CO2 Lasers Maintain Their Momentum

Paula M. Powell

Even in last year’s somewhat slow market, CO₂ laser technology remained a strong contender in industrial laser applications — cutting and welding in particular. The technology also made incremental gains in applications such as cladding and marking.

For the third quarter, David Hoffman, industry economist with The Association for Manufacturing Technology in McLean, Va., reported a 10 percent increase in CO₂ laser shipments to roughly $55 million over the prior quarter, with total shipments for the 42 laser manufacturers surveyed reaching $86.03 million. Hoffman doesn’t predict any surprises in the year-end survey, either, and fully expects CO₂ lasers to retain the largest share of market demand, even as shipments for other laser types begin to pick up.

There are two basic schools of thought on how to excite the gas in this laser type: radio-frequency or DC excitation, both of which will be discussed further in the following features. Engineers at Coherent Inc. in Bloomfield, Conn., see maintenance-free benefits of radio-frequency-excited sealed slab technology increasingly giving CO₂ lasers an edge in lower-power applications. Nevertheless, Kevin Laughlin, vice president of sales and marketing at PRC Laser in Landing, N.J., reports that DC-excited fast-axial-flow lasers retain their competitive edge at the higher end of multikilowatt-level processing — say, 6 kW and beyond.

That said, competition is looming on the horizon from radio-frequency-excited slab laser technology at the higher power levels. Rofin-Sinar, for example, quotes 5 kW of maximum power from one of its slab-based models. Laughlin counters that, when both upfront and operating costs are taken into account, DC-excited kilowatt-level systems are still more cost-effective. So, in some ways, the jury is still out on which technology will ultimately dominate the industrial market.

Regardless of the cavity design, equally important developments are going on in beam management. For example, remote welding capability is available with kilowatt-level laser systems. Aside from the inherent flexibility this affords, Greg LaManna, product manager for CO₂ lasers at Trumpf’s Laser Technology Center in Plymouth Township, Mich., also sees advantages in processing speed compared with certain conventional machining processes. He estimates that laser scanner welding, for instance, can be as much as six times faster than sequential resistance spot welding in components with multiple welds.

LaManna and colleagues report that it now takes only seconds to switch between different power distributions — say, Gaussian to doughnut mode — without limiting the maximum power available. For example, with the firm’s radio-frequency-excited technology, which has adaptive mode capability, a laser rated at 4 kW will not go beyond that power, regardless of the operating mode. End users thus have the option to switch a laser unit between two workstations (which helps justify its costs) and then quickly optimize the beam characteristics for each task.

Such capability is strengthening CO₂ technology’s advantages in industrial applications such as welding. According to Laughlin, a TEM00 mode laser will provide deeper penetration welding with a thinner weld bead in certain work materials, while a dimodal beam would produce a slightly wider weld bead.

The CO₂ laser is at an interesting stage in its evolution. Competition among various cavity designs, as well as competition from emerging technologies such as fiber lasers, will only continue to heat up. However, even as the collective competition gains strength, laser manufacturers also continue to fine-tune this laser type. No one can argue against its fairly long history as a reliable laser processing system. It will be difficult to shake many industrial users out of that comfort zone — at least in the near term.