Reliable and precise

Umbrella brand uses automated MIG welding

Fig. 1: Trier is the headquarters of alwitra GmbH + Co., an "umbrella brand" in every sense of the word
(PresseBox) ( Mündersbach, )
When architects and planners speak of an umbrella brand for roofing materials, they often mean alwitra in Trier (Fig. 1). The high quality, innovative, complete flat roofing systems from this SME in Trier are in demand throughout the world - whether for new constructions, refurbishing or unconventional architectural challenges. Products range from waterproof roofing sheets, rainwater gutters and domed roof lights to photovoltaic systems. The manufacturing stages in the production halls are even more diversified than the range of products.

A year ago, the company installed a welding robot system, equipped with a fully digital EMW Phoenix 422 RC pulse power source. "Since then the robot/power source combination has done exactly what we required of it - reliable welding, seam after seam shift after shift", summarises Albert Thömmes (Fig. 3), production manager for aluminium components at alwitra.

It is not always large and complex industrial production lines which make an investment in efficient robot operation essential. When small to medium sized businesses or craftsmen decide to use automated welding, the criteria often appear banal at first sight. However, at a closer look, the benefits soon become clear.

Ideal welding unit - lowspatter and short circuitproof

All the roof edging and wall sealing profiles as well as the composite sheets of the alwitra flat roofing systems consist of weatherresistant aluminium (Al Mg 1 and Al Mg Si 0.5-1.5 to 2.5 millimetres thick) Each individual corner of the standard and special coping profiles is welded (Fig. 4). This is done with a Metal Inert Gas (MIG) process using a pulsed arc under the inert gas argon with an Al Mg 3 additive. With its fully digital inverter technology the Phoenix power source is an "ideal welding unit" for this purpose. It provides the lowspatter and short circuitproof material transfer from the rolls of solid additive wire, which is so important for aluminium welding.

Flexible, even with high outputs

As no visible seams are welded, the main priority is the rapid and reliably reproducible production of seams. As Albert Thömmes states: "Ten years ago, our two manual MIG welding stations were supplemented with an automatic longitudinal seam welding unit. Since then, an Integral power source from German market leader EWM Hightec Welding, Mündersbach has been in operation - providing constant and utterly dependable performance (Fig. 5). Due to the planned expansion of production, we were faced with the decision to purchase either a manual or a robot welding station. We decided on an automated solution (Fig. 6a + 6b); this is quicker, and the welding is of a constantly high quality. Expensive reworking, such as is needed with manual welding is no longer necessary." The production manager for aluminium components also stresses further advantages of the welding robot: "Especially in summer, in the main holiday period, our production is very busy. With the robot system we can maintain our output, even if one of the four manual welders is not available - a decisive benefit for us. Although we do not produce safetyrelevant components, each individual seam must be absolutely watertight (Fig. 7). Because of this, our qualified staff, mainly metalworkers, do not require a welding qualification. Therefore we can also employ "nonwelders" at the robot station. Here, careful and quick loading of the rotating positioner, which feeds the workpieces to the robot, is highly important.

A perfect team: EWM and Motoman

Credit for the fact that automated welding could be introduced at alwitra with justifiable investment costs is also due to welding technology advisor Markus Wagner. "We were looking for a high quality used robot system, and we found this in the form of a Motoman robot," remembers Thömmes. "Markus Wagner, the technical advisor of Gustav Westerfeld GmbH, Saarbrücken, recommended the Phoenix power source for the robot we selected. We gladly followed his advice, as in almost 20 years of cooperation we have had very good experience with his competence in welding technology and the quality of his advice."

As Thömmes explains, the company plans to continually extend the range of tasks for the robot: "At the moment we are in the course of relieving the capacity of the longitudinal welding system. In addition, we are expanding jig production for various profiles (Fig. 8). Above a quantity of more than 100 units it is worthwhile transferring the joining tasks to the robot."

Convenient to programme - characteristics from the database

Christoph Schmidt, assistant to the management and responsible for technology and maintenance, is also convinced of the efficiency of the power source/robot team. As he was jointly responsible for the investment, the electronic and programming features of the power source control were decisive for him. "The simple, almost selfexplanatory method of programming via the RC1 control panel also made our decision easier." He continues, "The preset welding characteristics of the power source are also very convenient and helpful. After simply selecting the right welding task from the database, you have very good welding results right from the start. Only a few small changes, such as the correction of the arc length and dynamics are necessary to optimise the welding program."

Optimised costs with flexible system components

In terms of unit production costs, a cost comparison in a highwage country is relatively simple: automated systems or even robots considerably reduce unit costs in comparison with manual production. In Germany, robots have been a part of small to medium sized as well as craft businesses for a long time now. Welding robots in particular are a major feature. With the automation of welding tasks, companies obtain benefits in several respects: the quality of the product and the number of units per day remain constantly high, and qualified staff can be used at key points in the company such as planning, design, work preparation and quality control. At peak production periods the robot works without surcharges and allowances for overtime.

The investment in a welding robot system is manageable. Essential components are the clamping device, the positioner, the robot and the welding power source. The robot must precisely guide the tool (torch and hose package) and the power source must be capable of excellent and reliable handling of the particular welding process. Finally, the communication between the units must function perfectly. The Phoenix MIG/MAG power source (equipped with an appropriate wire feed) from German market leader EWM provides the ideal prerequisites for smooth production using robots from all wellknown manufacturers.

- The modular equipment system is highly flexible and is orientated to future requirements. The Plug & Weld function recognises all components automatically. Integration is simple, thanks to various interfaces for program and control voltage operation, industrial bus systems (Profibus, Interbus, CAN-Bus, Devicenet) and connection of WF units.
- The control panel is only required for programming.
- Perfect ignition and welding properties with 100% reproducible results and the highest quality thanks to the digital bus system.
- High efficiency thanks to lowspatter welding of all materials.
- Long duty cycles, designed for multiple shift continuous operation.
- Easy servicing and maintenance.


Fig. 2: MAX BAHR DIY store, Hamburg: Here, the world's first electricity generating roofing sheet EVALON Solar provides 88.1 kWp (Kilowatt Peak [peak power]). Aesthetic, innovative, environmentally friendly and guaranteed watertight - planners from all over the world rely on complete roofing systems from the Rhineland Palatinate.

Fig. 3: Albert Thömmes, production manager for aluminium components (left): "Our power source/robot team does just what we demand of it - shift after shift." Christoph Schmidt: "The almost selfexplanatory programming method using the control panel made our decision for the power source easy"
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