Laser World of Photonics Trade Fair, Munich 2013
LASERLINE expands its Diode Laser Product Line in all Areas
Performance, Overall Efficiency and Beam Quality are in the Focus
Laserline GmbH, the market leader in diode lasers, is exhibiting during the “LASER World of Photonics” trade showing a great number of new developments.
In particular, this will include an increase of the maximum offered laser power from 15 to 20 kW, a further optimization of the already very high wall plug efficiency from 42 % to 48 %, an entirely new class of diode lasers with beam parameters of 8 mm mrad, and several new features and improvements to lasers and its accessories. A completely new line of processing optics to be mentioned here.
A new benchmark in laser performance for fiber-coupled diode lasers
The previous power limit for diode lasers at Laserline was 15 kW. At Laser World of Photonics trade fair in May 2013 the maximum power level is pushed to 20 kW. This was made possible through consistent continuing development of all of the laser's components, in particular the actively cooled diode bars, the coupling technique for these individual diodes as well as the aggregates in the power supply unit. “The industry and its constantly expanding demands for available power in laser material processing required from us to increase the power from 15 to 20 kW. However, this certainly won’t be the end of it. Today we already have a good vision for the next steps necessary,” explains Managing Partner Dr. Christoph Ullmann. The necessary electrical current levels driving the semiconductor elements is only to be implemented using Laserline’s well proven active cooling. Even with the new power level, Laserline still offers a warranty of 5 years on the laser diodes – a clear statement of its dedication to quality and availability. The company also remains true to its values in the consistent coupling of laser power in an optical fiber. The beam quality of 220 mm mrad after the fiber optic is optimally suited for applications in the field of hardening and tempering of steels in particular, as well as for general heat treatment procedures. Using the great variety of optical components, the spot geometry can be adapted precisely to the application, regardless of whether round, square, rectangular, or even elliptical spots are required.
Overall electrical efficiency surpasses expectations
Due to the global trend towards reduction of energy consumption in all production procedures, Laserline also faces the challenge of making its products even more ecologically sound for the industry. As of this trade fair, the ratio between the laser output at the work piece and the electrical energy consumption has for the first time been pushed to almost 50 % and has reached a record setting level of 48 % for fiber coupled diode lasers. “At the beginning of the year, we still weren’t sure whether this demanding goal could be achieved yet,” says Volker Krause, Managing Partner. “But we succeeded – primarily through improved utilization of the light emitted by each individual laser diode bar. With reduced losses from the chip to the work piece, higher electrical-optical efficiency in the diodes themselves, and a reduction of the electrical loss level in all further aggregates in the laser, the goal of 50 % has been almost reached a year earlier than we predicted in 2011.”
Laserline expands the diode laser product line with a LDF with beam quality converter
After Laserline made presentations on a new technique for improving the beam quality of diode lasers at several conferences in 2012/2013, the step to a new product at LASER 2013 was made as a matter of course.
With the expansion of the LDF (Laserline Diode laser Fiber-coupled) series by 2 kW, 3 kW, and 4 kW lasers with a beam quality of 8 mm mrad, the diode laser has conquered new territory. The radiation of a diode laser is internally coupled into an active fiber. This fiber, which is referred to as the converter, generates a laser beam with substantially improved brightness at an optical-optical efficiency of over 70 %. The wavelength is only offset insignificantly by this, allowing the diode laser with conversion technology to emit just under 1100 nm, a range which is however well covered by the makers of lenses, mirrors, and optical systems.
“The new LDF 4000-8 differs from the classical fiber laser as we have taken a standard diode laser and installed an active fiber between the laser diodes and the passive fiber, resulting in a much higher beam quality," explains Volker Krause.“ Applying our technology intentionally rules the area of fundamental mode lasers out,” he adds. “Our customers want the new diode laser to be able to perform tasks like remote welding and using greater working distances in general, as well as enter into applications with a focus diameter of under
300 µm,“ comments Christoph Ullmann. “This means we will be able to position the new laser as a supplement to our successful diode lasers.”
The new lasers, which have a footprint of less than 1m², are equipped with 200 µm fibers as the standard and achieve an electrical efficiency of about 28 %. Operation is carried out using exactly the same platform as all other lasers of the LDF series. The maintenance concept with a maximum of one maintenance task per year on filters is retained, and the familiar warranty of 5 years on laser diodes still applies as well.
