The parameters of laser cutting machine are very important, which directly affects the quality and effect of cutting. Then, how to look at those professional performance parameters when purchasing laser cutting machine? The following small series will teach you how to look at it.

1. The influence of auxiliary air pressure

In laser cutting, the auxiliary air pressure can blow off the slag during cutting and cool the heat affected zone of cutting. Auxiliary gases include oxygen, compressed air, nitrogen and inert gas. For some metallic materials and nonmetallic materials, inert gas or compressed air is generally used to prevent the materials from burning. Such as the cutting of aluminum alloy materials. Active gas (such as oxygen) is used for most metal materials, because oxygen can oxidize the metal surface and improve the cutting efficiency. When the auxiliary air pressure is too high, eddy current appears on the surface of the material, which weakens the ability to remove the melt, resulting in the widening of the slit and rough cutting surface; When the air pressure is too low, the melt can not be completely blown away, and the lower surface of the material will adhere to the slag. Therefore, the auxiliary gas pressure should be adjusted during cutting to obtain the best cutting quality.

2. The influence of laser power

The laser power has great influence on cutting speed, slit width, cutting thickness and cutting quality. The required power depends on the characteristics of the material and the cutting mechanism. For example, cutting materials with good thermal conductivity and high melting point and high surface reflectivity requires a large laser power. Generally, under certain other conditions, there is a laser power to obtain the best cutting quality in laser cutting. If the power is further reduced or increased, slag hanging or over-burning will occur, which will lead to the decline of processing quality.

In addition, with the increase of discharge voltage, the intensity of laser will increase because of the increase of input peak power, so that the diameter of spot will increase and the width of slit will increase accordingly. With the increase of pulse width, the average laser power will increase and the width of laser slit will increase. Usually, with the increase of pulse frequency, the kerf width will also become wider, and when the frequency exceeds a certain value, the kerf width will decrease.

3. Influence of cutting speed

In laser cutting, the cutting speed has a considerable influence on the quality of the cutting material. The ideal cutting speed will make the cutting surface present a relatively smooth line, and there will be no slag under the material. When the auxiliary gas pressure and laser power are constant, the cutting speed presents a nonlinear inverse relationship with the kerf width. When the cutting speed is slow, the action time of laser energy in kerf is prolonged, which leads to the increase of kerf width. When the speed is too slow, the action time of laser beam is too long, the difference between the upper kerf and the lower kerf of the workpiece will be great, the cutting quality will be reduced, and the production efficiency will be greatly reduced. With the increase of cutting speed, the action time of laser beam energy on the workpiece becomes shorter, which makes the heat diffusion and heat conduction effects smaller, and thus the width of the slit decreases accordingly. When the speed is too fast, the material of the cut workpiece will not be cut through due to the lack of cutting heat input. This phenomenon belongs to incomplete cutting, and the melted material can not be blown off in time, and these melts will re-weld the slit.

4. Influence of focus position

The focal position is the distance from the laser focal point to the workpiece surface, which directly affects the roughness of the section, the slope and width of the slit and the adhesion of the molten residue. If the focus position is too advanced, it will increase the heat absorbed by the lower end of the cut workpiece. Under the condition of constant cutting speed and auxiliary air pressure, the cut material and the melted material near the slit will flow on the lower surface in liquid state, and the melted material will stick to the lower surface of the workpiece in spherical shape after cooling. If the position lags behind, the heat absorbed by the lower end face of the cut material will be reduced, so that the material can not be completely melted in the slit, and some sharp and short residues will adhere to the lower surface of the plate. Usually, the focus position should be on the surface of the workpiece or slightly lower, but different materials have different requirements. When cutting carbon steel, the cutting quality is better when the focus is on the surface of the plate. When cutting stainless steel, the focus should be about 1/2 of the thickness of the plate, and the effect is better.