In the past, a laser often only offered one fixed beam characteristic. If the user needed to modify the beam for a different process, such as welding or cutting, or for various material types and thicknesses, they would have to go through a complex process of tuning the beam through the use of free-space optics, including the adjustment of zoom lenses, mirrors, beam combiners, fiber-to-fiber couplers and switches with motorized optics. It was inflexible, impractical and prone to user error.
Today, however, fiber laser manufacturers offer the ability to adjust and modify the beam on the fly. Many agree that since the advent of fiber technology, this automatic beam adjustment is perhaps the most significant advancement to laser processing technology in the marketplace.
As explained by nLight Inc., in a previously published article, “in metal cutting, a small beam with relatively high beam quality provides the highest speed for processing thin material. But for thicker materials, the small kerf impedes ejection of the melt. A larger and more divergent beam (lower beam quality) allows cutting of thicker plate, but comes with a speed penalty for thin sheet.”
Beyond cutting, the ability to adjust the beam is incredibly desirable for customers that also perform laser welding. When the beam can be tuned specifically for welding, customers can perform cutting and welding with the same power source and can also achieve better welding results thanks to the optimized settings provided by the ability to precisely tune the laser beam.
For fabricators and manufacturers that cut and weld a variety of materials and thicknesses and are also looking for heightened productivity and quality, – several companies are providing that capability and changing the way the industry works.
Understanding the drawbacks delivered by free-space optics when attempting to modify the laser beam, nLight developed its Corona fiber laser, which provides rapidly tunable beam quality at multi-kilowatt power levels – from 3 kW to 12 kW. To achieve this capability, the Corona employs an all-fiber technology that delivers a range of beam shapes and sizes directly from the laser output fiber.
Rapid tuning of the laser spot size optimizes machine tool performance across all metals and thicknesses. When users switch from small spot size beams for maximum optical intensity – for cutting thin material and for processing with nitrogen – to large donut-shaped beams – for cutting thick material with CO2-like edge quality – better end results are achieved.
“Corona enables the development of highly versatile machine tools so job shops and factories extend their competitive advantage,” the company explained in a recent press release. “No longer must they choose between purchasing multiple tools, accepting compromised performance from existing tools, or using complex, expensive, and fragile free-space optical technologies or beam combination methods.”
In early 2019, nLight’s Corona won the SPIE Prism Award for Innovation in Industrial Lasers. Since then, the Corona has been introduced by a range of leading tool integrators, including HK America Inc., Cy-Laser America LLC and Nukon USA.
Adjustable Mode Beam (AMB) fiber lasers from IPG Photonics offer unprecedented dual-beam laser processing capabilities with laser power up to 25 kW. AMB fiber lasers provide independent and dynamic control of the size and intensity of the core and ring beams. Any combination of a small-spot, high-intensity bright core and a larger ring-shaped beam can be configured to optimize material processing applications.
In contrast to normal laser welding, which produces spatter that becomes fused to the material surface, AMB laser welding stabilizes the keyhole and weld pool, virtually eliminating spatter, which maximizes uptime and significantly reduces rework of welded parts. AMB welding is also 50 percent faster than standard welding speeds while preserving quality and consistency.
For cutting, AMB flexibility enables high-speed, high-quality cutting across a wide range of thicknesses and materials with superb edge quality and low surface roughness without the need for multiple lasers or accessories. IPG can offer the lowest central core diameter of 50 microns, which translates to high productivity in thinner material cutting, coupled with the larger diameter ring mode for improved edge quality in thicker materials.
IPG also offers AMB fiber lasers with a high peak power option for cleaner and faster piercing, which allows cutting to begin sooner that drastically reduces cycle times, reduces material waste with dense part nesting and increases overall finished part quality.
Amada’s Locus Beam Control (LBC) technology allows users to manipulate the laser beam to create an infinite number of locus patterns and, in turn, enhance their machine’s cutting performance. With the beam-forming technology, users can control kerf width for optimal efficiency based on the material type and thickness of material they are processing. It also allows users to cut at higher speeds, raise cut quality and improve overall productivity. The technology features three modes:
Productive mode: Delivers significant productivity increases, especially when cutting stainless steel and aluminum. For nitrogen non-oxidizing cutting of medium-thick stainless steel and aluminum, processing costs can be reduced by up to 75 percent while cutting speeds can be twice as fast as conventional machines.
Quality mode: Improves overall cutting quality, specifically seen in improved surface roughness and the elimination of dross. Surface roughness can be reduced by approximately 50 percent and dross can be minimized to less than 10 micron when compared to conventional machines.
Kerf control mode: Enables long-term stable processing for lights-out and automated processing. By oscillating the beam, kerf width can be controlled to 2.5 times wider than conventional models. Automated take-out equipment is also improved for stable processing and part removal.
Overall, LBC, which is featured in Amada’s new Ventis 3015 AJ fiber laser system, allows the machine to retain high-efficiency cutting and high-energy density. Thanks to the new technology, the Ventis achieves cutting speeds up to three times faster than conventional laser cutters while also delivering superior edge quality. In contrast, conventional laser cutters experience reductions in energy density as material thicknesses increase, which leads to significant reductions in overall efficiency.
In late 2018, the Ventis 3015 AJ featuring the LBC technology won the MM Award at Euroblech. The Ventis made its North American debut at Fabtech 2019.
Coherent’s Highlight FL-ARM
The Coherent multi-kilowatt adjustable ring mode fiber laser (HighLight FL-ARM) delivers superior results in a variety of challenging welding tasks, such as zero-gap welding of zinc-coated steel, copper welding and welding of aluminum without the use of filler wire and with minimal spatter and no hot cracking. It employs a dual-core delivery fiber to produce a central spot surrounded by a concentric ring of laser light.
The unusual configuration of the FL-ARM allows for power levels in the center and the ring to be independently adjusted and modulated on the fly to achieve a virtually unlimited number of possible combinations. The power in the center and the ring can be independently adjusted on demand over a range of 1 to 100 percent of the nominal maximum output and even be independently modulated at repetition rates of up to 5 kHz. The ability to precisely control the intensity distribution of the laser spot allows the user to maximize the stability of the energy/material coupling efficiency, keyhole and melt pool during the welding process. This is what consistently produces superior results.
Coherent developed the technology in response to users seeking to improve their part quality, increase production throughput and reduce process costs. The company understands that its individual users require specific “process recipes” for their particular applications and, therefore, also delivered its CleanWeld initiative in conjunction with its FL-ARM technology. This approach delivers up to 80 percent less spatter, minimal cracking and porosity and up to 40 percent less laser power consumption in certain welding processes.
FL-ARM lasers are available in nominal output powers ranging between 2 kW and 10 kW. They are also available with an optional fiber-fiber switch, which allows a single laser to sequentially power two separate workstations or processes for maximum process utilization and economy.
Trumpf’s BrightLine technology is also well-suited for welding operations. The company’s TruDisk lasers are now available with BrightLine Weld, a feature that delivers flexible distribution of the laser output between the inner and outer fiber core of the laser light cable. This produces different laser beams in the two cores.
Additionally, the BrightLine Weld system positions one beam on top of the other on the workpiece to synchronize the beams and create the best possible results for a user’s particular needs. The approach offers significant improvements in quality and, in turn, increases productivity.
Trumpf’s BrightLine Weld technology can even be retrofitted to most existing laser installations and can be applied to multiple laser outputs from a single beam source. BrightLine Weld not only increases productivity but significantly reduces or eliminates weld spatter.