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Hydraulic to Electric Conversion: The Time is NOW!

For decades, affordable motion control solutions using hydraulics have been a staple in factory automation.

Rugged and relatively low cost to deploy, the advantages of hydraulic solutions couldn’t be ignored. Electric solutions have played a part for a while, but the advantages of hydraulics were often too difficult to beat.

However, recent advances in electromechanical solutions — specifically, high force roller screw actuators and electric servo controls — are providing electric alternatives that challenge hydraulics’ position in the automation marketplace.

What is an Electromechanical System in Factory Automation?

Electromechanical means “something that moves but has no fluid — only electricity for power”.

A motor goes round and round, but the motion needed is back and forth. This is what ball screws, rack pinions, and belts are used for — converting electrical rotary motion into mechanical linear motion.

All discrete manufacturing uses electromechanical automation. Food manufacturing, packaging, machining, welding, automation, and automotive industries commonly use electromechanical solutions. Robotics, something your operation may already be actively using, are one example of electromechanical solutions; they move and are powered only by electricity.

Parker Belt Drive Actuator

A Parker horizontal belt drive actuator is used for transferring parts from one conveyor to another or removing finished parts from an assembly dial. Robots are electromechanical devices as they move by being powered only by electricity. 



Emerging Benefits of Electric vs. Hydraulic

1. New, High Force Capacity

Ball screw electric actuators have been an automation solution for up to 10,000 pound-force (lbf) (44.5 kN) thrust applications. At such a low force, this limited the application overlap with hydraulic solutions.

However, new roller screw actuators deliver thrust force capacity up to 250,000 lbf (1112 kN), allowing electric solution designs where only hydraulics played before. Advances in servo motor/drive technology allow for stock drive capacities of 55 kW (73 Hp).

These high force actuators can now be electrically driven as the needed electric servo motor/drive power is readily available.


2. Advanced Motion Control

Positioning improvements of 10X are regularly achieved when converting to electromechanical solutions.

Electric motion control provides complete Position / Velocity / Force control of the actuator. Actuators move to different positions on command and can have different acceleration and decelerated profiles. While hydraulics only have one profile for any valve setting, electromechanical solutions have servo control, which allows every move to have a different acceleration / deceleration / velocity / destination.

These motion features with high force actuators are providing automation engineers tools that were previously beyond their grasp in the hydraulic world. Enhanced precision and repeatability in both position and velocity are additional benefits that are inherent in these electromechanical solutions.


3. Environmental Cleanliness

With no hoses to leak, no filters to change, and no hydraulic power unit (HPU) heat to disperse, electromechanical systems are a clean and environmentally friendly solution


4. Lower Cost of Ownership 

Hydraulic solutions are subject to performance changes with temperature as the fluid changes when cold vs. hot. Additionally, hot hydraulic fluid is hard on seals and hoses leading to extra maintenance on the system.

To counteract fluid heating, HPUs integrate fluid coolers adding operation cost and additional required space. Electromechanical solutions do not have response differences with changing environments. Electric servo motors respond the same in all operating temperatures.

Electromechanical efficiency is above 80% vs. 40-50% for hydraulics systems.

These factors lead to hydraulics having a higher cost of ownership when compared to electromechanical systems.


5. System Simplicity & Smaller Footprint 

Hydraulic systems generally have a smaller filler load point than an electromechanical solution.

However, when considering the total space required for the HPU, the electrical systems are considerably smaller. The electromechanical solutions have much fewer parts in the system. And the maintenance on electromechanical systems is incredibly low compared with a hydraulic system.



Major Advantages of Electromechanical Systems

Simply put, electromechanical systems will provide the following advantages over hydraulic systems:

  • 80+% efficiency 

  • High precision + high force

  • Consistent performance - regardless of temperature

  • Easy motion integration with PLCs 

  • Infinite positioning capability

  • Instant reaction time

  • Clean & quiet

  • Environmentally friendly

  • Low operation cost

  • Low maintenance 



Advantages of Hydraulic Systems

While electromechanical systems are an emerging trend with many benefits, hydraulic still reigns supreme in some applications: 

  • Up to 400 tons of force available from hydraulic systems; 250 tons of force from electromechanical.

  • Cylinders generally smaller for given force/stroke requirement.

  • Lower cost if simple, high force need.

  • Higher shock load capability.

  • Very rugged and relatively simple.

While hydraulic solutions were once the most accessible, beneficial component, technology has grown.

There are many more applications that can benefit from electrification due to the expanding capability of electromechanical solutions.

Interested in our electromechanical solutions? Connect with an MCE representative today!



About the Author: Bill Johnson is the Chief Technical Officer for RSA Solutions.

Bill has been providing advanced motion solutions to the automation marketplace for 37 years. He has a BSME from Rose-Hulman Institute of Technology.


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