Laser Cutter Increasing The Power Density Increases The Cutting Speed

- Aug 14, 2017-

Many companies use Laser Cutter machine are very concerned about: how to use Laser Cutter machine to work out the quality of good workpieces? the following we have to talk about how to control the Laser Cutter machine cutting quality.

Su Weier laser summarizes several factors that affect the quality of cutting: cutting speed, focus position, auxiliary gas, laser output power and workpiece characteristics! We will give you one by one to analyze:

1. The effect of cutting speed on cutting quality

For a given laser power density and material, the cutting speed is in accordance with an empirical formula. As long as the threshold is above the 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 related not only to the laser output power but also to the beam quality mode. In addition, the characteristics of the beam focusing system, that is, after focusing the spot size also has a great impact on Laser Cutter.

The cutting speed is inversely proportional to the density (specific gravity) and thickness of the material being cut. (Such as from high-order mode to low-order mode up to TEM00); reduce the focus spot size (in the range of 500 to 2 000 W) Such as plastic, plexiglass, etc.); cutting low-density materials (such as white pine, etc.); cutting thin materials.

In particular, for metal materials, the Laser Cutter speed can have a relative adjustment range while maintaining a satisfactory cutting quality when the other process variables remain constant. This adjustment range appears to be slightly smaller than that of the thicker width. Sometimes, the slow cutting speed will lead to the excretion of hot melt material surface, so that the surface is very rough.

2. The effect of focus position adjustment on cutting quality

Since the laser power density has a great influence on the cutting speed, the choice of lens focal length is an important problem. After focusing the laser beam, the spot size is proportional to the focal length of the lens. After the beam is focused by the short focal length lens, the spot size is very small and the power density at the focal point is very high. It is very advantageous for cutting the material; but its disadvantage is that the depth of focus is very short, Small, generally more suitable for high-speed cutting thin materials. As the telephoto lens has a wide focal length, as long as there is sufficient power density, more suitable for cutting thick workpiece.

The relative position of the focus and the workpiece surface is particularly important to ensure the quality of the cutting after determining which lens to use. Due to the high power density at the focal point, in most cases, the focal position at the time of cutting is just at the surface of the workpiece, or slightly below the surface. Throughout the cutting process, ensuring that the relative position of the focus and the workpiece is constant is an important condition for obtaining a stable cutting quality. Sometimes, the lens work due to poor cooling and heat caused by changes in focus, which requires timely adjustment of the focus position.

When the focus is in a better position, the slot is smaller, more efficient, better cutting speed can get better cutting results. In most applications, the beam focus is adjusted to just under the nozzle. Nozzle and the workpiece surface spacing is generally about 1.5mm.

3. Effect of auxiliary gas pressure on cutting quality

In general, material cutting requires the use of auxiliary gas, the problem is mainly related to the type and pressure of auxiliary gas. Typically, the auxiliary gas is coaxial with the laser beam to protect the lens from contamination and blow away the bottom slag of the cutting zone. For non-metallic materials and some metallic materials, the use of compressed air or inert gas, the treatment of melting and evaporation materials, while inhibiting excessive cutting of the cutting area.

For most of the metal Laser Cutter is the use of active gas (as long as O2), the formation of hot metal and the formation of exothermic reaction, this part of the additional heat can increase the cutting speed of 1/3 ~ 1/2.

In the premise of ensuring the auxiliary gas, the gas pressure is a very important factor. When high-speed cutting of thin materials, the need for higher gas pressure to prevent the incision on the back of sticky slag (hot sticky slag to the workpiece will damage the trimming). When the material thickness increases or the cutting speed is slow, the gas pressure should be appropriately reduced. In order to prevent the plastic cutting and frosting, it is also cut with a lower gas pressure.

The Laser Cutter practice shows that when the auxiliary gas is oxygen, its purity has a significant effect on the cutting quality. A reduction in oxygen purity of 2% reduces the cutting speed by 50% and results in a significant deterioration in the quality of the incision.

4. Effect of laser output power on cutting quality

For the continuous wave output of the laser, the laser power size and mode will have an important impact on the cutting. In practice, often set the higher power to obtain a higher cutting speed, or to cut thick materials. However, the beam pattern (the distribution of beam energy in the cross section) is sometimes more important, and the pattern often changes slightly when the output power is increased. It is often found that a higher power density is obtained at a focal point that is less than a high power condition and a better cutting quality is obtained. During the full active life of the laser, the pattern is not consistent. The condition of the optical element, the fine change of the laser working mixture, and the fluctuation of the flow rate all affect the mode mechanism.

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