relatively low level of heat entering the sheet metal by limiting the power at each point, thereby preventing burns at the edge of the cutting seam. Due to its complex control, its efficiency is not very high and it is only used in a short period of time. Although pulse mode can be subdivided into three situations, it is essentially only a difference in strength, often chosen based on the characteristics of the material and the accuracy of the structure.

Summary: Lasers often operate in continuous output mode. In order to achieve the best cutting quality, it is necessary to adjust the feed rate for a given material, such as acceleration, deceleration, and delay when turning. Therefore, in continuous output mode, reducing power is not enough and laser power must be adjusted by changing the pulse.

The gases used in protective gas laser cutting equipment include laser working gas, protective gas, and auxiliary gas.

Cutting stainless steel and some high-strength steel generally uses nitrogen gas, which is used to prevent oxidation reactions and blow off molten materials. The purity of nitrogen gas is required to be high, and stainless steel with a diameter of 8mm or more is generally required to achieve a purity of 99.999%. Oxygen is suitable for thick plate cutting, high-speed cutting, and extremely thin plate cutting. Air is suitable for cutting aluminum plates, non-metallic and galvanized steel plates, and to some extent, it can reduce oxide films and save costs. In terms of cost, cutting carbon steel with oxygen is relatively inexpensive, and the amount of nitrogen used for cutting carbon steel is large. The thicker the stainless steel, the higher the nitrogen content and purity required, and the higher the cost. At present, the cutting cost of high-purity nitrogen is about 35-40CNY/h, which is higher than the cutting cost of using oxygen, about 10-15CNY/h.

Summary: The maximum speed of laser cutting can reach 40m/min, but in actual processing, it is often only 1/3 to 1/2 of the maximum speed, because the higher the speed, the lower the dynamic accuracy of the servo mechanism, which directly affects the cutting quality. When cutting circular holes, the higher the cutting speed and the smaller the aperture, the worse the roundness of the processed hole. Only in long straight cutting can maximum cutting speed be used to improve efficiency. In the actual cutting process, it is necessary to adjust the laser power, air pressure, and other related parameters according to the material, thickness, and relevant technical requirements of the product to achieve the optimal cutting speed suitable for the product.