Inside Coherent, the technology powering Kemppi FastBeam 3

A powerful laser can produce an impressive weld. Producing thousands of consistent welds under real manufacturing conditions, however, requires something more: stable optical power, precise process control and technology that can withstand prolonged industrial use.

For manufacturers investing in laser welding, these factors directly influence production quality, operating costs and the long-term value of their equipment.

That is also what makes the collaboration between Coherent and Kemppi significant. Behind FastBeam 3 is a partnership connecting two areas of Finnish industrial expertise, from the physics of generating high-power laser light to the practical requirements of welding on the factory floor.

Over two decades of expertise behind the beam

Coherent has manufactured fiber lasers in Tampere since 2003. In 2020, the company designated the site its Center of Excellence for Fiber Lasers, bringing critical optical component manufacturing, laser assembly, testing and application development closer together.

The expertise developed at Coherent reaches far beyond handheld welding. It supplies high-power laser technology for industries such as automotive manufacturing, electric vehicle production and energy storage. Its industrial laser portfolio includes systems delivering up to 20 kW, with advanced beam-control technologies developed for challenging materials and high-volume production. This experience is particularly valuable in applications where even small variations in laser performance can affect weld penetration, component quality and manufacturing yield.

For FastBeam 3, Coherent manufactures the 3 kW fiber laser module at the heart of the system, combining high optical power with an architecture suitable for a handheld industrial welding machine.

"The size is a big factor," explains Aku Antikainen, Laser Application Engineer at Coherent. The challenge, he says, is achieving sufficiently high power while keeping the system compact enough for practical industrial use.

Generating 3 kW from a single laser module requires overcoming significant engineering constraints. As optical power increases, unwanted nonlinear effects such as stimulated Raman scattering become more difficult to manage. Optical losses can also generate substantial heat inside sensitive components.

At an output of 3 kW, even a 1% optical loss represents 30 watts of energy that may be converted into heat. Maintaining high optical efficiency therefore requires careful fiber design, clean optical interfaces and effective thermal management.

Coherent's single-module approach provides FastBeam 3 with the required optical output without the additional complexity of combining several laser modules.

Why stable laser power matters to every weld

Power is one of the most visible specifications on a laser welding machine. Yet for consistent industrial welding, how precisely that power is delivered matters just as much as the maximum output.

A laser must reach its commanded power quickly, avoid excessive overshoot and maintain a stable output throughout the welding operation. "If the power fluctuates or degrades over time, then you're not going to get these consistent welds," Antikainen explains.

Changes in optical output can affect the molten pool, penetration depth and weld geometry. A fluctuating beam may lead to variations along a seam, while excessive or insufficient energy can increase the risk of defects.

Coherent has made repeatability a major focus of its industrial fiber laser development. In published testing of its separate ARM laser family, 90 individual lasers set to deliver 2.575 kW demonstrated a standard deviation of just 5.4 W in measured output power, equivalent to approximately 0.2%.

Although these results relate to a different Coherent laser platform, they illustrate the company's engineering capability in achieving consistent optical output across manufactured units.

That level of manufacturing discipline is important to industrial customers because process repeatability depends on having a predictable starting point. If laser characteristics vary significantly, welding parameters may need to be adjusted between machines or over time.

Antikainen explains that Coherent's testing pays particular attention to how rapidly the laser reaches its requested power and whether that output remains stable during sustained operation.

For a production manager, the implications are practical: fewer unexpected process variations, less time spent troubleshooting and greater confidence in the consistency of finished welds.

Tested and traceable in Tampere

At Coherent, reliability is built into the manufacturing process.

According to Antikainen, components are checked at different production stages, while completed laser modules undergo functional and performance testing before delivery. These tests include verifying output power and its stability during extended operation.

"There's a footprint of everything," Antikainen explains. If a component batch proves faulty, the company can trace the issue back through its manufacturing records.

For customers, this approach has value beyond quality assurance. Industrial equipment often operates within tightly scheduled production environments where unexpected failures can interrupt multiple downstream processes.

Traceability makes investigations more systematic, while thorough testing before delivery helps reduce the risk of equipment problems entering production.

For Antikainen, the confidence that comes from this process is also a source of professional pride. "I can stand behind our products," he says, reflecting on the testing and engineering behind the lasers manufactured in Tampere.

Coherent's technology meets Kemppi's welding expertise

The laser module is only one part of what makes FastBeam 3 an industrial welding solution.

While Coherent provides the technology for generating stable, high-power laser light, Kemppi integrates it into a complete system designed around welding performance, operator usability and industrial safety.

FastBeam 3 combines its water-cooled 3 kW laser source with Kemppi's Penetration Shape Control, allowing welders to adjust beam shape, balance, oscillation and power to suit different applications.

With adjustable beam oscillation from 0–5 mm at frequencies of 20–150 Hz, welders can control how energy is distributed across the joint and adapt the weld profile to different materials and joint geometries.

This is where optical performance becomes measurable production value. A stable laser source helps deliver predictable energy to the workpiece, while Kemppi's process controls determine how that energy is applied.

Concentrating heat precisely around the joint can reduce the heat-affected zone and limit distortion in suitable applications. Less distortion can mean fewer corrective operations, less finishing work and a lower cost per finished component.

FastBeam 3 also addresses the practical requirements of industrial operation. Weld Assist guides users toward suitable starting parameters, while the water-cooled LT3 torch, optional filler-wire feeding and external chiller support varied production tasks.

The external chiller can be positioned outside the welding enclosure using 5 m or 10 m cooling hoses, helping reduce heat and noise around the operator while improving maintenance access.

For manufacturers, the benefit extends to the combination of controlled weld quality, efficient job changes, reduced secondary work and equipment designed for dependable operation.

Finnish expertise at laser speed

The strength of the collaboration lies in what each company contributes. While Coherent produces and tests the laser module in Tampere, Kemppi develops and manufactures the complete FastBeam 3 system in Lahti, integrating the laser with welding process controls, safety functions and equipment designed for industrial use.

For manufacturers, this partnership brings something particularly valuable: confidence in what goes into the machine and what they can expect from it. FastBeam 3 includes automatic laser power cut-off with redundant protection, color-coded machine status indications and a limited start window after torch contact. These built-in functions support safe operation alongside the protective equipment, training and controlled working environment required for handheld Class 4 laser welding.

Antikainen believes further developments in optical fibers and laser wavelengths will continue expanding what industrial lasers can achieve. Different wavelengths can change how materials absorb laser energy, potentially opening opportunities to process materials that are currently difficult to weld or cut efficiently.

For Kemppi, FastBeam 3 represents an important step in bringing this technology into everyday industrial fabrication.