5 Frequently Asked Questions About Electric Actuators
Electric actuators are an excellent replacement for hydraulic cylinders in many situations. Despite the growing number of linear electric actuators, we do often receive certain questions from customers considering electric actuators. In this blog, we will elaborate on 5 of the most common problems.
1. What Might Be the Reasons for Choosing Electric Actuators Instead of Hydraulic Actuators?
Hydraulic actuators have some advantages in certain situations. They have high power density, low component acquisition cost, medium to high stiffness, and high speed, and are a common technology with multiple commercial outlets. However, in some cases, hydraulic actuators may be less beneficial to the system. They are moderately accurate and repeatable without the additional assistance of additional tuning equipment.
They also have intricate installation and maintenance due to hydraulic pumps and oil lines. Additionally, they have high installation costs, low energy efficiency, high environmental impact, and limited scalability and modularity. In these cases, electric actuators offer a better solution.
2. What Are the Main Benefits of Using an Electric Actuator System Compared to a Hydraulic System?
Electric actuators provide high speed and force, are flexible and easy to program for a variety of load conditions, are highly accurate and repeatable, are efficient, simple to install, require little maintenance, and are environmentally friendly.
By eliminating the use of hydraulics, users can eliminate oil spills, reduce contamination and improve worker safety.
Other environmental benefits of electric driving include:
- Higher energy efficiency/lower energy consumption
- Quieter operation/lower noise level.
- Virtually zero power consumption when not running (hydraulic system pumps that run during idle periods use a lot of energy)
- Also, there is no hydraulic fluid disposal (during normal maintenance or repairs, hydraulic fluid needs to be properly disposed of).
- Electric actuators are also a non-toxic solution, especially in the food industry.
3. What Challenges Will You Encounter when Replacing the Hydraulic System?
Certain transition challenges arise when converting from hydraulic to electric actuator systems. If the system has multiple hydraulic actuators, the step-by-step approach to conversion can be a more difficult process than converting all machine axes simultaneously.
If your load conditions are severe, you should consider using bumpers or adjusting the motion curve to mitigate shock loads and high vibration.
Properly converting from one actuation method to another requires an understanding of how to properly size the new actuator. The actual stroke length should be measured and taken into account for installation. For a simple estimate of the required force, the piston diameter times the pump pressure should guide your electric actuator selection process, choosing the ideal measured force and acceptable calculated force.
Engineers should know the speed of the actuator (measured time required to extend over retract), the number of cycles per minute, hour, and day, the number of shifts or days per week the actuator will be used, and the operating environment. The operating environment will include temperature, dust, liquids, and hazardous conditions.
4. What Advances in Electric Drives Have Improved Current Processes?
Advances in electromechanical drives include combining rotary servo motors with rotary-to-linear mechanical transmissions such as roller screws. Roller screws have nuts that run along threaded rods that mesh with each other in a nut housing much like a planetary gearbox.
This leads to some significant advantages of electric roller screw actuators:
- They provide more points of contact than ball screws, which means that applied forces can be distributed over a larger surface area, reducing stress levels and increasing service life.
- The rollers connect the nut to the screw for synchronous motion without recirculation, allowing for higher rotational and linear speeds in applications requiring large amounts of force. There is also less vibration and noise at higher speeds due to the absence of recirculating balls.
- The high load capacity of roller screws allows for smaller and lighter packaging than ball screws.
- To further optimize weight and package size, the new electric actuator combines a roller screw and a servo motor into one. The integration of the motor creates a smaller package size and reduces component count.
- The direct drive of the roller screw mechanism eliminates backlash caused by couplings and drive trains, resulting in higher dynamic response and better performance.
Advances in brushless motors with feedback devices have provided greater precision and repeatability along with the pairing of servo motors and roller screws.
Traditional electric actuators usually use single-phase or three-phase induction motors as the driving force. The problem with this design is that when the actuator needs to change direction or start and stop, the operation is limited by the temperature rise of the motor and therefore the limited duty cycle. The use of continuous-duty cycle brushless DC motors along with roller screws helps to address this limitation. Feedback devices allow very precise control of the position and velocity of the actuator output stem.
5. Which Industries Are Currently Using Electric Actuators to Seek Benefits
Many industries are using electric linear pneumatic actuators to benefit their systems. For example, they are used in the automotive, graphics, food, and process industries such as welding equipment, metering and filling applications, pressure applications, etc.
Machines in the food processing industry use electric actuators in filling machines, production blocks, transport, and product indexing.
The oil and gas industry uses electric actuators instead of hydraulic and pneumatic actuators due to their environmental benefits as well as flexible and accurate control. Both hydraulic and pneumatic systems are at risk of leaks, resulting in hazardous situations (e.g. methane is commonly used in oil fields as a polluting or flammable gas for pneumatic fluids). Electric actuators are increasingly being used to address all of these issues.
The above briefly introduces some common problems of electric actuators. If you want to buy electric actuators, please contact us.
UG Controls is a professional custom valve actuator manufacturer. We use our engineering expertise and industry experience to continuously improve our products, striving to provide efficient solutions and competitive prices. UG is also a global supplier of highly engineered actuators and accessories to the Oil & Gas, Mining, Chemical, Pharmaceutical, Water & Power, Food & Beverage, and general industrial markets.