Two metric tons per drive, a high-bay warehouse reaching to 30 meters in height, extremely limited space – the conditions when removing each of the four parallel-shaft helical gearmotors and replacing them at dizzying heights after as-new repair really couldn't be more challenging. However, thanks to precise planning and implementation on the part of Alfred Imhof AG, the long-goods SRS are back to being fully functional.
Further information about STOBAG AG:
As-new repair of travel drives: Four parallel-shaft helical gearmotors plus one spare drive, type FA157/G D315S4 (series 7). A gearmotor in each of the four storage/retrieval systems drives a cable drum, thereby moving the gripper.
Figure: This is what a happy project team looks like (left to right):
SEW‑EURODRIVE products are durable and very low-maintenance.
We almost exclusively use SEW drives and the corresponding electronics in our storage facilities, in assembly and on the conveyor lines. The products are durable and very low-maintenance, which ensures a high level of system availability. The support we get from Alfred Imhof AG, which installs and distributes SEW products in Switzerland, is also excellent. We don't want to use anything else.
We are pleased we can count on the full support of Alfred Imhof AG.
We are pleased we can count on the full support of Alfred Imhof AG for this challenging project. Not only has the drive specialist proven itself a dependable partner for the actual overhaul work, but it was the expertise of its staff that made the whole planning and implementation process possible in the first place. We can now plan on the assumption that the drives will give us another ten years of dependable service.
An oil leak usually indicates some kind of anomaly in the drive.
A sudden drive failure would have virtually crippled the high-bay warehouse at STOBAG and put a partial halt on production for several days. That absolutely had to be prevented.
By mid-summer at the latest, there will be few if any patios that don't feature some form of sun protection. That is why the STOBAG plant in Muri, Switzerland, has been dedicated to the manufacture of high-quality wind and weather-resistant awnings and other shading systems.
Just as people need protection from the sun, modern and efficient production at STOBAG relies heavily on an automated high-bay warehouse for storing long goods. The 30-meter-tall system was built by Trafö, which is based in Lauda-Königshofen in the German state of Baden-Württemberg. Comprising 32 aisles and a total of 1678 storage spaces for long goods, the system supplies a constant stream of parts for the production of a huge range of shading systems.
400 custom-configurable awnings – painted in virtually any color – are manufactured here every day. That makes a just-in-time production process essential, and the system must be integrated to the highest standards and offer maximum flexibility. One of the top priorities for STOBAG is providing customers with the most extensive personalization possible and the best quality standards, while also achieving optimum production efficiency.
To manufacture products to this high standard and offer an appropriate warranty, companies need system technology of the utmost quality and components that function perfectly without exception. We have been supplying STOBAG with drive technology for several years. As a result, the warehouse, assembly plant and conveyor lines run almost exclusively on drives and inverters from SEW‑EURODRIVE and benefit from the best possible support from service engineers at our Swiss agency Alfred Imhof AG.
Since their manufacture in 2005, the four parallel-shaft helical gearmotors had been working tirelessly in the long-goods high-bay warehouse at STOBAG. Each of the high-performance drives applied a high torque of up to 8430 Nm to move the grippers of its storage/retrieval system to the intended storage space and back again. It was only in 2017, after more than eleven years and several thousand operating hours, that the drives showed the first signs of wear and oil leaks. The staff in the Technical Service team at STOBAG AG immediately reported what they had found to their supplier Alfred Imhof AG.
Rainer Trumpp, the project manager for service at Alfred Imhof AG, is well aware that an oil leak has to be dealt with straight away and wasted no time. "An oil leak usually indicates some kind of anomaly in the drive. A sudden gear unit failure would have virtually crippled the high-bay warehouse at STOBAG and put a partial halt on production for several days. That absolutely had to be prevented."
Trumpp got a chance to see just how right he had been when he inspected the drives later on – oil from the gear unit had already gotten into the motor. In a case like this, the most likely cause is worn oil seals, and these ones had thousands of operating hours behind them. A vibration analysis was carried out, too, and showed that the rolling bearings had also reached the end of their rated service life.
The vibration analysis takes the form of the "Vibration SmartCheck" sensor, which is an optional accessory for gearmotors from SEW‑EURODRIVE. The frequency spectrum that is measured can be used to easily draw conclusions about the state of the rolling bearings. This continuous monitoring ensures plant operators always have their drive technology under control.
A production system that has to keep on running, gearmotors weighing two metric tons and installed at a dizzying height, no crane on site and extremely cramped conditions – it's hard to imagine how the conditions for overhauling the drives could have been much worse. Given the complexity of the situation, plant engineering firm Trafö was also very interested to see the detailed plan specially developed and ultimately put into action by the service experts at Alfred Imhof AG.
The overarching idea was revolving replacement! This solution was possible because STOBAG had a spare drive that it kept for those times when things don't go to plan. The spare would be used to replace the first of the four drives, so it was the first to be sent to Alfred Imhof AG in Münchenstein, Switzerland, for careful inspection. Once the slight defects resulting from its long period in storage had been quickly rectified, the spare drive could be fitted in place of drive one, which could then go for maintenance. When drive one had been overhauled it was used as a replacement for drive two and so on.
The as-new repair of the disassembled drives involved inspecting all the gearing and replacing the hollow shafts and bearings of the gear unit. The AC motors were de-oiled and dried. The next step was to fit new bearings and an oil seal to the motors. During final inspection, a high-voltage test and resistance measurement were carried out on all the motors.
By adopting this approach, the project team was able to carry out maintenance on all the gearmotors at different times, one after the other. At the end of the process, awning manufacturer STOBAG had a total of five gearmotors, all restored to as-new condition – four in use and one in storage as a spare. The advantage to this revolving replacement concept is that production was disrupted only to a limited extent and for a short period of time. It looks like all should be well at STOBAG for the next ten years – at least as far as these parallel-shaft helical gearmotors are concerned. The company can once again count on smooth production operations as it manufactures its huge range of shading systems.
The process on site was the same each time a drive was replaced:
Besides the overhauled parallel-shaft helical gearmotors used to raise and lower the grippers of the storage/retrieval systems, STOBAG's Muri plant also relies on other drive technology from SEW‑EURODRIVE to keep everything running smoothly – and always with the best possible support from our Swiss agency Alfred Imhof AG:
