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What Is Metal Laser Cutting & How Does It Work?

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The word “laser” is not actually a word. In fact, LASER is an acronym for Light Amplification by Stimulated Emission of Radiation. Since its discovery in 1960, laser technology has been adapted across many industries, enabling the use of barcode scanners, optical disk drives, law enforcement devices, and medical applications including eye surgery, tattoo removal, and skin treatments.

Another industry in which laser technology has been leveraged to great effect is manufacturing. One of the most common uses is in the cutting of aluminum and mild and stainless steel plates. The laser cutting process reliably produces highly precise cuts with a small heat effect zone and a very small kerf width making it possible to cut intricate shapes and very small holes.

So how exactly does a laser cut through a metal plate?

Think of a laser beam as an extremely intense column of light of a single wavelength, or color. For example, a typical CO2 laser’s wavelength is in the infrared part of the light spectrum, making it invisible to the human eye. Measuring just three-quarters of an inch in diameter, the beam travels from the laser resonator through the machine’s beam path, a process that creates the beam. The beam is bounced in several directions by a series of mirrors, called “beam benders” on its way through the bore of a nozzle. Flowing through this nozzle is a compressed gas, such as oxygen or nitrogen.

After the laser beam has been bounced through the beam benders and forced through the nozzle, it is focused onto the metal plate by means of a curved mirror located within a special lens in the laser tool’s cutting head. The beam must be focused precisely at this point to ensure that the density of the energy being delivered is modulated perfectly so that it is round, consistent, and centered in the nozzle.

Focusing the laser beam down to a tiny pinpoint ensures that the heat density at that spot is extreme. This effect of this process is similar to what happens when a magnifying glass is used to focus the sun’s rays onto a leaf or sheet of paper. Suddenly, a benign force is focused enough to start a fire. Focusing the wider laser beam to a pinpoint results in rapid heating, melting, and partial or complete vaporizing of the material.

When cutting lightweight or mild steel, the heat of the laser beam causes an “oxy-fuel” burning process. The gas emitted by the laser-cutting process will be pure oxygen, similar to an oxy-fuel torch. When cutting stainless steel or aluminum, the laser beam just melts through the material, after which high-pressure nitrogen is used to blow the liquified metal out of the kerf.

Manufacturing companies like EDCO Fabrication use laser-driven Computer Numerical Control (CNC) cutters to cut various metals precisely and accurately. A CNC machine has the ability to change the design patterns into numbers produced by Computer Aided Design Software (CAD). These converted numbers control the movement of the cutter, moving the CNC’s router over the metal plate in the shape of the desired part. A capacitive height control system ensures that the right distance is maintained between the end of the nozzle and the plate being cut. Because cut quality can be affected by raising or lowering the focal point, this is a critical step because it determines where the focal point is relative to the surface of the plate. Many other parameters affect the quality of the cut, but when all are calibrated correctly, laser cutting is a stable, accurate, and reliable process.

Laser cutting is more precise and consumes less energy than other methods, making it a useful and affordable tool in metal cutting and fabrication.