Laser cutting involves directing a focused, high-power-density laser beam at a workpiece to rapidly melt, vaporize, ablate, or ignite the material. Simultaneously, a high-speed gas stream coaxial with the beam blows away the molten material, thereby cutting through the workpiece. Laser cutting is classified as a thermal cutting method.
Laser cutting can be categorized into four types: laser vaporization cutting, laser fusion cutting, laser oxygen cutting, and laser scribing and controlled fracturing.
Laser Vaporization Cutting
A high-energy-density laser beam heats the workpiece, causing the temperature to rise rapidly. Within a very short time, the material reaches its boiling point and begins to vaporize, forming vapor.
Laser Fusion Cutting
In laser fusion cutting, the laser heats the metal material until it melts. A non-oxidizing gas (such as Ar, He, or N) is then blown through a nozzle coaxial with the beam; the high pressure of the gas expels the molten metal, creating a cut. Laser fusion cutting does not require the metal to vaporize completely, so the energy required is only one-tenth of that needed for vaporization cutting.
Laser Oxygen Cutting
The principle of laser oxygen cutting is similar to that of oxy-acetylene cutting. It uses a laser as the preheating heat source and an active gas, such as oxygen, as the cutting gas.
Laser Scribing and Controlled Fracturing
Laser scribing involves scanning the surface of a brittle material with a high-energy-density laser to vaporize a narrow groove. When pressure is subsequently applied, the brittle material fractures along this groove. Q-switched lasers and CO2 lasers are typically used for this process.