STOBAG AG Switzerland: As-new repair in high-bay warehouse
Working at dizzying heights while production continues
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.
Plant manufacturer: Trafö-Förderanlagen GmbH & Co. KG in Lauda-Königshofen (Baden-Württemberg), Germany
Location: Muri (Aargau), Switzerland
Industry: Shading systems
Application: Storage/retrieval system for high-bay warehouse
Further information about STOBAG AG:
1964: The company is founded by Ernst Gremaud in an old must cellar in Langnau-Gattikon.
The company name comes from "STOren-BAu Gattikon" (Gattikon blind construction).
From 1968: The company starts to export components for awnings and roller blinds.
Patented telescopic arm technology for large awnings.
Subsidiaries in Italy, Austria, Brazil and the Netherlands
From 1988: Expansion of the site in Muri
2012: Awning production plant goes into operation
The sun and weather protection systems for terraces and balconies are custom-made in terms of frame color (the aluminum parts are powder coated in RAL/NCS colors) and cover design.
Maximum customization to the highest quality standards
High system availability
Just-in-time production process
Avoidance of production downtime
Durable drives (the old parallel-shaft helical gearmotors are twelve years old and have been driving the cable drums used to move the storage/retrieval system grippers without any trouble)
Following an oil leak, preventive maintenance was requested for the drives to avoid extended downtime
All four gearmotors had to be overhauled without interrupting operations
Extremely tight space for removing drives
No crane available on site to move gearmotors weighing two metric tons
Existing spare drive to be used
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.
Vibration analysis revealed that the rolling bearings had to be replaced
Detailed planning of the service project
Temporary installation of a ceiling-mounted crane for handling the 2-metric-ton drives
The drives are removed in the tightest of spaces, the gear unit and motor are lowered separately from a height of 11 meters and are then replaced in reverse order after being repaired
Revolving replacement principle: The four parallel-shaft helical gearmotors are repaired one after the other at different times so as to minimize disruption to ongoing production operations
As-new repair process in summary:
Check gearing, hollow shaft and gear unit bearings
De-oil and dry motor
Replace oil seal
Perform final inspection with high voltage testing and resistance measurement
Drive technology from SEW‑EURODRIVE installed in the high-bay warehouse for long goods:
Lifting drives (as-new repair): Parallel-shaft helical gearmotors with manual brake release, brake and incremental encoder
Travel drives: Helical-bevel gearmotors
MOVIDRIVE®B application inverter for controlling the travel drive and lifting drive
MOVIDRIVE®MDR regenerative power supply used to feed the energy recovered from the lowering and braking motions back into the power grid
Smooth-running, durable and low-maintenance drives
Following their as-new repair, the drives will be able to run smoothly for another ten years
Repairing the units at different times minimized the disruption to production operations
A dependable partnership with Alfred Imhof AG
High system availability
Reliable and rapid support
Regenerative power supply saves energy
Figure: This is what a happy project team looks like (left to right):
David Brunner and Urs Koch, Technical Service at STOBAG AG
Ralf Haas, head of procurement at Trafö-Förderanlagen
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.
Quote from Urs Koch, Technical Service at STOBAG AG
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.
Quote from Rainer Trumpp, project manager in the Service department of Alfred Imhof AG
An oil leak usually indicates some kind of anomaly in the drive.
A home for long goods: 4 storage/retrieval systems, 32 aisles, 1678 storage spaces
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.
The first oil leak after thousands of operating hours
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.
Revolving replacement principle: Step-by-step overhaul without shutting down the system.
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:
A ceiling-mounted crane consisting of a steel beam and two crane trolleys (fitted with chain hoists) was temporarily suspended from a ceiling joist.
The AC motor and parallel-shaft helical gear unit were separated on site and in situ due to their significant weight and unfavorable center of gravity. To do this, the motor was first connected to the crane and only then was the flange disengaged. To release the gearing, the motor had to be tilted slightly. That was the only way to remove it from the gear unit.
Once removed, the motor was pulled back along the crane rails to the platform, from where it was lowered the eleven meters to the ground using a cable winch.
The next step was to attach the gear unit to the ceiling-mounted crane. Once secured, the fixings connecting the gear unit to the steel beam of the SRS could be loosened slightly and the unit then pulled off the shaft.
The gear unit – suspended from the traction cables like the motor before it – could then be moved along the rails and lowered to the ground with the cable winch.
The spare drive was also refitted to the system in two parts and reconnected to the cable drum of the rack in the reverse sequence.
Other equipment from SEW‑EURODRIVE in the plant
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:
The travel function of the four long-goods storage/retrieval systems is driven by helical-bevel gearmotors
MOVIDRIVE® B application inverters act as the brain of the high-bay warehouse, controlling the travel and lifting drives and thus coordinating the hovering and dynamic movements of the SRS.
The MOVIDRIVE® MDR regenerative power supply ensures the energy recovered from lowering and braking motions can be fed back into the power grid.