Introduction: What is an electric linear actuator?

2019.07.17

Part 1: What is an electric linear actuator and how to choose it?

News and Articles

What is an Electric Linear Actuator and How does it work?

An electric linear actuator is a device that converts the rotational motion of an electric motor (AC or DC motor) into linear motion. The linear motion is created by rotating the actuator’s screw via the motor. The screw turns either clockwise or counter-clockwise, and this causes the shaft (which is basically a nut on the screw) to move in a line, up and down, creating the push/pull effect for the load.

 

An electric linear actuator can be used anywhere a machine pushes or pulls a load, raises or lowers a load, roughly positions a load, or rotates a load. Additionally, electric linear actuators provide safe and clean movements with accurate motion control that the operator has full control over. They are energy efficient and have a long lifespan that requires little to no maintenance.

 

TiMOTION specializes in electric linear actuators solutions that are best suited for medical, industrial, workplace, and home furniture applications.

 

There are many components and options to an electromechanical linear actuator. TiMOTION is a vertically integrated company. We are able to customize, design, and manufacture all of these components in the house for a customer depending on their application needs. We manufacture motors and components, including the spindle and drive nut, for our electric actuators. Plastic injection molding and PC board manufacturing are done in-house to ensure high product quality and durability. Building our own PC boards allows TiMOTION to optimize the level of software and various movements needed within an application.  A primary example of this is combining multiple linear actuators with position feedback to create synchronized movement. 

 

We will discuss a new subject in each section related to the basics of an electric linear actuator and the factors to consider when purchasing components for a linear motion system. In this section of the white paper, we will discuss the common styles of an electric actuator and how to select the right actuator for your applications. Next, we will review the internal and external components of a linear actuator. Then, we will cover the safety-related options that can be added to an actuator. Following that, we will explain the various actuator load and speed characteristics to consider and how it can be adjusted to meet the applications’ needs. We will follow that with the various levels of IP ratings an actuator can have for liquid and dust protection as well as lubrication that goes into an actuator. Finally, we will discuss different position feedback sensors that are used in electric linear motion systems.


Common Styles of Electric Actuators
TiMOTION designs and manufactures various styles of linear actuators that are all interchangeably customizable to fit a customer's application needs. Some common styles of electric or electromechanical linear actuators include:

 

A.    Parallel Drive Actuator - The motor is directly parallel to the drive spindle.  Typically these types of electric linear actuators are spur gear or belt-driven with more gear ratio options. Parallel drive actuators allow for a wider range of loads and speeds, however, they can operate louder than worm gear driven actuators. Some examples of parallel drive actuators that TiMOTION manufactures can be seen in our TA2, TA2P, MA1, and TA16 models.

 

 

B.    Right-Angle or "L" Drive Actuator - The motor is set perpendicular to the drive spindle. Typically these types of electric linear actuators are worm gear driven. Worm gear-driven motors have fewer gear ratio options, however, because of that they are more efficient than spur gear-driven motors and operate with low noise. In addition, one of the key benefits of a worm gear driven, right angle electric linear actuator is increased self-locking ability.  Some examples of right-angle drive actuators that TiMOTION manufactures can be seen in our TA1, TA4, TA7, TA9, TA10, TA12, and TA23 models.

 

 

C.    Inline Actuators - An electric inline actuator has a longer retracted length, but is designed specifically to fit into smaller or compact spaces. The inline actuator is typically made up of a motor, planetary gear assembly and drive spindle.  These usually operate at a higher noise level. Examples of inline actuators can be seen in our JP3 and JP4 models.

 

 

D.    Gear Motors - Gear motors allow for economical and flexible designs when matching them with various external spindle assemblies. The compact design is typically worm gear driven and an excellent choice for mechanical synchronization. Examples of gear motors can be seen in TiMOTION's TGM1, TGM2, TGM3, TGM4, TGM5, and TGM7 models.

 

 

E.    Dual Motor - A dual motor linear actuator creates movement in two directions either individually or simultaneously. This minimizes the number of linear actuators required in a particular application. They are also typically worm gear-driven motors, which operate at a lower noise level.  While these are typically more expensive per unit, the total system cost will be more economical due to fewer parts. An example of this can be seen in our TT1 model.

