What influence does the air pressure of a laser cutting machine have on the cutting surface?

When the air pressure is too high, the high-pressure gas will cause a significant impact on the cutting molten pool during the process of blowing away the slag. This may lead to instability of the molten pool, and wavy patterns will appear on the cutting surface, increasing the roughness of the cutting surface.

For instance, when cutting a stainless steel plate with a thickness of 10mm, if the air pressure exceeds the appropriate range by 20%, the roughness of the cutting surface may increase from the original Ra12.5μm to around Ra25μm.

Excessive air pressure will accelerate the flow rate of the cutting airflow and widen the airflow beam. During the cutting process, this will lead to an expansion of the cutting reaction zone, thereby increasing the width of the cutting seam.

Take carbon steel cutting as an example. Under normal air pressure, the width of the cutting seam may be 0.2-0.3mm. When the air pressure is too high, the width of the cutting seam may increase to 0.4-0.5mm. This not only wastes materials but may also affect the accuracy of subsequent processing.

The heat-affected zone of the material has decreased

Because high-pressure gas can quickly blow away the heat generated during cutting, the heating time of the material is shortened and the range of the heat-affected zone is relatively reduced. However, this reduction may be accompanied by other negative issues regarding cutting quality, such as an uneven cutting surface.

Too low air pressure

When the air pressure is insufficient, the slag generated during the cutting process cannot be effectively blown away from the cutting area. Slag will adhere to the cutting surface, forming a slag hanging phenomenon.

For instance, when cutting aluminum alloy, if the air pressure is too low, the slag will accumulate at the bottom of the cutting surface and may even re-solidify on it, seriously affecting the flatness and smoothness of the cutting surface.

The cutting surface is severely oxidized

When the air pressure is insufficient, the oxygen-containing air cannot be isolated from the cutting area in time. For some metal materials that are prone to oxidation, such as titanium alloys, it will cause the cutting surface to come into full contact with oxygen, resulting in oxidation of the cutting surface.

The color of the cut surface after oxidation will change. For instance, the cut surface of titanium alloy may change from the original silver-gray to yellow or black, and the oxide layer will reduce the performance of the material.

The cutting speed decreases or even the cutting fails

As the slag cannot be discharged smoothly, it will affect the continuous cutting effect of the laser beam on the material. The laser energy can be absorbed or scattered by the slag, which makes the cutting process unable to proceed smoothly and slows down the cutting speed.

In extreme cases, if too much slag accumulates, it will cause the laser to be unable to penetrate the material, resulting in cutting interruption.