Electric actuators differ from hydraulic and pneumatic ones primarily in their energy source and the method used to generate motion. An electric actuator employs a motor and a screw mechanism; a hydraulic one uses pressurized fluid; and a pneumatic one uses compressed air. These differences impact force, precision, dynamic performance, control capabilities, and operational requirements.
\nNo single technology is best for every machine. Hydraulics excel in applications requiring very high forces, while pneumatics are ideal for simple, rapid movements; electric drives, meanwhile, offer extensive possibilities for programming position, speed, and motion profiles. Importantly, modern industrial electric actuators can now generate forces that were until recently the exclusive domain of hydraulics.<\/p>\n
Regardless of the technology, an actuator\u2019s function is to convert available energy into controlled mechanical motion. This typically takes the form of linear movement of a piston rod, carriage, or other actuating element.
\nThe primary difference lies in the method of force generation.<\/p>\n
A typical electric actuator may consist of:<\/p>\n
\u25cf an electric motor,
\n\u25cf a drive screw,
\n\u25cf a nut,
\n\u25cf bearings,
\n\u25cf a piston rod or carriage,
\n\u25cf a housing,
\n\u25cf a coupling or gearbox,
\n\u25cf position sensors or an encoder.<\/p>\n
The motor drives the screw in a rotary motion, and the screw-and-nut mechanism converts this into linear motion. This enables the actuating element not only to move between end positions but also to stop at multiple programmed points. In practice, the design and operating principle of electric actuators directly influence the drive’s potential force, speed, accuracy, and duty cycle.<\/p>\n
A hydraulic actuator utilizes a working fluid supplied to the cylinder under pressure. Its basic components include the cylinder, piston, piston rod, seals, and ports.
\nThe complete system also requires, among other things, a pump, a fluid reservoir, lines, and control valves.<\/p>\n
In a pneumatic actuator, compressed air acts upon the piston. While the cylinder design itself may be relatively simple, the entire system requires a compressed air source, air preparation equipment, lines, and valves.
\nFurthermore, the compressibility of air makes achieving high rigidity and precise position control more difficult than with a properly designed electromechanical drive.<\/p>\n
Electric actuators differ primarily in their motion transmission mechanism, guidance design, motor type, maximum force, and permissible duty cycle.<\/p>\n
AMG Automatyka\u2019s product range comprises two main categories.<\/p>\n
Tolomatic industrial electric actuators are designed for demanding applications, including continuous operation and processes requiring high forces. The range includes solutions capable of forces from a few kN up to 445 kN, featuring screw-driven, rod-style, and rodless designs.<\/p>\n
In contrast, Concens linear actuators are compact DC gear-driven units designed primarily for intermittent operation. The typical duty cycle for this group is 10%, making them well-suited for mechanisms that perform a short movement followed by a prolonged period of inactivity.<\/p>\n
Tolomatic\u2019s industrial designs can utilize ball screws, lead screws, or\u2014for very high forces\u2014planetary roller screws. These solutions are compatible with servo motors and stepper motors and can be configured for specific applications.<\/p>\n
A particularly notable example is the RSX electric actuator. This series was designed as an electromechanical alternative to hydraulics and comprises five sizes generating maximum forces ranging from 89 to 445 kN. RSX actuators are capable of 100% duty cycle operation, utilize planetary roller screws, and\u2014depending on the variant\u2014achieve speeds of up to 760 mm\/s and strokes of up to 1500 mm.<\/p>\n
For lower yet still substantial loads, RSA and RSA-HT actuators are suitable choices. The RSA-HT series is specifically designed for harsh environments, offering forces up to 58 kN, strokes up to 1524 mm, and an IP67-rated option. Variants with either ball screws or planetary roller screws are available.<\/p>\n
In many applications, the drive does not operate continuously. Adjusting a throttle, opening a flap, or repositioning a machine component may take only a few seconds, followed by a standstill lasting several minutes.<\/p>\n
