Laser fusion cutting is used when workpieces must meet high optical requirements without finishing. With this process, all materials that can be melted, for example metals, are separated. It has the advantage of a virtually oxide-free cutting edge and is especially suited to high-alloy steel and aluminum. Laser fusion cutting uses the reaction-inhibiting inert gases nitrogen or argon. The inert gas is sent through the kerf at pressures of up to 20 bar. The inert gases do not react with the melted metal in the kerf, but blow it down. Nitrogen or argon cools the material and prevents oxidation at the cutting edge.
Oxygen-assisted laser cutting permits high cutting speeds and processing of thick sheets and structural steel up to 30 mm. With this process, the oxygen is used as cutting gas. The laser beam penetrates into the material and heats it. In doing so, the oxygen is blown into the kerf at pressures of up to 6 bar. The heated material reacts with the oxygen. This oxidation releases further energy and supports the laser beam.
Laser sublimation cutting is used with thin and susceptible materials. The process permits complicated contours, high accuracy, and high-quality cutting edges with very little burr and low surface roughness, for example with cutting of stents in medical engineering. The laser beam alone evaporates the material and thus creates a fine kerf by removing layer after layer. The vapor pressure drives the slag out of the kerf at the top and the bottom. Typical examples of sublimation cutting are cutting of Plexiglas and wood, where direct transition from solid to gaseous state occurs.