We report on industrial high-power lasers in the green wavelength regime. By means of a thin disk oscillator and a resonator-internal nonlinear crystal for second harmonic generation we provide 2000 W continuous-wave laser radiation at a wavelength of 515 nm, transported by a fiber with a 150 µm core diameter and NA 0.1. Application tests show that this laser is perfectly suited for copper welding due to the superior absorption of the green wavelength compared to IR, which allows the production of spatter-free weld spots and seams with an unprecedented reproducibility in diameter and welding depth. Now with 2 kW available power in the green, the welding performance for high quality welds can be increased compared to the already available 1 kW green laser system. The higher power leads to a larger melt volume and higher process efficiency. It is also possible to weld other materials with high quality results, for example stainless steel or aluminum. A particular advantage compared to the common IR lasers is the ability of the green laser for heat conduction mode because of the higher absorption. But due to the high beam quality also high-quality deep penetration welding is applicable, with the comfort to use scanner optics with a big field of work. This offers a whole range of new applications, e.g. remotedeburring of copper parts or producing a shiny copper surface by using shielding gas in addition. A further significant benefit of the green wavelength is that the surface condition does not influence the welding process, which allows to skip many expensive preprocessing steps such as tin-coating. Especially for e-mobility tasks the green 2 kW laser source is a suitable option for increasing productivity and quality: One example are copper foil stacks for battery production, which can be welded with higher speed and reduced spatter formation without ultrasonic pre-welding.
We report on industrial high-power lasers in the green wavelength regime. By means of a thin disk oscillator and a resonator-internal nonlinear crystal for second harmonic generation we provide 2000 W continuous-wave laser radiation at a wavelength of 515 nm. Careful shaping and stabilization of the polarization and spectral properties leads to an excellent optical-to-optical efficiency (pump to green) above 55%. The beam parameter product is designed and measured to be below 7 mm∙mrad which allows the transport with a fiber of 150 μm core diameter and standard numerical aperture of 0.1. Fiber and beam guidance optics are adapted to the green wavelength, enabling low transmission losses and stable operation. The laser, beam guidance as well as a chiller and the common customer interfaces are packaged within a compact footprint of less than 1 m². The green laser is equipped with a wide range of sensors and interfaces, enabling the user to integrate the laser in a production network and to benefit from features such as condition monitoring and predictive maintenance. Application tests show that this laser is perfectly suited for copper welding due to the superior absorption of the green wavelength compared to IR, which allows the production of spatter-free weld spots and seams with an unprecedented reproducibility in diameter and welding depth. With the new green 2 kW laser, the welding performance for high quality welds can be increased compared to the already available 1 kW system.
We present application results of welding copper with multi-kW truly continuous-wave Disk Lasers at the green wavelength of 515 nm. By spatially combining three commercially available 1 kW TruDisk 1020 lasers, 3 kW of green cw laser radiation is provided by a fiber with 200 μm core diameter. We achieved the following highlights by applying this laser source to copper sheets of different thicknesses: Sputter-free full penetration welding of 0.7 mm thickness has been demonstrated with excellent quality and a feed rate of 25 m/min, much faster than comparable IR wobble processes. In deep penetration welding mode, high-quality welds with depths of 1 mm and 2 mm have been obtained with feed rates of 18 m/min and 8 m/min, respectively, even in thick copper sheets, i.e., at maximum heat dissipation. 3 kW of green cw radiation allow welding depths <3.5 mm. Having proven the large potential of multi-kW green cw lasers, we give an overview on the current lab results on the power scaling of the disk laser sources. We demonstrate <2 kW green cw power with a BPP of 2.5 mm·mrad, as well as <3 kW green cw power with a BPP of 5 mm·mrad, both devices being realized with a compact footprint of less than 1 m2. Summarizing, our application results prove the high-power green cw disk lasers to be the perfect choice for high-performance welding of copper with an excellent quality.
As sustainability is an essential requirement, lightweight design becomes more and more important, especially for mobility. Reduced weight ensures more efficient vehicles and enables better environmental impact. Besides the design, new materials and material combinations are one major trend to achieve the required weight savings. The use of Carbon Fiber Reinforced Plastics (abbr. CFRP) is widely discussed, but so far high volume applications are rarely to be found. This is mainly due to the fact that parts made of CFRP are much more expensive than conventional parts. Furthermore, the proper technologies for high volume production are not yet ready. Another material with a large potential for lightweight design is aluminum. In comparison to CFRP, aluminum alloys are generally more affordable. As aluminum is a metallic material, production technologies for high volume standard cutting or joining applications are already developed. In addition, bending and deep-drawing can be applied. In automotive engineering, hybrid structures such as combining high-strength steels with lightweight aluminum alloys retain significant weight reduction but also have an advantage over monolithic aluminum - enhanced behavior in case of crash. Therefore, since the use of steel for applications requiring high mechanical properties is unavoidable, methods for joining aluminum with steel parts have to be further developed. Former studies showed that the use of a laser beam can be a possibility to join aluminum to steel parts. In this sense, the laser welding process represents a major challenge, since both materials have different thermal expansion coefficients and properties related to the behavior in corrosive media. Additionally, brittle intermetallic phases are formed during welding. A promising approach to welding aluminum to steel is based on the use of Laser Metal Deposition (abbr. LMD) with deposit materials in the form of powders. Within the present work, the advantages of this approach in comparison to conventional processes, as well as expected limitations are described.
