In today’s world of metal cutting, most of the fiber laser marketplace is dominated by one conversation: power. We’ve all seen the number of kilowatts painted in big bold letters on the side of flat sheet laser cutting machines. Ten, 20, now 30 kW. The sky is the limit on where the race will end, but either way: The productivity gains provided by these powers are inescapable.
Interestingly, there are two laser markets where the kilowatt race has not changed the scenery much. Both of these markets are focused on precision and versatility instead of increasing to higher powers.
The first market is tube cutting. Productivity gains in tube cutting have focused on material handling speeds and optimized nesting rather than increased laser power. In fact, increasing the power beyond 4 kW or 5 kW can cause damage to the other side of the tube, scaring or cutting unwanted features, resulting in rejected parts. The increased power tube cutting machines are instead rated on the diameter, length and linear weight of the profiles they can handle and not on how many kilowatts are available.
The second laser market bucking the power trend is flexible-format machines. Just like desktop PCs were replaced with more versatile and comfortable laptops, the market for half-sheet cutting machines is increasing rapidly. Historically, 4-ft.-by-4-ft. cutting systems were limited to sign makers cutting thin sheet metal only.
Recently, this market is experiencing a renaissance because of how affordable flexible-format machines have become for fast prototyping or small businesses that don’t need all of the overhead that a larger laser can require. To provide more capability for these high-mix, low-volume shops, flexible-format laser machine manufacturers are asking for a wider range of processing performance from the fiber laser source.
The nLight Corona technology provides a unique and powerful solution to both markets. Corona technology offers the capability to shape the laser beam inside the fiber laser, rather than using expensive optical solutions or manipulating the beam once it has left the fiber laser. By adjusting the beam inside the laser, any beam changes are made at the source, eliminating trade-offs that often accompany external solutions.
The latest iteration of Corona combines an incredibly precise 50-micron beam, designed to cut thin sheet at blazing speeds, with larger donut-shaped beams of 175 microns and 330 microns providing uncanny edge quality on thicker materials. This new Corona fiber configuration is available from 3 kW to 5 kW, which, because these market areas have not been dragged into the kilowatt race, is an ideal sweet spot.
Figure 1 illustrates the output of this fiber laser. From the 50-micron core to the 330-micron ring, the laser provides the flexibility to shift from precision cutting of thin features to excellent edge quality of thicker plate, which is desirable for tube cutting and small format machines.
Let’s first dive a little deeper into the advantages the 50-micron core provides. While the fiber laser market has become engrossed with the kW label on the box, kilowatts do not tell the entire story. The more important factor is power density. In most lasers, the preferred fiber size is 100 microns to enable cutting thick and thin materials with a compromise solution that works for all scenarios. With a 100-micron fiber, increasing the power on thin sheet materials provides more speed.
Corona technology provides photons that not only work hard, but also work smarter. With the 5-kW laser with the 50-micron core, the user can cut thin metal at the same speeds of traditional 100-micron systems with 8 kW.
Figure 2 shows a comparison of typical fiber laser cutting speeds with a traditional 100-micron core. The green bar shows what happens when a 50-micron core design is used. There is an incredible jump in speed without having to apply more power.
The tunability provided by Corona technology allows the beam diameter to be increased from 50 microns to 330 microns, delivering impressive edge quality for thicker plate, as shown in Figure 3. In addition to excellent edge quality, this larger beam enlarges the kerf making it quick and easy to remove parts from the sheet.
Combining this incredible flexibility gives both tube cutting and small-footprint markets the versatility to achieve blazing fast speeds on thinner sheet and excellent edge quality on thicker mild steel. Medium power lasers have never had so much flexibility.