Page 39 - MetalForming January/February 2022

Where
Servo-Electric
Presses Fit
How does a servo-electric press work, and when does it make sense—or not—over hydraulic and mechanical presses?
BY LOUIS A. KREN, SENIOR EDITOR
Much has been written on the anatomy and characteristics of servo-driven presses— most commonly for servomechanical presses, a little less for servohydraulic models and not much at all for servo- electric presses. To add to the servo- electric knowledge base, MetalForming quizzed Josh Dixon, a Beckwood Press Co. veteran and recently named chief operating officer for the St. Louis, MO- based provider of hydraulic and electric press systems, including servo models and custom configurations.
MetalForming: How is a servo-elec- tric press put together, and how does it work?
Josh Dixon: From an anatomy standpoint, a servo-electric press fea- tures a similar structure to that of a hydraulic press. In place of a hydraulic cylinder for generating force, a servo- electric press employs a roller-screw electromechanical actuator—a mechanical actuator driven by a servo motor. The servo motor replaces the motors, valves, pumps and related components typically found in hydraulic presses with an electric and mechanical drive train.
MF: How does this replacement affect per- formance?
JD: A servo-electric
press features much
tighter position and force
control than can be
achieved with a hydraulic
press, offering program-
mable positional accura-
cy of ±0.0005 in. And,
while mechanical presses
excel at achieving the
same position at the bot-
tom of the stroke cycle- after-cycle, they don’t
allow for a level of pro- grammability where users can easily change it from tool-to-tool or part-to- part. Servo-electric presses maintain many of the same benefits of hydraulic presses, such as full tonnage through- out the stroke, extended dwell and pro- grammable cycle profiles.
A servo-electric press also eliminates the need for hydraulic fluid. From a maintenance perspective, or a desire to move away from fossil fuels, or perhaps an application where hydraulic oil can contaminate a product (food-grade applications, for example), elimination
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MetalForming/January-February 2022 37
Just like their servomechanical and servohydraulic coun- terparts, servo-electric presses offer the ability to program and store jobs, and control production.
of hydraulic fluid nets a positive. Energy efficiency provides another big benefit, along with noise reduction. And again, maintenance-wise, users of servo-electric presses need not chase down leaks, faulty valves and deterio- rating pumps. Servo-electric systems use far fewer components than com- parable hydraulic systems, which means less maintenance over time and
simplified maintenance overall.
MF: Conversely, when are servo- electric presses not the ideal options? JD: In some applications, hydraulic
This chart provides a comparison of servo- electric presses with mechanical and hydraulic presses. Advantages are many depending on the application.