One of the most important issues in automotive industry is lightweight design, especially since the CO2 emission of new cars has to be reduced by 2020. Plastic and fiber reinforced plastics (e.g. CFRP and GFRP) receive besides new manufacturing methods and the employment of high-strength steels or non-ferrous metals increasing interest. Especially the combination of different materials such as metals and plastics to single components exhausts the entire potential on weight reduction. This article presents an approach based on short laser pulses to join such dissimilar materials in industrial applications.
Until now, diode laser concepts were used in applications in the multi-kilowatt range, in which
actively cooled diode bars were used and combined via stacking. Per diode stack, laser outputs of
just over a kilowatt can be achieved. If outputs of several kilowatts are to be achieved, the radiation
of several stacks must be combined. A multi-kilowatt laser with industrially useful beam quality can
only be realized through appropriate procedures such as wavelength or spatial combining. The
beam quality of the coupled stacks corresponds to the quality of the individual stacks. If the beam
quality of such systems is pushed to the limit of the feasible, this reduces the efficiency of the total
Today, such conventional fiber delivered diode lasers with a beam quality of about 100 mm*mrad
achieve an outstanding efficiency of about 40%, but can only be used for laser soldering or other
surface processing. With conventional diode lasers, if the beam quality is improved to about 40
mm*mrad, the efficiency falls to about 32%. In order to tap all the efficiency advantages of direct
application of diode lasers and further improve the beam quality, TRUMPF has implemented a new
concept in its direct diode lasers of the TruDiode series. The basis of this concept is the use of a
fiber-coupled diode module with previously unachieved technical output characteristics. Another
major advantage of the approach is that the diodes are passively cooled. This paper will highlight
those characteristics, as well as provide technical details of the TruDiode series, extremely low
running cost and associated application fields.
While the Disk laser concept was invented in the early 90s, the first industrial products were
available in the beginning of this decade. Since then, the disk laser is used in mass production
and serves a large variety of application fields. The output power per disk has continually
increased and reached a level of 2.5 kW per disk in 2007. As of today, the disk principle has not
reached any fundamental limit regarding output power per disk or beam quality, and offers many
advantages over other high power resonator architectures.
In early 2009 TRUMPF released a new series of industrial disk lasers. This series is based on
an output power of 4 kW per disk. Scalability of output power is achieved by serial coupling of
several disks without influencing the beam quality of the system, with output powers of up to 16
kW at work piece. The new TruDisk laser series has incorporated several advancements
compared to older generation disk lasers, which have allowed a considerable reduction of
running cost, investment cost and footprint.
This paper will explain important details of the TruDisk laser series and process relevant
features of the system, like pump diode arrangement, resonator design and integrated beam
guidance. In addition, advances in applications in the thick sheet area and very cost efficient
high productivity applications like remote welding, remote cutting and cutting of thin sheets will
The disk laser concept aggregates high efficiency,
excellent beam quality, high average and peak power
with moderate cost and high reliability. Therefore it
became one major technology in industrial laser
material processing. In several large scale installations
in the automotive industry, high power cw- systems
make already use of the high brightness and high
efficiency of disk lasers, e.g. in remote welding [1,2].
Other applications including cutting, drilling, deep
welding and hybrid welding are arising.
This report highlights the latest results in cw disk laser
development. A 1.5 kW source with a beam parameter
product (BPP) of 2 mm mrad is described as well as
the demonstration of a 14 kW system out of three disks
with a BPP of 8 mm mrad. The future prospects
regarding increased power and even further improved
productivity and economics are presented. A new
industrial disk laser series with output powers up to 16
kW and a beam parameter product of 8 mm*mrad will
enable both, new applications in the thick sheet area
and very cost efficient high productive applications
like welding and cutting of thin sheets.
The quasi two-dimensional geometry of the disk laser results in conceptional advantages over other geometries.
Fundamentally, the thin disk laser allows true power scaling by increasing the pump spot diameter on the disk
while keeping the power density constant. This scaling procedure keeps optical peak intensity, temperature,
stress profile, and optical path differences in the disk nearly unchanged. The required pump beam brightness -
a main cost driver of DPSSL systems - also remains constant.
We present these fundamental concepts and present results in the wide range of multi kW-class CW-sources,
high power Q-switched sources and ultrashort pulsed sources.
Laser welding has become one of the fastest growing areas for industrial laser applications. The increasing cost
effectiveness of the laser process is enabled by the development of new highly efficient laser sources, such as the Disk
laser, coupled with decreasing cost per Watt. TRUMPF introduced the Disk laser several years ago, and today it has
become the most reliable laser tool on the market. The excellent beam quality and output powers of up to 10 kW enable
its application in the automotive industry as well as in the range of thick plate welding, such as heavy construction and
This serves as an overview of the most recent developments on the TRUMPF Disk laser and its industrial applications
like cutting, welding, remote welding and hybrid welding, too. The future prospects regarding increased power and
even further improved productivity and economics are presented.