The process involves focusing an intense light-beam onto the cutting surface and guiding it by a mechanical process for better accuracy. As the beam intensifies, the surface of the metal melts and separates. An 'assist' gas is used to cool the lens surface and also protect it from the melted metal. Depending on the process, either oxygen or an inert gas like nitrogen or argon is used. Oxygen cutting is used for thick and reflective metals since the additional heat produced by the gas reacting with the metal in the presence of heat helps to speed up the cutting process. Compressed air which is free of oil/grease or moisture is used for thinner gauge metals and since it is used only to blow the metal fragments out of the cutting kerfs this process is also called 'clean' or 'high-pressure' cutting. Vaporization and cold-cutting are other processes by which metals can be cut.
Carbon dioxide lasers, excimer gas lasers and solid-state lasers are other types of lasers that can be used to cut metals. Both continuous and pulsed laser beams are available to suit different purposes. Lasers are calibrated according to the intensity of light emitted by laser power and a high power laser beam cuts through metal by melting the area under focus so quickly that the surrounding areas do not get heated, thus providing a clean and accurate cut. Depending on the thickness of the metal to be cut, a suitable intensity can be determined. In general, the assist gas pressure is kept low when cutting thicker materials so that the lens is kept cool and fragments are easily removed.
With metals, the laser cutting method is very effective since it is flexible, can be well controlled and since today, it is computerized, it is repeatable and allows economic and efficient use of materials. Since laser has minimal cutting-surface contact, in processes like die-stamping or punching, there is very little wastage of materials. There are several factors that are involved in providing efficient metal laser cutting, such as: Power and focus of the laser, material, thickness of the metal, warm-up and trickling of the machine, speed of cutting etc.
A trained sheet metal worker would be able to face these challenges competently, and provide clean, efficient, accurate cuts with minimum wastage of time, power and materials.