 

 

F.    Linear Slide Actuator - This actuator style creates a linear movement without the use of an outer tube. It utilizes a plastic slide mechanism that travels across the actuator, attached to the frame of common household furniture (such as power recliners and couches) seen in our TA5L and TA5P actuators. 

 

 

G.    Electric Lifting Column - TiMOTION manufactures lifting columns catering to the industrial, medical, and ergonomic markets. The primary advantage of an electric column is its ability to vertically lift high loads while retaining a high degree of stability. Our industrial and medical grade columns are designed for applications such as medical and bariatric beds and height-adjustable industrial work stations, where worker and patient safety is essential. Some examples of these columns are the TL3, TL8, TL17, and TL18. Our office ergonomic columns come in various colors, shapes, orientations, as well as 2 or 3 stages for BIFMA compatibility depending on user preference. Some examples of TiMOTION’s office ergonomic columns can be seen on the TL4, TL5, TL7, TL9, TL13, TL14, and TL15.

 

 

How to Choose the Right Electric Linear Actuator for Your Application?

Choosing the right electric actuator is an essential part of any successful automation project. There are many models of actuators – parallel, L-shaped, or in-line motor – which can be used in a wide range of applications.

 

Each project need is unique. To help you select the right actuator, the application and its technical constraints must be taken into account: speed, load, duty cycle, available space, environment, and more.

 

1.       Define the Required Load

The load to be supported is a determining factor in the actuator choice and will define its various components (motor, nut, spindle, gears, ball bearings, etc).

It is important to define which direction the actuator will operate (pull, push, vertical or horizontal movement) and over which length.

It will also depend on the diameter of the actuator’s inner and outer tubes. All these factors influence the actuator's ability to lift loads and have an impact on its strength.

 

2.       Define the Required Speed

The desired speed is a fundamental parameter in the selection of the actuator.

Not all mechanisms or materials are compatible with high speeds. High speed with a high load can cause premature wear of the actuator and affect its lifetime. Therefore, each device has speed and load that must not be exceeded to protect it from material damage. This speed depends, among other things, on the pitch and the motor characteristics.

 

3.       Define the Duty Cycle

The duty cycle defines the ratio between the on-time and off-time of a device and varies considerably from one application to another. The duty cycle is important to determine the actuator, its materials, and its mechanisms. It helps give the equipment an optimal lifetime and to limit the wear of mechanical parts or possible overheating. 

Electric actuators with parallel motors, for example, with their spur gears, will withstand a higher duty cycle and have a higher number of cycles.

 

4.       Define the Available Space

The choice of the actuator is also based on the space available in the system.

In addition to load, stroke, and speed, it is important to consider whether the actuator will have to operate in a restricted space and if there are any space restrictions to allow integration into the application.

For example, in-line electric actuators, due to the alignment of the motor with the spindle, are more compact, making them ideal for tight installation spaces. An actuator's mounting dimensions depend on the mounting configuration (in-line, L-shaped, or parallel motor).

 

5.       Define the Environment

The environment in which the equipment will operate is a crucial parameter to choose the right electric actuator. Does the equipment operate indoors or outdoors? Is it exposed to dust, solid contaminants or moisture? Does it have to withstand intensive cleaning with detergents or high-pressure cleaning? Depending on the environmental requirements, the materials, and the ingress protection rating (IP) used will differ. Does it require a silent operation? L-shaped electric actuators, for example, with their plastic worm gears, provide a quieter movement, ideal for medical or domestic equipment.

 

Everything is variable; everything is adaptable...

The choice of an electric actuator depends on many parameters. It is important to choose a linear actuator that meets the application requirements.

Every application includes a list of requirements that must be met in order to choose the right electric actuator. The budget is also a factor in project planning. Some unavoidable technical constraints will require a larger budget. The important thing is to evaluate all these parameters to create the most suitable device.

 

We hope that this has helped you develop a better understanding and foundation for electric linear actuators and their incorporation into linear motion systems. Next, we will review the important components inside and outside of an electric linear actuator. If you have further questions and/or would like to help with your next application, please contact our global team. TiMOTION would be glad to assist you. We specialize in partnering with our clients while providing quality solutions for their actuation needs.

This mobile site is designed for compatibility with iOS 8.0+ or Android 5.0+ devices.