Moving Coil explained

How Moving Coil Actuators work?

At the heart of all SMAC actuators is the moving coil, also described as a voice coil actuator. The essential principle is the same as you will find in any permanent magnet loudspeaker. The voice coil sits in a strong magnetic field, and by passing a current through the coil a force is generated in either direction. With SMAC actuators, the moving coil makes an ideal linear motor.

The amount of force generated is governed by the equation: F N I B

  F is the force generated
  N is the number of turns in the winding (Constant)
  I is the current flowing through the winding and
  B is the magnetic flux (Constant)

Therefore, by controlling current we can accurately control the force output.

Other voice coil acuators give no proviison for position feedback, but all SMAC actuators include a precision, non-contact linear encoder. This allows closed-loop servo control of motion in position in velocity modes and real time monitoring of position in all operating modes.

This unique features allowed SMAC to develop the Soft-Land™ routine, which has permitted applications simply not possible with other technologies.

Benefits of Moving Coil Technology

  • Lower moving mass with the voice coil actuator means extremely high acceleration and velocity, as opposed to the heavier “moving magnet” technology used in most linear motors.
  • Safe and energy efficient: operates at low current, typically at 1.5 amps at 24 volt DC.
  • Quite (< 55dB), airless operation: no expensive compressed air generation required. No air consumption or air leaks to attend to. No compressed air generating environmental particulate contamination.
  • No pressure valves, no force fluctuations caused by air pressure fluctuations.

SMAC Unique Features and Advantages

  • Fully programmable in Position, Acceleration, Velocity and Force.
  • Direct drive = no backlash, a very high degree of accuracy & repeatability.
  • Sub-micron resolution (5µm to 100nm)
  • Force control = Soft-Land capability: light force without damaging parts/material being handled.
  • >250 million cycles MTBF = long operation life

SMAC Actuators Offer Flexibility:

  • Integrated position measuring system with glass scale and optical reader head (no contact wear).
  • Ability to switch between operations - force, position and velocity mode - at any time.
  • “On the fly” adjustable movement allows quick changeover.
  • Constant force monitoring and control.
  • Digital and analog input/output channels.
  • SMAC linear motors are a servo system, hence can be programmed to decelerate smoothly and quickly. Mechanical slamming can be totally eliminated.
  • Competitively priced electric actuators that offer all above features and benefits.


For more information please contact us


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