Fiber vs. CO2 lasers for job shops: Clarifying the AKL controversy

As expected, I have already received comments relative to the news item I posted from last week's International Laser Technology Conference (AKL) in Aachen on fiber versus CO₂ laser cutting. First off, let me be clear on what John Powell from Laser Expertise presented from a paper he co-authored with A.F.H Kaplan of the Lulea University of Technology -- it was a "discussion of the advantages and disadvantages of both types of laser cutting technology from a commercial point of view, written from the perspective of a laser cutting job-shop owner trying to decide between buying a fiber or CO₂ laser cutting machine." His early conclusion was that the machine choice is not straightforward, and that "both machines have advantages and disadvantages."

During his introduction, Powell clarified that his analysis considered fiber laser to mean both fiber and disc lasers, and quoted Dr. Dirk Petring's (Fraunhofer ILT) comments made at last year's Industrial Laser Applications Symposium (ILAS, March 2011, Warrington, UK) comparing CO₂ and fiber lasers for cutting thin section (Powell's emphasis) metal, that "the CO₂ laser is dead." Simply put, for cutting metals thinner than 3 mm the fiber is faster and the edge quality is as good. So, for manufacturers of thin-gauge metal components, the fiber is the better choice.

For a job-shop, though, the choice is not as clear. So he investigated two machines, a 5 kW CO₂ from Trumpf and a 3 kW fiber from Bystronic. Setting aside all the detailed data these suppliers provided, Powell decided on "two basic considerations" for the potential job-shop users: what will be the cost/part produced, and how good is the cut quality?

For cutting thin-gauge stainless steel. he gives the edge to the fiber laser which is 25-50% faster than the CO₂ laser, especially when cutting large simple shapes. At 4 mm the cutting speeds converge, and above 8 mm the advantage goes to the CO₂ laser.

Looking at running costs, Powell gives the edge to the fiber laser, citing its lower maintenance cost -- although he qualified this by noting the dearth of long-term operating data for the newer fiber laser technology.

As to cut quality, he acknowledged that suppliers of both technologies have narrowed the quality differences up to 6-8 mm thicknesses, but for thicknesses above this range the CO₂ laser excels. Powell gave credit to the fiber laser for oxygen-assist cutting of mild steels where the cut edges are comparable.

The edge in cutting copper and aluminum alloys goes to the fiber laser. CO₂ lasers get the nod for cutting plastic and wood-based products. He noted, though, that most job shops only cut a small amount of these materials.

So, Powell's conclusion: if you are a job shop with a wide range of cutting requirements, you "should buy CO₂ machines until you have enough suitable work to fill the capacity of a fiber laser." For manufacturing companies making products from thin section metals, "your first choice should probably be a fiber laser." Prospective buyers, he advised, should get actual cutting trials done on typical jobs by potential suppliers of both types of machines.

Interestingly, many of the questions from the AKL audience dealt with technical aspects, which he answered. But he cautioned several times that his analysis was made from the perspective of a job-shop buyer, and consequently his two basic considerations -- cost/part and cut edge quality -- were the most important factors.