Laser cutting is a cutting process that severs material with the heat obtained by directing a laser beam against a metal surface. Hence laser cutting is a technology that uses a laser to cut materials, and is typically used for industrial manufacturing applications. Laser cutting works by directing the output of a high power laser, by computer, at the material to be cut. The material then melts, burns, vaporizes away, or is blown away by a jet of gas, leaving an edge with a high quality surface finish.
Types of material used in Laser Cutting:
• Carbon dioxide laser (CO2): The CO2 laser produces a beam of infrared light with the principal wavelength bands. CO2 lasers are frequently used in industrial applications for cutting, boring, scribing, and engraving.
• Neodymium-doped laser (Nd): Nd lasers are used where high energy but low repetition speed are required around 1 kHz and also used for boring.
• Neodymium-doped Yttrium Aluminum Garnet laser (Nd:YAG): The Nd:YAG is a crystal that is used as a lasing medium for solid-state lasers. Nd:YAG lasers are frequently used in Medicine, Dentistry, Military and defense, manufacturing applications for very high energy pulses, boring, engraving, and trimming.
Methods to cut metals using Laser Cutting:
There are many different methods to cut metal using lasers. Some of the methods are vaporization, melt and blow, thermal stress cracking, reactive cutting etc.
• Vaporization Cutting: The process where a focused beam heats the surface of the material to boiling point and generates a keyhole. As the hole deepens and the material boils, vapor generated erodes the molten walls blowing eject out and further enlarging the hole. Non melting material such as wood, carbon and thermoset plastics are usually cut by this method.
• Melt and Blow: The process in which a high pressure gas is used to blow molten material from the cutting area, greatly decreasing the power requirement. First the material is heated to melting point then a gas jet blows the molten material out of the kerfs avoiding the need to raise the temperature of the material any further. Materials cut with this process are usually metals.
• Thermal stress cracking: The process a beam is focused on the surface causing localized heating and thermal expansion. This results in a crack that can then be guided by moving the beam. It is usually used in cutting of glass.
• Reactive Cutting: It is also known as burning stabilized laser gas cutting or flame cutting. The process in which oxygen torch with a laser beam as the ignition sources is used. It is mostly used for cutting carbon steel in thickness over 1mm. This process can be used to cut very thick steel plates with relatively little laser power.