Concens actuators perform well in such conditions.<\/p>\n
The CON electric actuator features a compact design and operates with an external controller. Depending on the variant, it offers a force of 120 to 10,000 N, a stroke of 50\u2013750 mm, a speed of 3\u201370 mm\/s, and a 12 or 24 V DC power supply. The standard housing offers IP66 protection, while versions for more demanding conditions are available for selected models.<\/p>\n
If integrating electronics with the drive is important, an interesting alternative is the ICON actuator with an integrated controller. It retains the force range of 120\u201310,000 N and stroke range of 50\u2013750 mm, while offering Modbus RTU communication via RS-485, motion parameter configuration, and the ability to synchronize the operation of up to eight actuators.<\/p>\n
The operating principle of an electric actuator typically involves converting the motor’s rotary motion into linear motion using a screw mechanism.<\/p>\n
A simplified diagram looks like this:
\nController \u2192 electric motor \u2192 coupling or gearbox \u2192 screw \u2192 nut \u2192 piston rod or carriage \u2192 load<\/p>\n
For example, if the screw pitch is 10 mm per revolution, one full rotation results in a theoretical displacement of 10 mm. The position can then be controlled via motor management and feedback systems.<\/p>\n
This allows the electric actuator’s operation to be precisely tailored to the process\u2014enabling the programming of position, speed, acceleration, and the approach profile to the target point.<\/p>\n
The distinction between single-acting and double-acting actuators applies primarily to hydraulics and pneumatics.<\/p>\n
In a single-acting actuator, the medium drives motion in only one direction. The return stroke is achieved via a spring, the weight of the component, or an external force.<\/p>\n
In a double-acting actuator, the medium can be supplied alternately to both sides of the piston. This allows for the active driving of both the extension and the return strokes. With an electric drive, a change in direction results from reversing the motor’s rotation, so such a division is unnecessary.<\/p>\n
A double-acting pneumatic cylinder has two working ports. Air supplied to the first chamber moves the piston in one direction; once the valve switches, air enters the chamber on the opposite side, causing the return stroke.<\/p>\n
A simplified diagram can be represented as follows:<\/p>\n
pressure in chamber A \u2192 extension
\npressure in chamber B \u2192 retraction<\/p>\n
This solution is simple and fast, but precisely stopping the piston at multiple arbitrary points requires a much more complex system than that of an electrically controlled linear actuator.<\/p>\n
<\/p>\n
Criterion<\/strong><\/td>\n| Electric<\/strong><\/td>\n | Hydraulic<\/strong><\/td>\n | Pneumatic<\/strong><\/td>\n<\/tr>\n | Energy source<\/td>\n | \u00a0Electrical energy<\/td>\n | Pressurized fluid<\/td>\n | Compressed air<\/td>\n<\/tr>\n | Position control<\/td>\n | Very good<\/td>\n | Good with advanced control systems<\/td>\n | Limited in simple systems<\/td>\n<\/tr>\n | Multiple programmable positions<\/td>\n | Easy to implement<\/td>\n | Possible<\/td>\n | More difficult<\/td>\n<\/tr>\n | Speed \u200b\u200bcontrol<\/td>\n | Very good<\/td>\n | Good<\/td>\n | Good for simple movements<\/td>\n<\/tr>\n | Very high forces<\/td>\n | Possible with appropriate designs<\/td>\n | Excellent capabilities<\/td>\n | Lower than hydraulic systems<\/td>\n<\/tr>\n | Rigidity<\/td>\n | High<\/td>\n | High<\/td>\n | Lower<\/td>\n<\/tr>\n | Auxiliary equipment<\/td>\n | Power supply and controls<\/td>\n | Pump, reservoir, lines, valves<\/td>\n | Compressor, lines, valves<\/td>\n<\/tr>\n | Risk of medium leakage<\/td>\n | None<\/td>\n | Yes<\/td>\n | No working fluid<\/td>\n<\/tr>\n | Motion programming<\/td>\n | Very extensive<\/td>\n | Requires appropriate controls<\/td>\n | \u00a0Limited in simple systems<\/td>\n<\/tr>\n | Typical profile<\/td>\n | Multi-position, programmable<\/td>\n | Heavy loads<\/td>\n | Rapid point-to-point movement<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n | <\/p>\n It is worth noting that the limit regarding maximum forces has shifted significantly. The industrial RSX model offered by AMG achieves up to 445 kN; therefore, in certain processes, an electromechanical solution can directly replace a hydraulic cylinder.