Investing in a plastic de-flashing shot blast machine cuts the personnel requirements by nearly 50%

The Schaltbau GmbH is a globally leading supplier of direct current (DC) solutions. This multi-division company, located in Munich, specializes in electrification products and solutions for many industries. For decades railway customers have been utilizing the comprehensive portfolio of contactors, plug connections, switches and safety components. The trademark Eddicy stands for ultra-modern solutions for safe and reliable switching operations and the protection of direct current applications in the sectors energy and e-vehicles. These innovative products are produced at several locations in Germany, Europe, the United States and Asia including a plant in Aldersbach, located in Bavaria, Germany.

Reducing manufacturing costs through automation
Armin Voggenreiter, director of operations at the Aldersbach location of the Schaltbau GmbH, comments: „To remain competitive at our Aldersbach plant we work hard to identify cost reduction possibilities for practically every single manufacturing step.” As part of a lean manufacturing project the production of housing components was extensively analyzed. These are molded in a pressing operation utilizing melamine/polyester materials. Due to some material overflow in the press unwanted flashes are created, which must be removed to ensure the safe assembly and functionality of the components. To date the flash removal was done manually requiring a lot of time and personnel. For example, one person was stationed at each press. Therefore, automating the de-flashing operation offered a substantial cost-saving opportunity.
The project managers at Schaltbau presented this task to two equipment manufacturers, whose machines are already utilized in other manufacturing areas of the company. Armin Voggenreiter explains: „Rösler was one of the two suppliers we talked to. We know this company well, because it has been a reliable partner of ours in the field of mass finishing.” A major requirement for the selection of the right blast machine was that the de-flashing process had to be extremely gentle. For example, the components must not tumble over each other during the entire process, and they must be completely free of any residual blast media when coming out of the machine. „For this challenging task Rösler presented the by far most convincing equipment concept”, remembers the director of operations. Rösler offered the highly flexible wire mesh belt blast machine, model RSAB 370-T1+1, as the most suitable solution for the continuous, gentle de-flashing of the housing components. The de-flashing trials at Rösler were conducted in a comparable machine. „The excellent results of the processing trials convinced us that the Rösler equipment concept was by fare the best for our purposes”, concludes Voggenreiter.

Effective de-flashing with less personnel
After they have been pressed, the duroplast components, with dimensions of up to 350 x 215 x 45 mm and weighing up to 575 Gramm, are manually placed on the 370 mm wide, wear-resistant wire mesh belt. The transport speed through the blast machine, precisely adapted to the respective work pieces and the severity of the flashes, is stored in a processing program, which can be selected by the operator at the control panel. The blast chamber is equipped with two W32 turbines, which were specially developed for the treatment of plastic components. One turbine is placed above and the other below the wire mesh belt. The mesh is wide enough that the blast media – in the form of polyamide pellets -- reaches the work pieces on all sides so that they can be de-flashed in one single pass through machine. Any dust created during the process is continuously removed. Moreover, the standard blow-off system and the additional compressed air blow-off device ensure that any residual blast media is removed from the de-flashed components.
At the machine outlet a chute transfers the finished housing components to a separate conveyor belt system in “L” shape design for returning the components to the loading section, where they are removed by hand. „The shot blast machine allowed us to reduce our personnel costs by around 40 %“, reports Armin Voggenreiter. To minimize the operating noise, the entire shot blast machine is placed in a noise absorbing cabin. To offset the resulting shortening of the loading area, Rösler increased the length of the wire mesh belt.

Safe processing and operation in compliance with ATEX regulations
The standard, highly effective blast media cleaning system with vibratory screen and air-wash separator, augmented by the automatic media replenishment system, ensures that the blast media mix in circulation always contains the optimal pellet size distribution. The RSAB 370-T1+1 at Schaltbau also contains an anti-static system with automatic compound dosing. This practically eliminates the risk of dust and blast media adhering to the de-flashed components. The anti-static system and the installation of an ATEX compliant dust co of the safety measures required by ATEX.