Laser cutting has been around since the sixties, but is now relevant due to its increasing use in industrial processes. This non-contact process uses a constant beam of light to generate heat and pressure and then precisely reshape/twist various materials as the cutting head moves across the material surface. Laser technology has a variety of functions, including cutting, drilling and engraving, depending on the intensity of the laser beam, the main constituent material used by the laser beam and the material on which it acts. Laser cutting is one of the most important processes for manufacturing sheet metal parts.

Each laser provides a continuous wavelength and can be used for a variety of purposes. There are three types of lasers: CO2 (gas lasers), fiber lasers and Nd: YAG or Nd: YVO (vanadate crystal lasers). Each uses a different base material, electrically excited with a mixture of gases or through physical diodes.

CO2 laser

A CO2 laser generates electricity through a tube filled with a mixture of gases, creating a beam of light. These tubes have mirrors at either end. One mirror is completely reflective, and the other is partial, allowing some light to pass through. Gas mixtures are usually carbon dioxide, nitrogen, hydrogen and helium. CO2 lasers produce invisible light in the far infrared range of the spectrum.

For industrial machines, the most powerful CO2 lasers can reach many kilowatts, but these are exceptions. A typical machined CO2 laser has a power of 25 to 100 watts and a wavelength of 10.6 microns.

This type of laser is most commonly used for wood or paper (and its derivatives), polymethyl methacrylate and other acrylic plastics. It is also suitable for leather, fabric, wallpaper and similar products. It is also used to process foods such as cheese, chestnuts and various plants.

CO2 lasers are generally best suited for non-metallic materials, although they can process certain metals. It can usually cut aluminum and other non-ferrous metal sheets. One can enhance the power of the CO2 beam by increasing the oxygen content, but this can be risky for inexperienced hands or machines unsuitable for such enhancement.

Fiber laser

Such machines are part of the solid-state laser group and use seed lasers. They amplify the beam using specially designed glass optical fibers that get their energy from pumping diodes. Their general wavelength is 1.064 microns, producing extremely small focal diameters. They are also usually the most expensive of all laser cutting devices.

Fiber lasers are usually maintenance-free and have a service life of at least 25,000 laser hours. As a result, fiber lasers have a longer life cycle than the other two types, and they can produce a strong and stable beam. They can manage up to 100 times more intensity than a CO2 laser with the same average power. Fiber lasers can be continuous beams, quasi-pulse or provide pulse Settings that give them different functions. One subtype of fiber laser system is MOPA, which has adjustable pulse duration. This makes the MOPA laser one of the most flexible lasers available for a variety of applications.

Fiber lasers are best suited for metal marking by annealing, metal engraving and marking thermoplastics. It applies to metals, alloys and nonmetals, and even includes glass, wood and plastics. Fiber lasers, depending on the power, can be very versatile and handle a large number of different materials. Fiber lasers are the ideal solution when thin materials are used. However, the situation is less serious for materials larger than 20 mm, although this problem can be solved with more expensive fiber laser machines larger than 6 kw.

Nd: YAG/Nd: YVO Lasers

Crystal laser cutting processes can be Nd: YAG (Neodymium-doped yttrium aluminium garnet), but more commonly they tend to use Nd: YVO (Neodymium-doped yttrium orthovanadate, YVO4) crystals. These devices have extremely high cutting capability. The disadvantage of these machines is that they are expensive, not only because of their initial price, but also because of their expected life of 8,000 to 15,000 hours (Nd: YVO4 usually has a low life) and the pump diode can be purified for a very high price.

These lasers have a wavelength of 1.064 microns and are suitable for a variety of medical, dental, military and manufacturing applications. When comparing the two Nd: YVO exhibits higher pump absorption and gain, wider bandwidth, wider pump wavelength range, shorter upper life, higher refractive index and lower thermal conductivity. In terms of continuous operation, Nd: YVO has an overall similar level of performance to Nd: YAG at moderate or high power. However, Nd: YVO does not allow pulse energies as high as Nd: YAG, and the laser lifetime is shorter.

These can be used with metals (coated and uncoated) and non-metals (including plastics). In some cases, it can even process some ceramics. Nd: YVO4 crystals combine high NLO coefficient crystals (LBO, BBO or KTP) to shift the output from near-infrared frequency to green, blue or even ULTRAVIOLET, thus providing a large number of different functions.

Due to their similar size, yttrium, gadolinium or L ions can be replaced with laser-activated rare earth ions without strongly affecting the lattice structure needed to generate the beam. This preserves the high thermal conductivity of the doped material.