Profile Welding System for Safer and More Reliable Laser Welding of Tubes and Profiles

Esta Rohr GmbH is a medium-sized company located in Siegen-Kaan-Marienborn, Germany, and specializes in manufacturing welded stainless steel tubes. With latest developments in welding technology from TIG to laser solutions, innovative production and market opportunities have emerged in this industry.

Laser Welding

The environment inside Esta Rohr's facilities has changed a great deal over the last decade. Although the factory is still full of noisy machines, the heat from the annealing lines, which was perceptible eight years ago, is conspicuously low.

Figure 1. Stainless steel tubes from 4,500 tons of steel were produced at Esta Rohr last year - with an increasing forecast.

Sven Pitzer, Technical Director at Esta Rohr, confirmed this transformation, commenting that the company has rebuilt its tube production unit, and now operates three instead of five production lines without compromising on its growth.

In fact, back in 2006, the company processed 3,000 tons of steel with four TIG and one laser lines. Since then, Esta Rohr has replaced a large number of TIG systems and is now completely dedicated to laser welding. Recently, the company laser welded tubes from about 4,500 tons of stainless steel (Figure 1).

Pitzer added that at present, TIG welded tubes are only manufactured in special cases, for instance, in complex inspection requirements for power plants and when specified in construction plans.

In these unique cases, Esta Rohr can still reconvert one of the lines to TIG. However, laser welded tubes offer a number of benefits such as more output, higher quality and less equipment, and hence the company has completely switched to laser in the interim period.

Profile Welding System and CO2Slab Lasers

Figure 2. ROFIN Profile Welding System for a safer and more reliable laser welding of tubes and profiles.

Figure 3. Diffusion cooled CO2 Slab lasers with 6kW output power, ROFIN DC 060W.

Figure 4. The new welding roller table and the PWS sensor with tracking system.

When the first laser system was commissioned in 2005, expectations were high for the novel technology. New markets had to be conquered and production was assumed to become more cost-efficient.

Esta Rohr overcame all these challenges and today, it produces approximately one million meters of tubes a year for automotive fuel delivery parts using ROFIN’s Profile Welding System (PWS) together with CO2 Slab lasers, with output powers of 4.5 to 6kW (Figures 2 and 3).

This special pipework can only be performed by laser welded tubes because the conventional TIG welding is not authorized by customers. These tubes are very unique as they are made from a particular steel alloy and can be easily shaped sans annealing; this is another reason why the hall is no longer hot like before.

Today, only two laser systems have annealing lines, whereas years ago, all five TIG systems were equipped with them. Figure 4 shows the new welding roller table and the PWS sensor that allow micrometer precise welding with excellent positioning accuracies and processing speeds.

The ROFIN PWS includes a sensor system and a beam guiding system, with computer controlled linear axes. All important functions for the operation of the laser system are controlled centrally through an integrated SPS-controller.

Automotive Market

Esta Rohr has become a leading manufacturer in the automotive market with a reputable list of customers.

A large amount of stainless pipes are developed for exhaust systems for automobile manufacturing and for this purpose quality HF-welded tubes are used. Since the major part of production concerns drinking water lines, ferritic steel is mainly processed as it is less expensive than austenitic steel and thus has a larger market share.

In addition to the automotive industry, Esta Rohr focuses on another promising market. Under the brand name SIMPLESTA, the company develops laser welded stainless steel tubes from 1.4520/AISI 439 material for closed water circuits in refrigerant circuits, heating systems, etc.

Likewise, tubes with polished inner seams have also been developed, which are ideal for manufacturing press-fittings belonging to the SIMPLESTA system. This enables builders to employ stainless steel for all pipes in their construction and saves significant costs.

A Decade of Partnership

Following the successful integration of the first laser system with the laser system, Sven Pitzer entrusted two other new laser systems to Stefan Ziesemer, Product Manager and Project Engineer at ROFIN. Pitzer has played a major role regarding the shift from TIG to laser welding and according to him ROFIN is the right partner for tube welding

ROFIN's new Weld Sensor was recently put to the test. The Weld Sensor was able to track the actual welding position with respect to the joint gap. It also provides operators a reliable view at the process, enabling them to adjust the roller pressure or the linear offset of the joined edges.

Figure 5. The PWS control panel is mounted onto an arm and allows an easy and standardized operation of all important system functions.

Frank Lohmann, Production Operation Manager at Esta Rohr, believes that in the case of sensitive automotive tubes, they can weld more safely than ever before. Through the PWS control panel mounted onto a supporting arm (Figure 5), Lohmann and his colleagues closely monitor the welding process.

An automatic correction of the welding position also takes place over the built-in regulation circuit. Quick and accurate linear drives further guarantee the highest degree of production reliability.

In addition, the thin laser weld seams have lower heat influences, which promote a minimal heat affected zone and a low combustion behavior. The fine-grained structure of the welding seam enables a high degree of molding sans the heat treatment processes that are usually needed for TIG welding.

Conclusion

Today, all of Esta Rohr's expectations have been met by their ROFIN products, and the company is planning to purchase another laser welding system.

Compared to traditional TIG welding, contact-free laser welding can attain higher process speeds. The PWS has a modular design and can be easily integrated into new and existing systems. It allows easy and safe operation and is suitable for harsh industrial environments. Similarly, ROFIN´s CO2 Slab lasers are service-friendly and low in maintenance.

About ROFIN-SINAR Laser

With more than 35 years of experience in laser technology, ROFIN has successfully focused its strategy on being an innovative leader in the industrial laser market and has consistently demonstrated its determination to deliver the most powerful and innovative manufacturing tools to a wide range of industries.

ROFIN’s global outlook, which started very early on, combined with acquisitions of other companies, contributed to ROFIN’s expansion efforts and is a key element of its corporate philosophy.

ROFIN-SINAR, ROFIN-BAASEL Lasertech, Wegmann-Baasel, Dilas Diodenlaser, Optoskand and many more essential laser companies with distinct compentencies are grouped into one concentration. The company’s numerous subsidiaries are available all over the world.

This information has been sourced, reviewed and adapted from materials provided by ROFIN-SINAR Laser.

For more information on this source, please visit ROFIN-SINAR Laser.

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