Magnetics Business & Technology - May/June 2020 - 14

FEATURE ARTICLE

Using New Magnet Materials & Electromagnetic Designs, Electric Actuators Are Rapidly
Replacing Hydraulics
a relatively simple but widely used component in aerospace systems. Many of those applications are
critical to the safe operation of the aircraft and proper function literally can
mean the difference between life and
death. Every ball joint used in a critical mechanism absolutely must operate smoothly and reliably with minimal lash and articulation resistance
within very tight specifications.

In the Air and on the Ground, the Future Is Electric
By Glenn Nausley, President, Promess, Inc.
Hydraulics have been the technology of choice for aerospace
actuators almost as long as the industry has been in existence,
but that's now changing very rapidly. The trend today is strongly
toward replacing hydraulics with advanced electric actuators utilizing new permanent magnet materials and sophisticated electromagnetic designs.
The primary driver is weight. Hydraulics are very power dense at
the point of application, but the fluids, pumps,
motors, piping, valves and actuators make the
overall system heavy. In an industry where every pound can represent thousands of dollars
in annual fuel cost the weight-saving benefits
of today's electric actuator technology are
compelling. For example, it's been reported
that American Airlines saved $1.2 million annually simply by replacing a 35-pound paper
manual with an iPad.
Glenn Nausley
Another, not so obvious benefit of electric actuators is that they easily can be configured
to generate both power and real-time data that can be used for
control, diagnostics and performance analysis. As modern aircraft
increasingly utilize "fly-by-wire" technologies that integrate human
and computer controls, feedback data from electric actuators provides essential system inputs to close the loop.
Given the clear advantages of electric actuators in many aircrafts
and aerospace applications, it's only a matter of time until the
technology used to control aircraft migrates into the systems used
to build aircrafts. Here again, hydraulic applications still dominate
many manufacturing and assembly processes, but electric technologies are challenging that dominance with a set of compelling
benefits.
As an example, let's look at the process for assembling ball joints,

Magnetics Business & Technology * May/June 2020

The traditional ball joint manufacturing process uses a hydraulic press
to form the cup around the ball. The
product is then tested to determine if
it meets functional specifications. As- Ball joint assembly
semblies that fail are scrapped, wasting costly materials, labor, time and
money. It's not a very efficient system, but it's the only one available to manufacturers using the traditional hydraulic press- based
assembly process.
Replacing the hydraulic press with an electrical actuator, however, creates a system that produces ball joints with virtually identical functional characteristics and almost no scrap. By combining
the control and decision-making power of modern computers and
software with the precision of servo-controlled electromechanical
devices, such a system can measure and adjust the functional
characteristics of a ball joint while it's being assembled.
Lash and articulation resistance are determined primarily by the fit
between the ball and cup which can be tested by articulating the
ball while the joint is being assembled and monitoring the values.
This is done easily with a pair of servo-controlled devices, an instrumented electromechanical press and an instrumented torque
application and measurement system controlled and monitored by
a computer running analytical software.
My company has built a number of ball joint assembly systems using our Servo Press (EMAP), shown in photo at top, TorquePRO
and UltraPRO multi-axis controller.
The Servo Press (EMAP) is a press
consisting of a ballscrew driven by a
servomotor and equipped with an array of sensors to measure position,
force, and any number of other process parameters. The TorquePRO
combines a servo motor and torque
transducer in an integrated torque
spindle package that delivers plug
and run functionality. The UltraPRO
is a very powerful multi-axis controller running both servo-control and Torque assembly
patented force/position signature
analysis software.
Once the parts are loaded the EMAP moves down to the preprogrammed initial engagement point and the onboard sensors

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Magnetics Business & Technology - May/June 2020

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