Aluminum is not only synonymous with dynamism and groundbreaking properties in the lightweight automotive construction and aerospace technology sectors. It also makes everyday life easier wherever large, bulky structures have to be moved by human hands. Among such structures are the various access systems manufactured by Altec Aluminium-Technik GmbH & Co. KGaA.
The medium-sized company located in the western German state of Rhineland-Palatinate offers a diverse product portfolio, from rolling scaffolds, facade scaffolds, and flat-roof fall-protection systems to complete docking systems for aviation applications, as well as mobile maintenance stairs, work platforms, bridging structures, and industrial platform stairs.
Up to 95% of material processed and welded at Altec is aluminum, with the remaining 5% made up of steel applications. And whether welding steel or aluminum, the 50 employees at this EN 1090-1 and 1090-3-certified company can implement complex orders.
To meet these expectations, Altec has countered its relatively small size by relying on future-oriented process and production technology. “This includes cutting-edge CAD workstations, as well as fully automated robotic welding cells and advanced welding process technology,” explained Siegfried Berenz, master metalworker and international welding specialist. For 15 years he has been working mainly in the fields of aluminum welding and aluminum processing, becoming Altec’s plant manager in 2019.
As part of the growing trend toward automation, the company wanted to transfer a specific aluminum framework part (AlSi1, 2 mm) from manual production to robotic welding. To achieve that goal, Altec acquired Fronius’ cold metal transfer (CMT) technology, in combination with a TPS 320i high-tech welding system platform, which delivered high welding speeds, especially on light-gauge metal sheet.
But some of the company’s robotic welding technology was getting old. In the case of the framework structure, the aging welding technology was causing up to 70% rework from weld seam defects. In addition, the weld seam appearance could no longer meet Altec’s high demands. However, the component did not have to be produced in sufficiently high quantities to make investing in a modern robotic system economically viable.
The company’s requirements were clear: It needed a new system that was compatible with its existing robotic technology and delivered the highest possible process reliability to ensure an almost zero failure rate. To save time, it needed to be able to weld in a single operation. Because of the round style and semicircular preparation of the rung, the unmanipulated welding process ran through the vertical-up seam, flat position, and vertical-down seam in a single step. One process for all welds without moving the workpiece was thus a basic requirement.
At the same time, a gap of 2 mm was present in the section of the flat position because of the preparation, so the future process technology needed an especially high gap-bridging ability. In addition, to differentiate Altec from its competition in the framework structures sector, the new welding process had to produce the highest-quality weld seam appearance.
Berenz again reached out to Fronius. Extensive welding tests at Fronius Germany’s application engineering center of excellence in Neuhof-Dorfborn suggested that the Pulse Multi Control (PMC) Ripple Drive welding process variant would be the most suitable for Altec’s welding challenges.
With Ripple Drive, defined pause times are set between a number of pulses determined by the welder, during which the arc is completely switched off. This gives the weld pool time to cool down, allowing for welding to be conducted in all positions, and the necessary gap-bridging ability of 2 mm is achieved. In terms of appearance, the Ripple Drive function also generates a seam rippling effect that matches the appearance of GTAW.
The PMC functions also enable the number, shape, and size of the individual welding spots to be determined by precisely defining the pulse currents. This allows the characteristics of the GTAW-like seam pattern to be varied. However, the robot connection was still a challenge. It was necessary to combine the new TPS 320i digital high-tech welding system platform and the Fronius Robacta Drive push/pull welding torch needed for Ripple Drive with Altec’s veteran, but still fully functional, robot technology. Because of the large number of fieldbus protocols supported by Fronius, as well as the option to connect the TPSi by means of conventional digital or analog interface technology, Altec went ahead with this step.
According to Berenz, the Fronius system has enabled Altec to reduce welding times by about 20%. This is partly because the welding robot no longer has to move from the center of the weld seam in both directions. “By using Ripple Drive, it has been possible for the first time for the robot to weld from left to right in one go, through the challenging vertical-up and vertical-down positions,” said Berenz.
At the same time, weld seam defects and rework have been nearly eliminated. This is partly due to the high-precision wire feed. Every component in the welding system, from the wire drum to the contact tip, is matched to each other, which keeps the soft AlSi5 wire taut over the required 7-m feed.
“The visual appearance of the weldments has also improved significantly, making subsequent cleaning almost superfluous,” Berenz concluded.
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