Linear electric actuators

Linear electric actuators

April 2, 2021

SMAC Moving Coil Actuators

Many users of pneumatic cylinders are looking for electric actuator alternatives for a number of reasons:

  • On the fly ability to change speed, stroke, force.
  • Higher cycle rates
  • Longer cycle life
  • Ability to feed back in real time what happened when work was done
  • Elimination of pneumatic infrastructure (Compressor, tank, dryer, etc.).
  • Energy savings
  • Noise reduction

Up to now this need has been difficult to fill. First off is cost, pneumatic cylinder/valve/flow control/position switch sets cost somewhere around $150. Even low cost stepper ball screw actuators cost more and only provide the programmable speed and stroke capability. Cycle life is the same and speeds are usually slower.

Linear motor driven actuators are technically much better, and moving coil type linear motors have the highest cycle rate and cycle life: >2x faster than air cylinders with cycle life 10x longer. They offer programmable speed, position, and force. They also have the ability to report back in real time how the work was done. They inherently have non rotating shafts.

The drawback has always been the cost; 5x-to-10x higher than pneumatic systems.

That has changed.

The SMAC LDL actuator has a number of very innovative cost reduction elements that result in a list price of $300 for a 25mm stroke unit, $350 for 50mm. These include:

  • Printed Coil technology with integrated SMAC encoder reader head. Effective investment make this is zero
  • Laser-cut parts resulting in housing and end cap process times in the 5sec.-to-30 sec. range
  • 1-piece, multi-pole, neodymium magnets
  • Precision linear guide life tested to 500M cycles
  • Automatic assembly, including smart screw driving, done using SMAC’s own products
  • SMAC’s built in VLC (very low cost) controller amplifier offered with various communication protocols

Early wins over the world’s leading pneumatic equipment makers resulted from the following performance edges:

  • Cycle rate of 10cps vs. pneumatic cylinders limited to 5cps (slamming of the air cylinder piston causes premature leak)
  • Non-rotating shaft eliminated the need for a guide shaft on the air cylinder which caused premature cycle failure
  • Programmable on the fly movement profile change made the machine process flexible and virtually eliminated set up time

The LDL is now offered in 12mm and 25mm widths. Other standard sizes are being added and the use of laser cutting technology also results in quick development of special shapes.