Although effective thermal management is essential for temperature-intensive laser applications, it is far more than a necessary evil, because it makes a decisive contribution to safety, quality of results and reproducibility. In view of innovative (further) developments in the laser sector, the importance of precise temperature control is growing. Users demand highly flexible cooling systems in the form of customised solutions, maximum precision and high reliability.
In recent years, the laser industry has experienced strong growth driven by the increasing demand for precise material processing and advanced technology in various industries. Perhaps one of the most exciting trends is the increasing use of solid-state lasers in industry, especially fibre lasers, which have successively replaced CO2 lasers from various fields of application. CO2 lasers are more powerful due to their higher wavelength and are often better suited for processing non-metallic materials such as wood, acrylic, paper, plastics, leather and textiles. However, in direct comparison they require more space and cause higher acquisition and operating costs. Fibre lasers, on the other hand, are more compact and economical. They are also becoming increasingly powerful and can now cut, melt or engrave even stronger metals quickly and precisely.
Fibre lasers are most commonly applied in the automotive sector's sheet metal processing, where sheets with a material thickness of up to one millimetre are cut, welded or soldered. In this context, the extremely low tolerances not only guarantee a flawless appearance of the body in the finished vehicle but also provide the joint with the necessary strength. The implementation of fine machining operations such as the controlled and process-reliable fusion of metals requires a very high level of precision. This is where temperature comes into play, as this level of precision is only possible with optimal laser cooling. "Precisely controlled parameters, which include laser power and temperature, are crucial in metal processing to achieve the desired results", says Ingo Gdanitz, Business Development Manager at technotrans SE.
Precise temperature control as key technology
The thermal management specialist has many years of expertise in this field: technotrans solutions cool the laser and the peripherals such as the laser head or integrated motors. Temperature control ensures safety in the melting and cooling process, where a constant temperature at the laser source and the beam-emitting components is crucial, as otherwise the laser could introduce a fluctuating amount of energy – which in turn leads to inconsistent burn-in depth. "There are basically two areas with which we can indirectly influence the demanding metallurgical process: On the one hand, we support the laser's stable performance by maintaining a constant temperature level. On the other hand, our solutions prevent thermal distortion or thermal expansion in geometry", explains Gdanitz.
Looking at cooling systems as a whole, compactness is an important issue. As users demand the smallest possible footprint in their production facilities, and because a certain surface area is indispensable for heat equalisation, technotrans is focusing on the construction of slimline, columnar cooling solutions. This is because the cooling systems are equipped with air-water heat exchangers that require sufficient air flow. Despite their compact design, the systems have a high power density and energy efficiency thanks to an intelligent machine design. Their modular design also allows flexible adaptation to the individual requirements of the respective processes.
Smooth operation and low noise emissions in cooling systems are definitely an important requirement in metalworking. However, both are absolutely decisive when it comes to other applications, such as those for the medical technology segment, where laser's are mostly used in minimally invasive procedures. "In medical technology, laser powers are significantly lower than in metalworking, but our cooling solutions are used in close proximity to people who need to concentrate on their work", says Gdanitz. In addition, it is not uncommon for the coolers to be located in cleanrooms – for example in aseptic operating theatres or laboratories. In these environments, it is important to avoid air movements, which are usually caused by the integrated fans of a cooler, to the greatest possible extent.
To achieve this, technotrans uses solutions based on Peltier technology, in which refrigeration is created with Peltier elements and with the aid of plate-shaped semiconductors. Voltage is applied to these elements. As a result, one side of the plate stays cold and the other one hot. As the technotrans Peltier devices do not contain any moving parts, they do not create.vibrations, nor do they emit sound. In addition, the semiconductor plates have fast response characteristics and they directly adapt the cooling output when the voltage changes. This enables a fast and precise control of the feed flow temperature.
Dynamic control technology for energy-efficient cooling
Whether in metalworking or medical technology, very few laser processes work with continuously activated laser radiation. Instead, the laser is often switched on and off in extremely rapid cycles, for example in perforation, where laser beams create microscopically small holes at short intervals. This poses a challenge for the cooling process, as the varying heat load introduced into the system can cause a periodic fluctuation in the cooling water temperature – so-called pulsing. If this is not controlled and, for example, pulsing occurs too quickly, an uneven temperature profile will result in the cooling water system.
The possible consequences: inadequate process quality, poor reproducibility and damage to the components. technotrans meets this challenge with dynamic control technology and the use of speed-controlled compressors that regulate the required cooling capacity at high speed. "As a result, our extremely energy-efficient cooling solutions ensure constant process conditions. We only ever call up the cooling capacity actually needed at that very moment. Depending on the application, this facilitates energy savings of up to 30 per cent compared to conventional technology", says Gdanitz.
Networking increases control and optimisation potentials
Looking to the future of laser applications, one thing is already clear today: the complexity of the technology continues to increase and with it the individual requirements for thermal management. Gdanitz: "The demand for customised solutions already outweighs standard variants – and is steadily increasing." One continuing trend, for example, is system integration. Users often want more than just a physical adaptation of their cooling system through the configuration of cooling circuits and additional functions. Instead, it's more about the communication and data exchange between several devices in the process, which technotrans achieves by data networking its devices with the overall system. By equipping the cooling systems with modern control units, they are able to visualise and adjust all cooling process data at any time, either on the device itself or remotely,.for example the supply and return temperatures or volume flows, making them transparent and controllable. This is particularly helpful when it comes to error analysis, optimisation and documentation.
In addition, future technologies will soon take on a greater role, such as special high-tech lasers in semiconductor production. This is where technotrans supports innovative applications that use lithographic processes to increase the production speed of chips or the processed semiconductor starting material (wafers). Temperature control solutions specially developed and precisely matched to the application are also a basic requirement in these processes.
For further information, please visit www.technotrans.com