This Technical Bulletin illustrates the differences and relative advantages of Kyntronics SMART Hydraulic Actuators (SHAs) compared with Electro-Mechanical Ball Screw and Roller Screw type Actuators (EMAs).
Recently, new electro-hydraulic actuation technology developed by Kyntronics combines the advantages of hydraulic power with the advantages of servo-control resulting in an “all-in-one” actuator that outperforms alternative approaches including EMAs. It is generally recognized that hydraulic technology provides the highest amount of force output per unit of space envelope. This is often referred to as “force-density.” EMA technology used in roller screw and ball screw actuators are presented as having advantages compared with hydraulic cylinder actuators. This technology is presented as an alternative to hydraulic cylinder actuators although there are a number of shortcomings to using EMAs in applications that have traditionally used hydraulic cylinders.
The Kyntronics SHA is a complete actuation system that combines the power of a hydraulic cylinder with the precision of servo control. The SHA eliminates many of the inherent disadvantages that traditional hydraulic cylinder actuators and ball screw / roller screw actuators have.
Both the Kyntronics SHA and alternative EMA technologies incorporate servo motors and drive/motion controllers. The primary difference between SHA and EMA technology is that the SHA uses an integral hydraulic pump and cylinder to move the load, while the EMA uses a gearbox and mechanical screw / ballnut system to move the load.
Kyntronics SMART Hydraulic Actuator (SHA) System
Often referred to as an “Electro-Hydraulic Actuator” (EHA), the Kyntronics SHA is a drop-in, All-in-One solution. After simple mounting and hook-up of electrical connections, the SMART SHA is ready to operate. The actuator's efficient method of converting electrical power to mechanical force results in a smaller, cost-effective package and it’s “power on demand” feature provides significant energy savings.
SMART Hydraulic Actuator (SHA) vs. Electro-Mechanical Ball Screw/Roller Screw Actuator - Technology Comparison
Ball Screw / Roller
Screw Actuator (EMA)
|Feature / Benefit|
|High Force Density / Small Footprint||Hydraulic technology provides the maximum force density compared with Roller Screw and Ball Screw Technology allowing for a smaller space envelope.|
|Precise control of high speed, high force and position||Both the SHA and EMA actuators incorporate servo technology which provides excellent motion control capabilities. Force control is inexpensive with the SHA whereas an EMA requires an expensive load cell.|
|Backdriving||The SHA locks in place when power is removed. EMAs on the other hand are capable of being back-driven and require a brake to hold position which adds cost.|
|Energy Efficiency||Hydraulic technology eliminates metal-to-metal contact points reducing friction compared with EMA technology which has many contact points, gear friction etc. In addition, EMAs often require “pre-loading” to reduce backlash which consumes energy that is not transferred to moving the load.|
|Modularity/Flexibility||The SHA design incorporates a modular building block approach resulting in a product range from 500 Lbs (2,225 N) to 170,000 Lbs (755kN) of force, and up to 120 inches (3,048 mm) of stroke. In addition, the SHA’s Power Unit can be oriented in any direction. This compact hydraulic actuator makes it very flexible and able to fit into applications whereas an EMA is limited in its orientation flexibility due to the mechanical coupling of it’s motor/gearbox/screw components.|
|Ability to sustain “shock loading” conditions||The hydraulics in the SHA are designed to absorb “shock loads” in contrast with an EMA which can incur significant screw and drive train wear from shock loads.|
|Cost Effective / Lower Equipment Cost||Ball Screw / Roller Screw EMAs are inherently more expensive the SHAs particularly in higher-force applications.|
|Reliability / Maintenance||The SHA is a sealed system and does not require maintenance other than a rod seal change after tens of millions of inches of travel regardless of load. Comparably-sized EMAs will last a fraction of the time and require frequent lubrication. Localized thread wear on EMAs can be significant if the load is uneven over the length of travel.|
|Simple Fieldbus Control Connectivity, IoT integration||Both SHA and EMA actuation technologies can be integrated into Field-Bus control architectures and can provide IoT data collection interfaces.|
Recent innovations in actuation technology by Kyntronics have combined the power of hydraulics with the precision control of servo technology resulting in an actuation system with superior performance. In addition, the electro-hydraulic actuator has a reduced cost compared to EMA actuators while eliminating many of the disadvantages of hydraulic and electro-mechanical actuation technology.
The Kyntronics SMART Hydraulic Actuator (SHA) is a very cost-effective solution for a multitude of situations ranging from simple applications requiring a load to be moved from point A to point B, to higher precision applications with position, force and speed control and multiple actuator synchronization.
To discuss your application and see how the SMART Hydraulic Actuator can maximize cost-efficiencies in your business, contact Kyntronics.