When BMW (Munich, Germany) gave the go-ahead for development and production of the new 3 Series, a more powerful and flexible assembly system would have to replace the company's then current production methods. The demands placed on the new assembly system were high. It had to link manual workstations with automated production and guarantee maximum productivity.

After investigating transfer systems, the facility planners chose the MTS 2 modular transfer system from Bosch Automation Technology (Buchanan, MI). Assembly equipment for the manual workstations was also inte-grated smoothly into the new assembly system.

The MTS 2 links 13 station modules, of which 10 stations are designed for manual work. Sixty workpiece pal- lets, 30 for the left-hand grill and 30 for the right-hand, travel through the assembly system. The pallets are equipped with a data tag that records the entire routing plan. The data tag ensures that the workpiece automa-tically takes the proper path within the transfer system and stops only at the station in which the next assem- bly step is scheduled.

Each fresh-air grill consists of 36 individual parts. Eight manual stations were provided in the production line for the louvers. At stations one through four, two identically equipped workstations mount the vertical louvers for the left- and right-hand grills. Corresponding X pallet distribution--one of the basic functions of the MTS 2--ensures uniform loading of the parallel workstations.

Horizontal louver assembly is performed at four manual workstations. Assembling the components, which are coated with special water-based paints, requires dexterity. After a worker inserts the louvers into an assembly apparatus, they are snapped into place with a connecting rod and covered with the upper part of the housing.

Prior to processing, each worker checks that the arriving workpiece is complete. Improperly assembled workpieces are sent back for repair. The MTS 2 controller ensures that the workpiece pallet is returned to the specific station responsible for that error.

The fully assembled halves of the housing, still loosely stacked, continue in the transfer system. At the next two automated stations, two ultrasonic welding machines permanently join the upper and lower halves before imprinting.

The imprinting of all fresh-air grills by a stamp-print process occurs at a common station. Using a specially designed workpiece pallet allows centering the print head and printing the left- and right-hand grills simultaneously. A light barrier at the station entrance generates the signal to load the print head with fresh paint prior to each printing operation. A warm-air blower dries the paint, and the grills leave the station at 7-second intervals.

The left- or right-hand grill proceeds to final assembly via the corresponding outfeed module. The air flap and bevel gear are mounted. After a successful final check, two seals are mounted, and the grills are placed into a sectioned container.

For more information on con- veyor systems, call Bosch Automation Technology at 800-322-6724, visit www.bosch.com.