Due to continuously growing demand for its products a globally leading supplier of iron castings had to increase its shot blasting capacity. At the same time, the new shot blast machine was intended to improve overall product quality and streamline the production flow. The company chose the Rösler wire mesh belt blast machine RDGE 1250/300-8, because it offered a custom-engineered solution and because of the customer’s positive experience with Rösler from previous projects.
The Gienanth GmbH, located in Eisenberg in the German Palatinate area, has a long history that reaches back to the 15th century. This history has been characterized by tradition, comprehensive knowhow and innovation in the field of cast iron components. Today, Gienanth produces its products at four locations in Germany, Austria and the Czech Republic. Besides engine blocks for large engines, utilized in ships, railways and generators, the company also produces components for all kinds of machinery as well as parts for the automotive and utility vehicle industry. This cast iron specialist considers himself as a solutions provider, who supports the customers along the entire value-added chain covering the generation of ideas, product development, material selection and production of the ready-to-mount components. With this integral approach the company has experienced a continuously growing worldwide demand for its products. It was also the reason for Gienanth receiving the German Innovation Award 2019 for the bionic re-design of the carrier plate for the brake pads in utility vehicles.
High technical standards and difficult installation conditions
Due to a steadily growing demand for the cast iron products the existing shot blast machines could no longer handle the higher production volume. Jens Eckel, project engineer at Gienanth in Eisenberg, summarizes the technical requirements as follows: „With the new shot blast machine we intended not only to increase our capacity, but we also wanted to make the shot blasting operation more efficient and improve the overall quality.“ To achieve an acceptable uptime of the critical machine components the equipment design had also to take into consideration the highly aggressive, angular and extremely hard blast media and the fact that every hour around 200 kg of sand are carried into the shot blast machine. Another challenge was the building, where the shot blast machine had to be placed: Because of the sawtooth roof with its complex support structure the overall machine height had to be reduced by installing a split elevator.
Custom-engineered wire mesh belt blast machine in particularly robust design
"Rösler was willing to customize the wire mesh belt blast machine RDGE 1250/300-8 exactly to our technical requirements. Of course, another important factor in our decision for Rösler was the excellent experience we had with this supplier through previous equipment projects”, reports Jens Eckel. To adequately deal with the extremely harsh operating conditions for de-sanding and cleaning, the shot blast machine was equipped with eight high-performance Rutten Gamma 330-HD turbines, each with an installed power of 18.5 kW. The machine handles a blast media throughput of up to 2,520 kg per minute. The eight blast turbines are equipped with six throwing blades in the innovative “Y” design. Compared to conventional turbines this special blade geometry generates an up to 20% higher shot blast performance with a lower energy consumption. Another significant advantage of the “Y” blades is that both blade sides can be utilized by simply turning them around. For optimal shot blast results four turbines are placed in the roof and the other four turbines are located in the bottom of the blast chamber. The special requirements of the customer were a key factor for the particular placement of the turbines: To prevent the smaller work pieces, weighing only 1.0 to 1.5 kg, from changing their position, moving on top of each other or getting blown off the wire mesh belt, the turbines are mounted at a slight angle. This allows the blast patterns of the upper and lower blast turbines to meet precisely at the wire mesh belt so that the blast stream from the upper turbines holds the work pieces in place. At the same time, the somewhat higher blast performance of the lower turbines causes the work pieces to get slightly lifted from the belt. This eliminates the risk of shadowing.
Fully automatic shot blasting operation that is fully integrated into the manufacturing flow
A vibratory conveyor transports the raw castings directly from the casting cell to the shot blast machine. This vibratory movement already removes some of the sand from the castings. At the inlet section of the shot blast machine the work pieces are transferred onto the 1,250 mm wide wire mesh belt. An employee makes sure that the work pieces are evenly distributed on the belt. After the shot blasting operation the castings are transferred to a 15 m long transport system that was also supplied by Rösler. This special foundry conveyor, equipped with a particularly robust transport belt, transports the finished castings directly to the shipping department.
Blast media recycling and cleaning system with a high cleaning efficiency
The blast media recycling and cleaning system was also designed for optimal wear protection. The media/sand mixture is initially passing over vibratory screening conveyors placed below the shot blast machine. This allows discharging larger chunks of sand as well as residual scale and slag from the system. Subsequently, the mix is transported to a magnetic separator. There a finely tuned guide system distributes the media/sand blend over the entire width of the magnetic drums, thus generating a very thin curtain of media and sand. This precise curtain, in combination with the extensive magnetic force of the high performance magnets built into the drums, produces a cleaning efficiency of up to 99.8 percent. Dosing of the blast media also takes place automatically. For this purpose the media hopper is equipped with a level sensor. As soon as the media level falls below a pre-defined value, small media quantities are added to the system through a special media replenisher. This approach ensures a highly homogeneous media operating mix and guarantees consistent shot blasting results.