The reason why we often use the laser cutting machine is that the processing quality of the laser cutting machine is good, but the premise of good processing quality is that the performance and configuration of the laser cutting machine need to reach the best before using the laser cutting machine to process good workpiece. Xintian Laser focuses on medium and low power laser cutting machine equipment. Xintian Laser summarizes three factors that affect the cutting quality of laser cutting machine: focus position, auxiliary gas, and laser output power.
1. Influence of focus position adjustment on cutting quality
Because the laser power density has a great influence on the cutting speed, the selection of lens focal length is an important issue. After the laser beam is focused, the spot size is proportional to the focal length of the lens. After the beam is focused by a short focal length lens, the spot size is very small, and the power density at the focal point is very high, which is very beneficial to material cutting. However, its disadvantages are that the depth of focus is very short and the adjustment margin is small. It is generally suitable for high-speed cutting of thin materials. Because the long focal length lens has a wide focal depth, as long as it has sufficient power density, it is more suitable for cutting thick workpiece.
After determining which focal length lens to use, the relative position of the focus and the workpiece surface is particularly important to ensure the cutting quality. Due to the high power density at the focus, in most cases, the focus position is just on the surface of the workpiece or slightly below the surface when cutting. During the whole cutting process, it is an important condition to ensure that the relative position of the focus and the workpiece is constant to obtain stable cutting quality. Sometimes, the lens is heated due to poor cooling during operation, resulting in changes in focal length, which requires timely adjustment of the focus position.
When the focus is in a better position, the slit is smaller and the efficiency is higher. A better cutting speed can obtain better cutting results.
In most applications, the beam focus is adjusted to just below the nozzle. The distance between nozzle and workpiece surface is generally about 1.0mm.
2. Influence of auxiliary gas pressure on cutting quality
Generally, auxiliary gas is required for material cutting. The problem mainly involves the type and pressure of auxiliary gas. Generally, the auxiliary gas and laser beam are ejected coaxially to protect the lens from pollution and blow away the slag at the bottom of the cutting area. For metal materials, use compressed air or inert gas to treat melted and evaporated materials, while inhibiting excessive combustion in the cutting area.
For most metal laser cutting, oxygen is used to form oxidation exothermic reaction with hot metal. This additional heat can increase the cutting speed by 1/3~1/2.
On the premise of ensuring auxiliary gas, gas pressure is a very important factor. When cutting thin materials at high speed, high gas pressure is required to prevent slag sticking on the back of the cut (hot slag sticking on the workpiece will also damage the cutting edge).
The practice of laser cutting shows that when the auxiliary gas is oxygen, its purity has a significant impact on the cutting quality. The reduction of oxygen purity by 2% will reduce the cutting speed by 50% and lead to the obvious deterioration of the cut quality.
3. The influence of laser output power on cutting quality.
For CW laser, the laser power and mode will have an important impact on cutting. In practical operation, large power is often set to obtain higher cutting speed or to cut thicker materials. However, the beam mode (the distribution of beam energy in the cross section) is sometimes more important, and when the output power is increased, the mode often becomes slightly worse. It is often found that under the condition of less than high power, the focus gets higher power density and better cutting quality. The mode is not consistent throughout the effective working life of the laser. The condition of the optical elements, the subtle changes of the laser working gas mixture and the flow fluctuations will affect the mode mechanism.
To sum up, although the factors affecting laser cutting are relatively complex, pay attention to the following three points: the focus position, auxiliary gas pressure, laser power and mode structure can cut satisfactory workpiece. In the process of cutting, if the cutting quality is found to be significantly poor, the factors discussed above should be checked first and adjusted in time.
Jinan Xintian Laser Technology Co., Ltd. specializes in the production of laser cutting machines. The laser cutting system includes: standard machine tool laser cutting system, customized system, automatic production line, etc. The products are widely used in automobile, locomotive, ship, hardware, machinery, electrical appliances, packaging, kitchenware, lighting, logo font, advertising, key body equipment, handicrafts, glasses and other industries, and have a broad customer base in China and five continents.