Evolution of the cutting laser: About the diode

The laser has become the ultimate “soft” cutting tool for sheet metal. It’s also one of the most quickly evolving technologies in metal fabrication. In 2007 you’d be hard pressed to find a fiber or disk cutting laser at a custom fab shop. Today they’re popping up everywhere.

According to a capital equipment spending survey from the Fabricators & Manufacturers Association, spending for new fiber lasers may soon outpace spending on new CO2 lasers. Sure, if you look at the inventory of laser cutting machines out there, CO2 lasers currently dominate, and they’ll probably continue to dominate in the coming years. But when it comes to new cutting machines, it’s all about solid-state, 1-micron-wavelength lasers.

Now, “solid state” cutting systems doesn’t just mean fiber or disk lasers. Direct-diode cutting lasers are gaining a presence. Historically, high-powered direct-diode lasers have had trouble cutting most sheet metal thicknesses because of beam quality issues. Stacked diodes of identical wavelengths don’t combine well, because the waves don’t travel in the same direction or merge neatly to produce a small spot size. In low-powered direct-diode systems, this degradation is relatively minor, but it becomes more significant as more diodes are ganged together for more power.

Today, though, laser companies are finding ways around this challenge. TeraDiode, for instance, combines diodes of slightly different wavelengths. When positioning the diodes at just the right place, the laser system can combine similar but slightly different wavelength beams from an array of diodes into one powerful beam with waves going the same direction and to the same spot.

In Europe, LIMO Lissotschenko Mikrooptik GmbH has conducted its BRILAMET (brilliant high-powered diode lasers for metal processing) research project, collaborating with Munster University of Applied Sciences in Germany. Using high-powered diode lasers (HDL), this system employs special micro-optics to connect the diode modules. The beam is guided through a specially designed cutting head with a custom nozzle. The beam cross section effectively is “shaped” for optimal cutting in sheet metal.

According to a press release, “The project showed that although a high-powered diode laser operates at a relatively modest brilliance, it is well suitable for the rapid and precise fine cutting of 6-mm-thick stainless steel.”

In the release, Dr. Jens Meinschien, vice president of innovations management at LIMO, stated, “The key ingredient here is not only the asymmetrical laser beam geometry, but also the model for predicting machining results … By making further laser beam-shaping adjustments, cutting speeds of 2.5 m/minute can even be achieved with 4-kW diode lasers.”

We’re a long way from the behemoth of a laser cutting machine (really a retrofitted plasma system) first reported in pages of The FABRICATOR back in 1974.The laser cutting playing field has become more than just the “kilowatt” race for more cutting power. Indeed, now machine makers are trying their best to make machines that can keep up with the cutting speed capabilities of the laser, especially in very thin material.

What will come next? It’s anyone’s guess, but one thing is certain: Laser innovations won’t be slowing down anytime soon.