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XYZ AC Motors vs. DC Motors for Power Presses

Nov 01, 2012

Depending on the drive style, a high-tonnage mechanical press can stamp out metal parts at up to 1,000 strokes per minute. Even so, it’s a remarkably durable machine. The steel frame will long outlive the motor and electronic controls that drive the flywheel.

And therein lies a problem. Most mechanical presses built in the 1980s or earlier were powered by DC brush motors. And they are expensive and difficult to replace, retune and maintain. A new DC motor can take weeks to get. Once installed, it must be tuned with potentiometers and jumpers. The process requires considerable tweaking, even if the original motor’s “pot” settings are known.

“We have several customers where engineers used a paint marker to note how the potentiometers were set,” says Steve Spero, service engineer with Yaskawa America Inc. “We have other customers where no one knew how they were set, and it can be all sorts of fun turning those knobs to get the motor back in working condition.”

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