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Fiber Over CO2

Fiber lasers undercut the operating costs of CO2 lasers

Over the past three years, fiber lasers have made significant gains in performance and reliability. Current fiber laser technology offers a more cost-effective solution than traditional CO2 lasers for cutting applications in the sheet metal fabrication industries, which is why many companies are replacing their CO2 lasers with fiber.

To understand the cost differences between operating a CO2 laser and a fiber laser, it’s important to look at the three major components of operating cost: electricity, consumables and maintenance.

CO2 lasers produce a typical wavelength of 10.6 microns with approximately 8 percent efficiency. In contrast, fiber lasers (ytterbium-doped fiber) generate a typical wavelength of 1,069 nm with approximately 38 percent efficiency. This higher efficiency translates into lower electrical operating costs, as shown in Table 1.

To understand why there is such a difference in efficiency and electricity consumption, the beam delivery system for each type of laser needs to be examined. The differences in the beam delivery systems also explain the differences in consumable and maintenance costs.

Fiber beam delivery

In fiber lasers, the active medium is ytterbium, a rare-earth element that is doped into the core of a flexible fiber optical cable. A semiconductor diode creates the light source, which is pumped through the cable. Fiber lasers have a completely solid-state design that does not require any mirrors or optical devices to transmit the laser beam.

In the thin optical cable, the laser beam has only minimal room for diffraction so a high-quality, high-powered beam is delivered to the cutting head. For the fiber laser user, this translates into cleaner cut edges and faster cutting speeds than CO2 lasers. Also, the optical cable has a high surface area-to-volume ratio, which allows for efficient cooling so there is very little energy lost to heat.

CO2 beam delivery

A CO2 laser generates a beam by electrically stimulating a gas-filled tube (a mix of helium, nitrogen and carbon dioxide) to produce light. The energized particle laser beam is directed toward the cutting head with the use of internal and external mirrors, an optical lens, flow gases and output couplers.

Near the cutting head there is potential for the beam particles to mix with air-born particles. These air-born particles can have a drastic effect on the CO2 laser beam size and quality. To prevent this type of beam contamination, it is necessary to purge the CO2 beam path with nitrogen to keep air-born particles out of the beam path.

Moisture and hydrocarbons are released during the beam activation process, which adversely affects the beam quality and reduces the laser’s power output. In addition, these byproducts can accumulate on the optical devices, causing them to wear out.

Regular maintenance and replacement of component parts is required to keep the CO2 laser in optimal operating condition. Table 2 compares the cost to generate the laser beam, that is, consumable and maintenance costs for CO2 lasers and fiber lasers.

There is a significant cost difference for electricity, consumables and maintenance between fiber lasers and CO2 lasers. So whether a company is thinking of installing its first laser or deciding to replace an older laser cutting system, it is important to consider the total operating costs before making a purchase decision.