No obstacle exists while cutting steel material of less than 10 mm by laser means. Whereas, while cutting a material of more density more powerful laser is needed, the power outlet of which should exceed 5kW. Quality may suffer as well.
Because powerful laser cutters are costly, the outlet laser method is not advantageous.
Laser equipment may have the following barriers, while cutting dense metals:
The maintaining of burning procedure implies some hardship in quasi-static condition.
While cutting, the density of materials being cut may be restricted. The reason of this is the unsteady iron cutting ridge burning. Heat at the slot should be near the combustion point to contribute further procedure. The power produced as a result of the oxide ignition reaction cannot firmly provide the continuity of ignition procedure. Permanent oxygen stream coming out of the cutting jet reduces the ridge temperature. Besides, the iron oxide coat produced in the aftermath of ignition covers the work piece face, which in its turn prevents oxygen dispersion.
After some reduction of oxygen concentration, ignition quenches.
If cutting is realized through conventional convergent shaft, it affects only a little face area. Great power thickness allows the piece heat to come to combustion point not just in the laser affected space but in other as well.
Oxygen stream diameter affecting the work piece face is bigger than that of the laser shaft. This makes ignition possible in both laser affected area and out of it.
While cutting dense metals, speed is not high. The piece face gets burnt more quickly. After operating for some time, ignition quenches as oxygen concentration decreases.
The combustion of cutting ridge occurs at intervals, which makes ridge temperature fluctuate and brings about bad notching.
It is hard to maintain permanently the purity of oxygen and pressure in the metal density direction.
Oxygen purity decrease can affect cutting property. In case of purity reduction by 0.9%, the ignition of iron and oxygen falls by 10%. If the purity decrease is 5%, the ignition reduces by 37%. The ignition rate reduction cause the decrease of power input in notching and affects speed.
Meanwhile, the iron amount in the fluid coat of cutting face grows causing the slag vicinity to increase, which makes it hard to discharge slag. In this case the beneath area of the combustion will have severe slags.
Oxygen stream purity and pressure management is necessary to achieve stable cutting.
A traditional bevel headpiece is applied in conventional mode of laser cutting, which is suitable to realize slim metal cutting.
When a dense metal is being cut, a shock wave is produced at the headpiece base, for the pressure delivery drops. Pure oxygen stream decrease and poor notching can be caused by the shock wave.
Here are keys to the solution of the problem:
Add preheating mettle and ancillary oxygen leak at the oxygen stream. Adjust the headpiece inner side to contribute airflow.
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