What is a Linear Actuator?
A linear actuator is a motion device that creates force and motion in a straight line. A linear actuator consists of a rotary motor (stepper, brush DC or brushless servo) and a threaded lead screw with a precision nut. As the motor’s rotor spins, the linear actuator converts the motor’s rotation into linear motion by moving the nut in a straight line. The push or pull linear motion is achieved directly through the nut and the lead screw.
What Does a Linear Actuator Do?
Linear actuators open automatic doors. They adjust car seats. They’re used to move patients through MRI machines and CT scanners, and linear actuators provide the back-and-forth movement for thousands of items that people use every day, in numerous industries including manufacturing, robotics, healthcare, automotive, aerospace, home automation and many others. straight-line movement provided by linear actuators can be used to lift, drop, slide, adjust, tilt, push or pull objects with the simple push of a button. Today there are hundreds of millions of linear actuators used in the world to perform different tasks. Lin
How Does a Linear Actuator Work?
A linear actuator actuates - or moves - in a straight line. The primary reason for designing a linear actuator into a system is to address the need to accurately move a payload in a linear fashion, rather than a rotary one. The operation of a Linear actuator is simple. A lead screw (or ballscrew) acts to translate the clockwise and counterclockwise rotary force (torque) of the motor into back-and-forth linear motion for a nut traveling along the length of screw.
What are the most Common Industries & Applications for Linear Actuators?
Linear Actuators are used in various applications that require a load to either be lifted, lowered, pushed, pulled, rotated or positioned. The most popular industrial applications for Linear Actuators include:
- Packaging
- Lab diagnostic devices
- Medical equipment
- Food & Beverage processing
- X-Ray imaging equipment
- Robotics
- Pharmaceutical
- Semiconductor
- Factory automation
- HVAC
- Material handling
- Clean energy
- 2D and 3D Printing
- Automotive & industrial vehicles
- Machine tools
- Marine
- Aerospace
What Are the Different Types of Linear Actuators?
Linear actuators come in several configurations to fit different applications. Linear actuators are categorized by their mechanical drive mechanism, guide and housing. The most common types of linear actuators include:
- Hybrid Stepper Motor Linear Actuators – are preferred by equipment designers who require high performance and endurance in a very small package.
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Dual-Motion - provide independent linear and rotary motion from a single compact actuator package. This type of actuator is an ideal replacement for bulky and complex mechanisms.
- Can-Stack Stepper Motor Linear Actuators - provide a broader range of thrust and speed to address a wider range of applications.
- External Linear Actuators – affix the lead screw onto the shaft of the motor.This type is commonly chosen to power linear slide systems in the 60-500mm stroke range.
- Non-Captive Linear Actuators – locate the nut inside the motor and allow the screw to move linearly through the actuator.This type is common for stroke lengths of 30-200mm.
- Captive Linear Actuators - locates the nut inside the actuator body (like non-captive actuators) but the front side features a linear spline attached to the screw, which prevents the rotation of the screw and provides linear output.
- Electro-Mechanical Actuators - combine a motor with an external linear drive element, which could be a ballscrew, lead screw, rack and pinion, or belt.Gearboxes and linear guide elements might also be included.
- Hydraulic Actuators - are hydraulic cylinders with a piston that uses an incompressible liquid to produce unbalanced pressure on the piston to create linear displacement.
- Pneumatic Actuators - use compressed air to convert energy into mechanical motion. They consist of a piston, cylinder and a valve or port, which can produce linear or rotary mechanical motion.
- Voice Coil Actuators - have magnets that generate a magnetic field which produces current that moves a coil to create motion in a shaft. The force of the motion is proportional to the turns of the coil.
The performance, capacity, speed, force and precision of linear actuators is dependent upon a wide range of configuration aspects - including the size of the motor, the diameter of the lead or pitch of the drive screw, the gearbox ratio (if there is one), and any other accessories, such as limit switches and position sensing encoders.
How To Choose the Right Linear Actuator:
In order to correctly size a linear actuator, the following variables must be considered:
- How much linear force is needed to move the load?
- What is the linear distance that the load must travel?
- How much time is required to execute the movement?
What Criteria Should Designers Consider for Evaluating Linear Actuators?
The following capabilities should be analyzed when selecting a linear actuator:
- High repeatability
- Positioning accuracy
- Smooth operation
- Long life
- Easy (to no) maintenance
- Ruggedness and reliability for harsh environments
- Compact design
- Safe operation
- Versatility.
What is the Load Capacity of a Linear Actuator?
The load capacity of a linear actuator is determined by its ability to move and hold a load. Loading refers to the forces that push towards or compress the linear actuator as well as the forces that pull away from it. The International Organization of Standards (ISO) standard 14728-1:2017 describes the load fatigue for linear actuators.
The two measurements for a linear actuator’s load capacity are dynamic and static. When a linear actuator is in the dynamic position, it is moving. When a linear actuator is in the static position, it is holding a load in a set position. Static load capacity is determined by how much an actuator can safely hold without back-driving or being damaged.
How Long do Linear Actuators Last?
