3 Types of Laser Cutters
Learn more about the different types of laser cutters and when to use them.
A laser cutter is a machine that makes use of a high-energy beam of focused, coherent light to cut various plate or sheet materials to create flat parts. While metal is most common in industrial applications, wood and plastic can also be cut using laser cutters.
The method of beam generation for CO2, fiber, and Nd:YAG/YVO lasers are based on the same underlying physics concepts, but the physical implementation is different depending on the laser technology. This article will describe these different laser types, how they work, the differences in power, cut quality, and cost. Figure 1 shows a laser cutter in operation:
A laser cutter in operation.
Image Credit: Shutterstock.com/Parilov
1. CO2 Lasers
The main component of a CO2 (carbon dioxide) laser is a tube with a reflective mirror on one end of the tube and a partially reflective one on the other side. The CO2 in the tube is ionized by an electric field which generates light by exciting the electrons in the CO2 molecules to a higher energy state, thereby generating a photon. When a photon passes near an atom in the excited state, it causes that atom to release a photon with a wavelength of 10,600 nm, which is the characteristic wavelength of the CO2 laser.
CO2 lasers are general-purpose lasers that can cut a wide range of materials as well as sheet and plate metals. However, CO2 lasers cannot easily cut materials with high thermal absorption like copper, and materials that are highly reflective like bright stainless steel or aluminum. Depending on the laser power and machine size, a CO2 laser-cutting machine can cost anywhere from $350,000 to $1,000,000.
For more information, see our guide on CO2 laser cutters.
2. Fiber Lasers
Fiber lasers are known as solid-state lasers and make use of a dosed fiber optic cable as the lasing medium. A fiber laser beam is generated by pumping photons into one end of a quartz or boron silicate glass core fiber optic filament. These photons travel along the fiber optic filament until they reach the area that has been dosed with a rare earth element, typically neodymium. However, other rare earth elements are also used. The light is amplified by making use of fiber Bragg gratings, which have the same function as the mirrors used in other laser technologies.
Fiber lasers have a shorter wavelength of 1064 nm (for a neodymium lasing medium). This wavelength allows for higher absorption, i.e., it is better suited for reflective materials while generating less heat during cutting. Fiber lasers have higher electrical efficiency when compared to CO2 and Nd:Yag/Nd:YVO lasers. Depending on the laser power and machine size, a fiber laser-cutting machine can cost anywhere from $200,000 to $600,000.
3. Nd:YAG/Nd:YVO Lasers
An Nd:YAG laser makes use of neodymium (Nd)-doped yttrium aluminum garnet crystal (Y3Al5O12). Nd:YVO lasers make use of neodymium-doped vanadate crystals (YVO4) and operate in the same way as Nd:YAG lasers. Nd:YVO lasers have improved power stability when compared to Nd:YAG lasers and do not generate as much heat during cutting.
Similar to CO2 lasers, the crystal is placed between two mirrors—one fully reflective and one semi-reflective. The pumping photon source is a xenon/krypton flash tube or a series of laser diodes. In the case of Nd:YAG/YVO crystals, the pumping source supplies photons that raise the energy level of the neodymium ions. Once a beam of coherent, high-intensity light with a frequency of 1064 nm is generated, it is directed to the cutting head using mirrors and is finally focused to a point using a lens on the cutting head.
Nd:YAG/YVO lasers have better beam quality and higher power density when compared to fiber lasers, making them ideal for marking and etching. However, Nd:YAG/YVO lasers have much higher operating costs and single-digit energy efficiencies.
What Are the Differences in Terms of Power?
Fiber lasers have a tighter focal point, meaning they have higher power density when compared to CO2 lasers. Fiber lasers consume about one-third of the energy of a CO2 laser for the same laser output and are therefore significantly cheaper to operate. Nd:YAG/Nd:YVO Lasers have higher power densities than fiber lasers but have poor energy efficiency. Overall power can be anything from tens to thousands of watts for any of the laser technologies. In general, higher-power lasers allow for the cutting of thicker materials for all laser technologies. Most industrial metal cutting lasers have a power range between 4 and 6 kW.
What Are the Differences in Terms of Cutting Quality?
Lasers with a higher energy density like fiber and Nd:YAG/YVO will typically have a smaller focal point, meaning the cut width is narrower than lasers with a lower energy density like CO2. Fiber and Nd:YAG/YVO lasers produce a smooth cut edge compared to CO2 lasers; however, they are generally restricted to thinner materials. The cut speed and overall laser power will also have significant effects on the quality of the cut; both fast and slow cutting speeds will result in poor cut quality. Another important factor is the location of the focal point. This all means that the chosen cutting settings will often play a larger role in the potential quality of the cut than the type of laser technology.
What Are the Differences in Terms of Wavelengths?
The wavelength of the laser depends only on the materials used as the gain medium. For CO2 lasers, it is the CO2 gas molecule that produces a wavelength of 10,600 nm. Depending on the element used to dope the fiber optics in a fiber laser, the wavelength can be anything from 780 to 2,200 nm. Nd:YAG and Nd:YVO lasers both have a wavelength of 1064 nm as they both use neodymium as the gain medium.
What Are the Differences in Price?
Fiber laser cutters are significantly cheaper than CO2 lasers, with an operating cost of as little as $6.24 per hour for a 4 kW laser. CO2 lasers are expensive to purchase and maintain as the laser tube must be replaced after a certain number of hours. CO2 lasers can cost $12.73 for a 4 kW laser per hour to operate. Nd:YAG/YVO lasers are less reliable than fiber lasers and require regular, expensive maintenance and are therefore more expensive to operate.
Where is Laser Cutting Commonly Used?
In an industrial setting, a laser metal cutting machine is primarily used for sheet and plate metal cutting for a wide range of industries including automotive, aerospace, and general fabrication. Another industrial application is laser tube cutting, which makes use of specialized 4-axis laser cutting machines to cut complex profiles and openings on metal tubes.
Can Laser Cutters Cause Harm?
Yes, laser cutters can cause harm. Even low-power laser beams can cause permanent damage to the eyes. High-power lasers can cause serious burns to exposed skin. Fiber lasers require special precautions due in part to the highly reflective materials that can be cut on the machine.
This article presented the three types of laser cutters, explained what they are, and discussed when to use each of them. To learn more about laser cutters, contact a Xometry representative.
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