Laser Cutting

Laser cutting is broadly split into two groups - laser cutting with oxygen and laser cutting with a non-reactive gas such as nitrogen or argon.

Laser cutting with oxygen

Like oxyfuel cutting, in laser cutting the workpiece is heated to ignition temperature directly by the laser beam and then burned in an oxygen jet. High cutting speeds on sheet metal with thickness between 1mm (0.040 in.) to over 25mm (1 in.) are attained as a result of the exothermic reaction and the additional generation of energy. Laser cutting with oxygen is primarily used for unalloyed and low-alloyed steels. The purity of the cutting oxygen used is reflected directly in the attainable cutting speed.

Laser cutting of mild steel with oxygen
Laser cutting of mild steel with oxygen

Laser cutting with nitrogen

When cutting with nitrogen, the energy needed to melt the workpiece must be provided fully by the laser beam, with the non-reactive gas jet merely serving to blow out the melt.

Cutting stainless steel in the thickness range of less than 1mm to 25 mm and the cutting of other high-alloy steels and non-ferrous metals constitute the main field of application. Here, stainless steels are cut with high-purity nitrogen which maintains the corrosion resistance of the material. Certain nitride forming materials like titanium and zirconium can only be cut with argon in argon atmosphere. Mild steel is also cut with nitrogen occasionally if the oxide layer which forms during cutting with oxygen must be avoided e.g. for a subsequent painting or powder coating procedure.

Laser cutting with air

Cutting of non-metals with air has been common for a long time. However, there are very few applications where air is used cutting of metals.

The main reasons are: cut quality is generally inferior to the quality achieved with oxygen and nitrogen, especially when cutting material thicker than 1.5mm; the lifetime of the focusing lens is generally shortened due to contaminants (oil, moisture, particles) which are always present in shop air; and, changing air quality would result in frequent parameter adjustments, which are generally disregarded especially if the machine is supposed to run unattended or in a light-out cycle.

If cutting with air can meet the required cut quality, thorough calculations should include compressed air (electricity, maintenance, spare parts for the compressor), optics, system shutdown and production failure rate.

Laser sublimation cutting

The material is vaporised spontaneously in laser sublimation cutting. This method is used predominantly for cutting wood or fabrics. In metal processing, very high intensities, which could only be provided using super-pulse operation, would be needed. The method is only used in special cases due to the low feed rate it is associated with.

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