Sitech Sitztechnik (Polkowice, Poland), a wholly-owned subsidiary of the Volkswagen Group, manufactures steel frames for car seats. Recently, the company, which operates plants in both Europe and China, upgraded its Polish manufacturing facilities to increase production capacity to 53,000 seats and 77,000 seat backrests per week.

Overall, the facility is divided into four production sections: backrest preassembly and final assembly; seat preassembly; and final assembly. Production lines include automatic riveting, tightening and joining stations, as well as 32 robotic welding workcells and several dozen manual assembly stations.

To move work-in-progress quickly and efficiently from point to point, Sitech Sitztechnik implemented a pallet-based TS 2plus modular transfer system from Bosch Rexroth Group (Charlotte, NC), along with a number of Bosch Rexroth electrical transverse conveyors, modular units that are used for positioning pallets, and transportation control.

In all, Sitech Sitztechnik uses more than 500 pallets measuring 640 by 640 millimeters. At the beginning of the line, the steel seat frames are manually placed on the pallets, after which they are carried on a flat-top chain to individual processing stations by three parallel conveyor sections that operate independently. At the end of the line, the pallets return to the starting point by traveling underneath the conveyor on a double belt-saving around 30 percent of the space originally planned for the system.

According to plant project manager Clemens Haller, Sitech Sitztechnik chose the system, in part, because of its flexibility and the need for a standardized system across the plant floor.

"In view of some 60 models and the linkage between different operational steps, we needed a system solution to get an ideal facility," Haller says. "A perfect interplay between transfer systems, manual workplaces and the necessary special a must. This is vital to enable us to keep to the short cycle times and ensure the quality."

Among other "special solutions," Haller says his company was able to use a number of 90-degree and 180-degree curved sections for feeding workpieces to some of the production line's welding robots. Sitech Sitztechnik was also able to improve the ergonomics of its manual assembly stations by equipping each pallet with fixturing that presents seat frames to workers on a slight angle.

Finally, the system's durability and the interchangeability of its constituent parts means it can be reconfigured down the road in response to market demand and product changes. "The great ease in converting and adapting the transfer system, and in reusing the basic mechanical elements and the manual workplaces was definitely...a significant decision criterion," Haller says.

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