With proper application consideration, Haydon Kerk linear actuators deliver up to 20 million cycles. Motor fatigue will be determined by each customer’s unique application.
The first step in maximizing life is choosing a motor which has a safety factor of 2 or more. The second step is to ensure that the system is mechanically sound. This is accomplished by minimizing side loading, unbalanced loads and impact loads. Each system should be designed to allow for effective heat dissipation. If these simple, yet effective guidelines are followed, the linear actuators will provide reliable operation over millions of cycles.
Conclusion:
- Linear actuators convert rotational motion into push or pull linear motion, which can be used for lifting, dropping, sliding, or tilting machines or materials.
- Although the function of all linear actuators is the same, there are several different ways the motion is achieved.
- Linear actuators come in several configurations to fit any possible application, environment, setting or industry.
Haydon Kerk Motion Solutions has the exact size and type of linear actuator to solve your motion application.
FAQs
1. What is a linear actuator?
A linear actuator is a motion device that creates force and movement in a straight line. It typically consists of a rotary motor and a threaded lead screw with a precision nut that converts rotary motion into linear push or pull motion.
2. How does a linear actuator work?
A linear actuator works by converting the rotary motion of a motor into linear motion using a lead screw or ball screw. As the motor turns clockwise or counterclockwise, the nut travels along the screw, producing straight‑line movement.
3. What does a linear actuator do?
A linear actuator provides controlled straight‑line motion that can be used to lift, lower, push, pull, slide, tilt, or position objects in mechanical and automated systems.
4. What components make up a linear actuator?
A linear actuator consists of a rotary motor (stepper, brushed DC, or brushless servo), a threaded lead screw, and a precision nut that translates the motor’s rotation into linear motion.
5. What industries commonly use linear actuators?
Linear actuators are commonly used in industries such as packaging, medical equipment, laboratory diagnostics, robotics, pharmaceutical manufacturing, semiconductor equipment, factory automation, HVAC, material handling, clean energy, automotive, marine, and aerospace applications.
6. Why are linear actuators used instead of rotary motion?
Linear actuators are used when a system requires precise movement of a load in a straight line, rather than rotational motion, which simplifies payload positioning and control.
7. What are the main types of linear actuators?
Linear actuators are categorized by their drive mechanism, guide, and housing. Common types include hybrid stepper motor linear actuators and dual‑motion linear actuators that provide both linear and rotary motion.
8. What is the difference between a linear actuator and a rotary motor?
A rotary motor produces rotational motion, while a linear actuator converts rotational motion into controlled straight-line movement. Linear actuators are used when precise pushing, pulling, lifting, or positioning is required.
9. What are the advantages of stepper motor linear actuators?
Stepper motor linear actuators provide precise positioning, repeatable motion, open-loop control capability, compact design, and excellent reliability for automation and motion control applications.
10. What is the difference between captive and non-captive linear actuators?
Captive linear actuators use a built-in mechanism that prevents lead screw rotation and provides direct linear output. Non-captive linear actuators allow the lead screw to move through the motor body and are often selected for applications requiring longer travel lengths.
11. What factors should be considered when selecting a linear actuator?
Important selection criteria include required force, stroke length, speed, duty cycle, positioning accuracy, available installation space, environmental conditions, and expected operating life.
12. What applications use linear actuators?
Linear actuators are commonly used in robotics, medical equipment, laboratory automation, packaging machinery, semiconductor tools, material handling systems, factory automation equipment, and automotive applications.
13. What determines the load capacity of a linear actuator?
Load capacity is influenced by motor size, lead screw design, actuator configuration, operating speed, mounting orientation, and application requirements. Both dynamic and static load conditions should be evaluated during actuator selection.
14. How accurate are linear actuators?
Linear actuator accuracy depends on factors such as motor technology, lead screw pitch, system design, and control method. Stepper motor linear actuators are commonly selected for applications requiring repeatable and precise positioning.
15. How long do linear actuators last?
Service life depends on operating conditions, side loading, duty cycle, heat management, maintenance practices, and application design. Properly integrated actuators can provide millions of reliable motion cycles.
16. Can linear actuators be customized?
Yes. Linear actuators can be customized with different motor sizes, stroke lengths, precision modified ACME lead screws, mounting configurations, feedback devices, wiring options, and performance characteristics to meet specific application requirements.
17. What is the difference between a lead screw and a ball screw actuator?
Lead screw actuators typically offer simpler designs, cost-effectiveness, and self-locking characteristics, while ball screw actuators generally provide higher efficiency, greater speeds, and lower friction for demanding motion applications.
18. Are linear actuators suitable for medical devices?
Yes. Linear actuators are widely used in medical and laboratory equipment because they deliver precise, repeatable, compact, and controlled motion for imaging systems, diagnostic devices, dispensing equipment, and patient handling systems.
19. What is a dual-motion linear actuator?
A dual-motion linear actuator provides independent linear and rotary motion from a single compact device, helping simplify machine design and reduce system complexity.
20. What are the benefits of electromechanical linear actuators?
Electromechanical linear actuators offer precise control, high efficiency, clean operation, low maintenance requirements, and easy integration into automated equipment compared to many fluid-powered alternatives.