How to control the cutting quality of fiber laser cutting machine

How to control the cutting quality of fiber laser cutting machine, we consulted MORN’s senior operation technology of fiber laser cutter, and summarized the following 5 points:

1.  The influence of focus position adjustment on cutting quality

Since laser power density has a great influence on cutting speed, the choice 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 for material cutting; but its disadvantage is that the focal depth is very short and the adjustment margin is small, generally suitable for high-speed cutting of thin materials. Since the long focal length lens has a wider focal depth, as long as it has sufficient power density, it is more suitable for cutting thick workpieces.

In the whole cutting process, ensuring the constant relative position of the focus and the workpiece is an important condition for obtaining stable cutting quality. Sometimes, the lens is heated due to poor cooling during operation, which causes the focal length to change, then it  requires timely adjustment of the focal position.

When the focus is at a better position, the slit is smaller and the efficiency is higher, and better cutting speed can obtain better cutting results. In most applications, the beam focus is adjusted to just under the nozzle. The distance between the nozzle and the surface of the workpiece is generally about 1.5 mm.

2. The influence of cutting speed on cutting quality

For a given laser power density and material, the cutting speed conforms to an empirical formula. As long as the cutting speed is above the pass threshold, the cutting speed of the material is proportional to the laser power density, that is, increasing the power density can increase the cutting speed. The power density referred to here is not only related to the laser output power, but also related to the beam quality mode. In addition, the characteristics of the beam focusing system, namely the size of the focused spot also have a great influence on laser cutting.

Especially for metal materials, under the condition that other process variables are kept constant, the laser cutting speed can have a relative adjustment range and still can maintain a satisfied cutting quality. This adjustment range appears slightly width than thick parts when cutting thin metals. Sometimes, the slow cutting speed can also cause the discharge of the hot melt material to ablate the surface of the opening, making the cut surface very rough.

3.The influence of laser output power on cutting quality

For continuous wave output fiber laser source, the size of the laser power and the quality of the mode will have an important impact on cutting. In actual operation, a higher power is often set to obtain a higher cutting speed, or to cut thicker materials. But the beam mode (the distribution of beam energy on the cross section) is sometimes more important, and when the output power is increased, the mode often becomes slightly worse. During the entire effective working life of the laser, the modes are not consistent. The condition of the optical components, subtle changes in the laser working gas mixture and flow fluctuations all will affect the mode mechanism.

4. The influence of cutting procedures on cutting quality

According to the technological requirements of the product, set a suitable cutting program is very important. In the daily production and processing process, we may need to use fiber laser cutting machine to cut different patterns, and need different cutting techniques. Our operators need to set up suitable cutting procedures according to different cutting techniques to obtain good craftsmanship in a short time.

5. The impact of layout plan on cutting quality

It is necessary to formulate an excellent layout plan under the premise of quality assurance. When we get the raw materials, firstly we should consider how to reduce the cutting path to avoid repeated cutting and improve cutting efficiency.

In summary, although the factors affecting the laser cutting machine are more complicated, the cutting speed, focus position and laser output power, cutting procedure, and layout plan are five very important variables. In the cutting process, if the cutting quality is found to be significantly worse, the factors discussed above must first be checked and adjusted in time.