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Suppliers complement their cam- and servodriven systems with newer technologies like direct-drive indexers and precision-link conveyors.
BMW performs a lot of welding operations at its assembly plants, which are located throughout Europe and in South Carolina. Recently, the automaker hired The EDAG Group to develop a small-lot welding system for a European plant.
During system development, Manfred Hahl, managing director and COO of EDAG, researched several rotary indexing tables, but learned that none were strong enough to bear 16 tons. So he reached out to automation specialist Weiss GmbH.
Weiss agreed to make a customized table based on the company's servodriven CR 2600 series. Developed within six months, the table has a 20-ton capacity. Its center opening is 2 meters in diameter, which is large enough to accommodate a welding robot with a 2.5-meter reach.
On the outer edge are four tooling sections, each of which weighs up to 4 tons and holds parts as they are welded. BMW uses two of the tooling sections to weld rear hatches and hoods.
Foerster Systems, a Salem, OH-based integrator, also likes servodriven indexers. A couple years ago, the company designed a system that inspects cross holes formed in forged steel components. The system inspects 17 part sizes. It features an EZ Indexer from Centricity Corp.
The indexer transports components 45 degrees in 0.5 second, with a positioning accuracy of ±30 arcseconds. Parts also receive eddy current testing to determine material hardness. The indexer's compact design enabled tooling to be installed under the dial plate.
These two installations represent the growing popularity of servodriven indexers, which offer greater programming flexibility than traditional cam-driven units. In recent years, suppliers have also introduced directdrive rotary indexers, precision-link conveyors and flexible linear assembly systems. All of these innovations provide manufacturers with automated indexing systems that are reliable and repeatable.
Linear vs. Rotary
Choosing between linear and rotary indexers for an automated assembly application depends primarily on space availability on the plant floor. Most products assembled on rotary indexers are small, with each assembly process taking seconds, not minutes. Indexers typically range in size from 18 inches to 15 feet in diameter.
Assembly operations performed on indexers include pick-and-place, screwdriving, dispensing, crimping, pressing and ultrasonic welding. SCARA robots, machine-vision systems and...