<\/p>\n What are the advantages of an electric actuator?<\/h2>\nThe greatest advantage of an electric drive is the ability to precisely control motion without the need for a separate hydraulic or pneumatic system.<\/p>\n Programmable positioning<\/h3>\nThe controller can determine position, speed, acceleration, and direction of movement. Consequently, a single axis can execute multiple different positions within one cycle.<\/p>\n Easy adjustment of process parameters<\/h3>\nStroke, speed, or stop positions can be changed via software, eliminating the need for mechanical limit switch adjustments.<\/p>\n Control over the entire motion profile<\/h3>\nThe actuator can rapidly advance the tool toward the workpiece, decelerate before contact, perform the actual operation at a controlled speed, and then quickly retract.<\/p>\n Reduced infrastructure requirements<\/h3>\nElectric drives do not require hydraulic pumps, oil reservoirs, or centralized compressed air systems. Programmability and the ability to operate without extensive hydraulic or pneumatic infrastructure are core design principles of Tolomatic industrial actuators.<\/p>\n Integrated control capabilities<\/h3>\nThe ICON model is an example of this, featuring a controller built directly into the unit. Modbus RTU communication via RS-485 and multi-axis synchronization capabilities reduce the number of separate components required to build the system.<\/p>\n What are the limitations of electric actuators?<\/h2>\nAn electric drive is not automatically the best solution for every application.<\/p>\n For simple point-to-point motion\u2014where compressed air infrastructure is already available at the facility\u2014a pneumatic cylinder may be a simpler and more cost-effective solution.<\/p>\n Hydraulics remain an attractive option for applications requiring very high forces within a compact space, especially when a hydraulic system is already in place.<\/p>\n For electric actuators, however, special attention must be paid to:<\/p>\n \u25cf screw selection, It is also important not to treat all electric actuators the same way. The industrial RSX model can operate with a 100% duty cycle, whereas compact Concens designs are typically intended for intermittent operation with a 10% duty cycle.<\/p>\n When should you choose a hydraulic actuator?<\/h2>\nHydraulics remain a good solution where very high force is the priority and precise programming of multiple positions is not a primary requirement.<\/p>\n Typical examples include:<\/p>\n \u25cf heavy-duty presses, However, this does not mean that every high-force application requires hydraulics.<\/p>\n For pressing, bending, clamping, or durability testing, it is also worth considering the RSX electric actuator, which was designed specifically as an alternative to hydraulic systems. Its force range of 89\u2013294 kN allows it to be used in heavy industrial processes as well.<\/p>\n When should you choose a pneumatic actuator?<\/h2>\nPneumatics work well for simple, rapid movements, especially when two end positions are sufficient. It can be a good choice for:<\/p>\n \u25cf product pushing\/ejection, However, if the machine needs to handle multiple positions, change motion profiles based on the recipe, or precisely control speed, electric drives begin to offer the advantage.<\/p>\n When is an electric actuator the better choice?<\/h2>\nAn electric actuator is a good choice when the movement is not merely a simple extend-and-retract action, but a programmable part of the process.<\/p>\n It offers the greatest advantage in cases involving:<\/p>\n \u25cf multiple intermediate positions, However, selecting the right category of device is crucial.<\/p>\n For heavy-duty machines operating with high forces and demanding cycles, Tolomatic industrial electric actuators are the starting point. The product range covers everything from medium-load applications to solutions capable of handling extreme forces.<\/p>\n If a durable actuator is needed for harsh conditions but a force of 445 kN is not required, the RSA\/RSA-HT series offers up to 58 kN and is available with ball or planetary screws, as well as an IP67 rating.<\/p>\n For intermittent motion, Concens linear actuators may be a better solution\u2014especially when compact dimensions, 12\/24 V DC power, or suitability for mobile systems are key factors.<\/p>\n Where are industrial electric actuators used?<\/h2>\n |