Laser Flame Cutting

In principle, the cutting of metals with the laser is effected by locally heating the material to above melting point at the focal point of the focused laser beam. The resulting smelt is ejected by a gas that is injected coaxially to the laser beam, so that an open cut is formed. In the case of low-alloy steels, in particular, oxygen is typically used as the cutting gas. This process, known as laser flame cutting, receives additional energy from the exothermal reaction of the material when heated to above its ignition point. The laser power required is therefore lower than for laser fusion cutting.

Today, laser flame cutting is used industrially for material up to 40 mm thick, though it must be noted that an appropriate width of cut for the ejection of the smelt must be taken into account as the thickness of the material increases.

In principle, both CO2 and Nd:YAG lasers are suitable for this application. The decision for one or other beam source is influenced by such factors as the geometry of the cut, the cycle time, the system technology and above all the material. Cutting in two dimensions, which is the most common case, is the domain of the CO2 laser, because it yields the best cost-benefit ratio. Typical cutting speeds are, for example, in the region of approx. 10 meters per minute for 1 mm, 3 meters per minute for 6mm and 1 meter per minute for 15 mm thick material.