What is Involved in Laser Cutting Steel?

Paul Scott

Laser cutting steel is a high speed and extremely accurate method of cutting sometimes complex shapes from steel stock using high power laser beams. The lasers used in the process release large amounts of thermal energy when they focus onto the steel, thereby effectively melting a channel through the material. Laser cutting steel requires a specialized installation that typically consists of a laser head attached to a three-dimensional jig driven by a computer or a static laser head above a mobile table. The computer sends instructions to either the jig or table which then moves the laser in relation to the workpiece or vice versa. These installations may be of laser-alone or gas-assist varaints depending on the application.

A laser cutter is used to cut a sheet of steel.
A laser cutter is used to cut a sheet of steel.

High powered lasers, especially carbon dioxide (CO2) types, generate enough intense heat when focused to effortlessly cut through a wide selection of materials of varying thicknesses. This characteristic is used to good effect in laser cutting steel stock. The process produces extremely fine, clean cuts along complex profiles in steel of up to 1 inch (25 mm) thick. The lasers used are typically CO2 types with power ratings as high as 6 kW. The beam emitted by the laser head is focused onto the workpiece by a series of lenses calibrated to produce optimum cut-point performance for the material being cut.

The proper handling of lasers will lessen the chance of an injury.
The proper handling of lasers will lessen the chance of an injury.

The cut advancement inlaser cutting steel is achieved in one of two ways. The first is a mobile laser setup where the laser head itself is moved across the workpiece on a multidimensional cutting jig. The second method employs a static laser head and a mobile table which moves the workpiece around to complete the cut. Both systems are typically driven by computer numerical control (CNC) programs which allow for both extreme accuracy and high cutting speeds even when cutting very complex profiles.

The actual cut processes used in laser cutting steel fall into two categories: laser alone and gas assist. Laser-alone types use the focused laser beam alone to cut through the steel. Gas-assist systems employ a high pressure jet of gas directed at the melt point coaxially to the laser beam. This jet of gas assists in clearing melted material from the cut and also serves to improve the efficiency of the laser by creating an exothermic reaction at the cut-point. This reaction boosts the temperature of the melt pool and speeds up the cutting process even with lower powered lasers.

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