The goal was maximum efficiency in all areas. To achieve this, a German manufacturer of drive and maneuvering systems, as well as complete control systems for ships and offshore applications, invested in the roller conveyor blasting system RRB 22/5 from Rösler. The system, optimally integrated into the production process, enables the semi-automated processing of various flame-cut parts and steel sheets. It largely replaces the previously conducted manual blasting.
It was the groundbreaking invention of the fully controllable rudder propeller in 1950 that laid the foundation for the impressive success story of SCHOTTEL GmbH. The innovation quickly made the company, founded in 1921, a sought-after developer and manufacturer of ship propulsion systems worldwide. With nine series covering a power range from 50 to 30,000 kW, the largest portfolio of propulsion and control systems for ships and offshore applications of all kinds and sizes is now offered.
In addition, comprehensive marine services are provided: intelligent solutions for remote access, data collection, data analysis, condition monitoring, and predictive maintenance. Production takes place at the German locations in Dörth and Wismar. The combination of years of propulsion experience with powerful hardware and software, as well as current scientific findings, ensures that all products meet the latest technological standards and a high level of quality.
Efficiency increase through automation, flexibility, and ensuring higher availability
Continuous investment is also made in production. In the welding shop at the Dörth plant, manufacturing processes have been made more efficient and capable through the integration of a sheet metal line. This included the integration of a sheet metal automatic storage system and a plasma/oxy-fuel cutting system, as well as the conversion of the blasting process from cabin blasting to through-blasting. To minimize both personnel effort and intralogistics, the new roller conveyor blasting system was placed directly behind the cutting system – in line. One of the essential processing requirements was that the blasted surfaces must have a roughness depth of at least Rz 70 µm. This must be achieved to ensure the necessary adhesion strength of the paint required for maritime applications during subsequent painting. Therefore, SCHOTTEL used an angular, abrasive blasting medium for cabin blasting to ensure the required quality. Furthermore, the new blasting system should enable the processing of parts with very different dimensions and ensure high availability.
Well-thought-out system concept with high capability and flexibility
In search of a suitable blasting system manufacturer, Frank Steinert, production manager at SCHOTTEL, contacted Rösler Oberflächentechnik GmbH, among others. The Untermerzbacher plant manufacturer designed a solution adapted to the customer's requirements based on the standard roller conveyor system RRB 22/5, including special coating. This allows processing of steel plates up to five meters long, up to two meters wide, and a maximum height of 500 mm. At the same time, the roller conveyor with a roller spacing of 400 mm allows blasting of individual parts with a minimum length of 1,500 mm. With the use of an additional transport frame, massive parts smaller than 1,500 mm can also be processed.
As a result, a large proportion of the flame-cut parts used in SCHOTTEL's end product can be manufactured much more efficiently. The respective blasting program stored in the system control can be comfortably selected by the operator at the touch panel.
The system is made of eight millimeter thick manganese steel as standard, and additionally, the blasting chamber contains replaceable, overlapping plates made of the most wear-resistant material. Six high-performance turbines Gamma 400G, each with 15 kW drive power, ensure consistently good blasting results – three blasting from above and three from below on the parts. They feature Y-design throwing blades and achieve up to 20 percent higher blasting performance compared to conventional turbines while simultaneously reducing energy consumption.
Furthermore, the Y-shaped throwing blades can be used from both sides, which at least doubles their service life. The change can be done easily and with the turbine installed using a quick-change system. Another advantage is the filter unit placed on the roof of the system, which does not require additional floor space. 'The system and equipment concept appealed to us. However, before making a final decision, we wanted to know if our requirements would also be met,' reports Frank Steinert.
Blasting tests under real production conditions
Accordingly, blasting tests were conducted with various parts from SCHOTTEL. In this case, they were not conducted at Rösler's Customer Experience Center but could be carried out at a Rösler customer who has been using a nearly identical system with identical turbine equipment for about three years. The tests demonstrated not only that the required blasting result is reliably achieved – but also with a system-friendly, round blasting grain. The parts blasted at the reference customer were measured and evaluated.
'To be on the safe side, we also subjected the test parts to adhesion and salt spray tests internally,' adds the production manager. The open discussions that Frank Steinert was able to have with the reference customer regarding operating costs, wear behavior, and maintenance frequency were also decisive in the decision for the RRB 22/5. 'The results of the blasting tests and the experiences of the reference customer ultimately convinced us that the RRB 22/5 is the right solution for us and meets our quality requirements,' explains Frank Steinert.
Optimal integration for easier and more comfortable maintenance
The early involvement of the system manufacturer in the planning at SCHOTTEL also proved to be an advantage. As a result, information and layouts were available early on regarding what size relationships should be considered for the system and how it could be optimally planned into the hall. This resulted in the foundation for the blasting system being not only easier to create but also providing more space and thus comfort for maintenance personnel.
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