The quality movement and lean manufacturing grew up together for good reason—they are complimentary. “Generally speaking, simpler is better,” explains Randy Wire, general manager at Evana Automation Specialists (www.evana-online.com), a systems integrator and custom builder of assembly lines in Evansville, Ind. This rule of thumb for lean manufacturing applies equally well to quality control as it does to process monitoring and other aspects of production.
“The more complex that the in-process monitoring system is,” Wire notes, “the more maintenance, calibration, verification of accuracy, and in-house expertise will be needed to support it.” For this reason, he recommends using the simplest sensor possible if all you need to do is detect the presence or fit of a part. He also suggests in-process gages wherever possible to measure parts on line to avoid the extra handling that goes with measuring them elsewhere.
Applying this strategy of simplicity paid handsome dividends in other ways on a 21-station lean manufacturing cell that Evana designed and built for Detroit-based American Axle and Manufacturing Inc. The cell produces and tests electronic actuators for automobile transmissions (see main story for details on the quality control strategy used in the cell).
American Axle’s engineers had originally envisioned a conventional conveyor-based system that moved pallets of product between automated and semi-automated stations that used automatic parts feeders and human operators. RFID tracking of process status on the pallet so each station new the results of the operation from the previous station. “The drawbacks to such a system were cost and complexity,” says Wire.
To reduce cost and improve reliability, his engineers applied lean manufacturing principles to focus on eliminating systems that did not add value. In the end, they proposed a simpler cellular concept that not only reduced the number of operators, but also eliminated most of the conveyors, pallets, RFID tracking, and parts feeders. Wire estimates that the lean concept eliminated 25 percent of the components and software in the conventional design. “That resulted in a 25 percent reduction in the number of things that could go wrong or would require maintenance for sustaining production,” he says.
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