Oxygen is used as a cutting gas mainly for non-alloyed and low-alloyed steels.
The jet of cutting gas oxidizes the material melted by the laser beam and blows away the melt and slag from the cutting groove. Oxidization is an exothermic (heat generating) process, which generates extra heat. This speeds up the cutting and enables the laser to cut thicker materials.
Guideline values for cutting – actual values may vary from equipment to equipment
Material
thickness
mm | Laser
power ') | Focal
distance | Cutting
nozzle
size mm | Cutting
oxygen
pressure **) | Cutting
speed
m/min |
| 2 | 1000 | 2,5" | 0,6-1,2 | 2,5-5,0 | 7 |
| 8 | 1500 | 5" | 1,0-1,5 | 0,5-1,0 | 5 |
| 20 | 2600 | 7,5" | 2,0-2,5 | 0,4-0,6 | 0,7 |
*) more powerful laser usually cuts faster
**) cutting oxygen pressure is measured at the cutting head
The values above create a high-quality, burr-free cut surface. When material thickness is increased, the pressure of cutting oxygen must be reduced to prevent a too vigorous oxidation reaction. When the material thickness is 12 mm or more, the pressure of oxygen must usually be less than 1 bar. At such low pressures, the process is highly sensitive to variations in pressure. This can be overcome by suitable regulators.
Laser cutting speed and the purity of oxygen
The quality of cutting oxygen also affects the cutting speed. Impurities slow down the oxidation. This results in a slower cutting speed. Consequently, the higher the purity of cutting oxygen, the faster the cutting speed. As the curve indicates, cutting speed increases markedly when the purity of oxygen increases. [800 W, 1 mm non-alloy steel, 3 bars].
AGA LASERLINE® laser cutting oxygen has been specifically developed to ensure maximum productivity of laser equipment when cutting steel.