New processing optics for optimized uptime in the application
In addition to beam quality, the processing optics are also very important for a successful application. Laserline has therefore redesigned its overall set of optical components to perform welding, coating, hardening, or surface treatment applications. The optics are now completely made of stainless steel, have a self-adjusting geometry for the individual components and, above all, a cooling system which has been placed in the interior. The cooling water, for which there are no special requirements, is simply attached to the fiber plug. All other distributions are performed in the interior of the new series without disturbing hoses. Accidentally unconnected water lines and hoses heated up by reflection during long periods of operation, e.g. during Laser Cladding , are therefore no longer mattering.
The required cooling water for the optics can be generally supplied as part of the laser unit too. For when high water temperatures are required due to the installation site, Laserline has long offered an optional optical system cooling unit which is installed in the control cabinet as a 19” rack unit which can be operated without condensation even in tropical environments.
Laser welding applications are expanded by the LDF 4500-30
With the achievement of a beam quality of 30 mm mrad in a diode laser with 4 kW of power, the use of this technology in car body welding and other applications began in 2011 and since then former Laser technologies in such applications is getting replaced. Thus, an increase in power to 4.5 kW is now the consequently taken step to position the diode laser for even more laser welding applications using a 600 µm fiber. The proven technology is retained, and the new power limit is achieved using a higher power per diode bar. In the automobile industry, the fact that lasers with the same 600 µm fibers are used for welding as for brazing is especially advantageous. The user can simply use a different numeric aperture, and the maintenance department of the plant requires only one type of fibers as a potential spare part. The high effectiveness, small footprint, and mobility of the device perfectly meets the requirements of industry with 24/7 utilization times.
Flexible power sharing of up to 3 optical fibers
Rotationally symmetrical applications, above all, again and again require avoidance of distortion by a simultaneous applied intervention of laser power at two or three positions. To achieve this, the laser power of a laser has been shared among several optical fibers for years. This power sharing is something which Laserline offers now as well. The power distribution is in the ratio 50 / 50 % and 33 / 33 / 33 %.
The new innovation is that instead of (as previously) having a factory-set sharing level, the distribution can be made variable for the customer. This makes the use of power-shared lasers more flexible matching the short product cycles of the consumer electronics industry, to name only the most obvious example.
The operator can adapt the power sharing ratio using the normal control module. This is done without having to call teleservice or a technician. Changing requirements are also common in job shop applications. Here, the operator of the laser can switch between the distribution ratios without any further measures.
400 µm fibers at NA 0.12 new in the product line
In addition to increasing the power of the laser with 30 mm mrad, Laserline has now also closed the gap between this and the newly introduced beam quality of 8 mm mrad of the converted diode laser. Lasers are now offered in the LDF series with an output power of 3,000 W which are coupled in a 400 µm fiber with an NA of 0.12. This makes it possible to meet requirements for focus diameter of 300 µm with a focal length of 150 mm. 150 mm working distance is a value which has already been proven in 3-shift welding applications. As a rule of thumb, welding with a diode laser yields less spatter and generates a regular, smooth welding seams. This complete closing of the gap now lets the customer choose lasers from 8 mm mrad to 200 mm mrad and output powers of 500 W in the modular LDM product line with up to 20 kW in the flexible LDF series.
Since 2009, diode lasers have been used in the production of CFRP components. Special homogenizing optics, 3 kW of laser power, and a high process efficiency result in tape layering speeds of several meters per minute. The small footprint of Laselrine's fiber-coupled diode laser module LDM 3000-100, coupled with its high efficiency, allowed the customer to build a robust, compact, class-1 welding cell, suitable for transport on roads.
Diode lasers are revolutionizing the tape placement and winding technology for fiber-reinforced plastics. Local heating and accurate temperature control replace large autoclaves and enable one-step processing of thermoplastics. Advanced fiber placement technology with diode lasers is used by the major airplane manufacturers for fuselage and panel construction.
Increasingly, items such as aircraft parts, pressure vessels, seals and pipes that have traditionally been made of steel or aluminum are being replaced by ones made out of carbon fiber-reinforced plastic based on plastomers (CFRP). The use of CFRP improves the mechanical properties of the product and can create a weight savings of up to 70 percent. Laserline's customer - AFPT GmbH - manufactures CFRPs from tape coiled or layered in a mold. In a temporally and spatially controlled process, the diode laser efficiently heats and melts the tape material in the joint area.
AFPT GmbH built a tape placement head mounted on a robot to place CFRP tape on the 3D preform. Working in close cooperation with the customer, Laserline developed special homogenizing optics to heat the CFRP strips as they are placed. These optics produce a rectengular laser focus with a very uniform energy distribution. A coaxial multi-point temperature control regulates the laser power to ensure a safe heating of the material and keeps it below the decomposition temperature.