How is the effect of laser cutting affected by parameters such as auxiliary air pressure, laser power, cutting speed, and focus position?

The influence of auxiliary air pressure

In laser cutting processing, auxiliary air pressure plays a role in blowing off slag, cooling materials, and assisting combustion. Auxiliary gases include oxygen, compressed air, nitrogen, and inert gases.

Oxygen can participate in metal combustion and improve cutting efficiency, making it suitable for cutting most metals; Inert gases and air are suitable for cutting certain metal materials (such as aluminum alloys) and non-metallic materials, which can prevent material combustion.

If the auxiliary gas pressure is too high, eddy currents will appear on the surface of the material, weakening the ability to remove molten materials, leading to widening of the cutting seam and rough cutting surface; If the air pressure is too low, the molten material cannot be completely blown away, and slag will adhere to the lower surface of the material. Therefore, the auxiliary gas pressure should be adjusted during cutting to obtain the best cutting quality.

The influence of laser power

Laser power has a significant impact on cutting speed, seam width, cutting thickness, and cutting quality. The power level is determined by the material characteristics and cutting mechanism. For example, materials with high melting points (such as alloys) and high surface reflectivity (such as copper and aluminum) require higher laser power.

In laser cutting processing, there is a laser power that achieves the best cutting quality. Under this laser power, there may be phenomena of incomplete cutting or slag hanging; Above this power, it will overheat.

The impact of cutting speed

The ideal cutting speed will result in a relatively smooth line on the cutting surface, smooth material cross-section, and no burrs. When the auxiliary gas pressure and laser power are constant, there is a non-linear inverse relationship between the cutting speed and the cutting seam width. When the cutting speed is relatively slow, the action time of laser energy on the cutting seam is prolonged, resulting in an increase in the cutting seam width or an excessive width below the cutting seam, which greatly reduces the cutting quality and production efficiency.

Accelerating the cutting speed shortens the action time of the laser beam energy on the workpiece, which reduces the thermal diffusion and conduction effects, resulting in a corresponding decrease in the width of the cutting seam. But when the speed is too fast, the material of the workpiece being cut will not cut through due to insufficient cutting heat input.

The influence of focal position

The focus position is the distance from the laser focus to the surface of the workpiece, which directly affects the roughness of the cutting surface, the slope and width of the cutting seam, and the adhesion status of the molten residue. If the focus position is too advanced, it will increase the heat absorbed by the lower end of the workpiece being cut. At a certain cutting speed and auxiliary air pressure, it will cause the material being cut and the melted material near the cutting seam to flow in a liquid state on the lower surface. After cooling, the melted material will adhere to the lower surface of the workpiece in a spherical shape; If the position lags behind, the heat absorbed by the lower end face of the material being cut will decrease, so that the material in the cutting seam cannot completely melt, and some sharp and short residues will adhere to the lower surface of the board. Usually, the focus position should be on the surface of the workpiece or slightly lower, but different materials require 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 around 1/2 of the plate thickness for better results.