What Are Micro Linear Actuators?

What Are Micro Linear Actuators?

In Simple terms a Micro Linear Actuator is basically a Small Actuator with a small body size and therefore a small stroke range. A typical Micro Actuator will have stroke's ranging from just a few millimeters to around 50mm. As a result of their small package size and small strokes they also pack less force than a traditional Linear Actuator because their power source (usually a Motor) would need to be smaller and thus offer less force to the Micro Actuator. 

Where are Micro Linear Actuators used?

Most people don't realize that technology is anything that makes our lives easier. A pencil, a chair, and a supercomputer are all examples of technology. We live in an age where technology is advancing so fast that it is impossible to keep up with the breakthroughs happening in every branch of science and engineering. It's an exciting time to be alive.

Are you aware that 45% of work people are paid to do can be automated with current technology? That represents around $2 trillion in annual wages. One of the important components advancing automation technology is recent developments in micro linear actuators.

Linear actuators are a simple but vital component in any device or machine to enable movement in a linear direction. The same principle applies with a micro linear actuator, only on a smaller scale.

Are you curious and want to learn more about actuators? Want to know exactly how to include actuators in your next project? Well, get comfortable and keep reading as we are about to cover everything you need to know for putting your projects to motion with linear actuators.

Micro Actuator Types

An actuator is a mechanical device used to move or control parts of a machine or otherwise stationary object. Without actuators, nothing can be designed to move on its own. The most basic requirements of an actuator, enabling controlled movement, are a control signal and energy source.

The control signal could be nothing more than pushing a button or an automatic switch triggered by outside conditions. The energy source is what powers the movement to do work. Actuators are categorized by their energy source, the direction of movement they enable, and the size/power of the actuator. Some common types of Micro actuators include:

  • Pneumatic
  • Electromechanical
  • Linear motor
  • Thermal
  • Magnetic
  • Mechanical
  • Human-powered

Defined by conversion:

  • Circular (rotary movement)
  • Linear (straight pull and push movement)

Defined by size/power

  • Industrial strength actuators
  • Soft actuators
  • Micro actuators

The different types of actuators are used according to the function and role they play in a controlled system. For example, industrial-strength hydraulic cylinder linear actuators tilt and move the bucket of excavators and lift the bed of dump trucks for quick unloading.

For more on the different types of actuators and their common uses read this article entitled Examples of Actuators and How They Work. For the purposes of this article, we will concentrate on linear actuators and specifically micro linear actuators, also known as mini linear actuators.

How do Linear Actuators Work?

The invention of linear actuators was as important to our modern-day society as the wheel was to ancient society. Although innovation has improved on the original design, the principles of how linear actuators work remain the same.

The most commonly used linear actuators used in automation are electric. Powered by AC/DC electric motors of different stroke options, they convert the rotary motion of an electric motor to the linear motion of a straight line. They are able to do push or pull work.

The high speed of the motor's rotation is slowed down with a multiple state helical gearbox. The lower the speed the higher the torque. The torque produced turns a lead screw creating the linear motion of a drive screw/nut. Reversing the polarity of the motor reverses the direction of motion from push to pull and vice-versa.

Performance Metrics

Choosing the right linear actuator for the job is essential to the success of your design, project, and desired outcome.  Performance metrics are the rated outputs produced and other factors that affect the performance of the actuator. 

Force or Torque

Arguably the most important performance metric to consider is torque. Choosing an actuator with too much torque is inefficient and even dangerous. For example, a gate closed with an actuator with 800lbs of force, without a safety kill switch, could easily crush a hand or worse.

On the other hand, not enough torque and the actuator will not be capable of performing the push and pull work needed. Selecting the right actuator begins with calculating the torque needed for the specific job to ensure efficient, smooth, and safe operation.

Torque Ratings

There are several different torque ratings for actuators that are important to know. These torque ratings will determine what type of application and to what degree the actuator can be used. Different torque ratings include:

  • Breaking torque, the torque needed to initiate movement
  • Running torque, the torque needed to overcome gravitational and friction forces of a load
  • Static load torque
  • Dynamic load torque

Take the common example of opening and closing a valve. If the actuator used has a torque rating insufficient to initiate the opening/closing of the valve and open/close the valve won't function or get stuck mid-struck. Too much torque could damage or break the valve. Torque ratings are measured directly in pounds of force (lbs).

A margin of error of 25% more than the required torque rating needed is suggested in order to avoid malfunctions and safety concerns. Actuator torque ratings should match the values of the controlled loop system in which they operate.

Torque Value Considerations

As mentioned above, the amount of torque of the linear actuator is determined by the gearbox. Use a step-up gearbox actuator to enable the actuator to operate at different torques. Note: this will affect the speed at which the actuator pushes and pulls.

A low torque rating means the actuator can only function for a small range of applications and loads. A higher torque rating means the actuator will be sufficient over a wide range of loads and applications.

What Is the Difference Between Static Load and Dynamic Load?

In general, the term "static" means stationary or fixed, and dynamic means action or change. Therefore a static load is the amount of force pull or push applied to the actuator while it is at rest (not moving). The dynamic load is the amount of force applied while the actuator is moving.

These values determine the maximum or recommended trust loads that can be applied to the actuator safely. Applying more force to then the rated static or dynamic load may result in malfunction or damage to the actuator and or other components of the system it is used in.

Speed

The speed at which the actuator pushes and pulls is a metric to consider based on the load it needs to move. Generally speaking, the heavier the load the slower the speed. The speed of the linear actuator is measured in inches per second ("/s).

Different speeds are achieved by using different gear ratios. Keep in mind that changing the gear ratio also changes the torque or force. The trade-off – higher force means lower speed and higher speed means lower force.

Operating Conditions

There are actuators designed to operate in every imaginable environment. Make sure the actuator you used is designed for inside or outside use, extreme temperatures, or in dusty/dirty conditions. Check the temperature range ratings and compare them to your operating conditions.

Durability

The durability of an actuator is largely determined by the materials used in its construction. Premium linear actuators are built with high-grade materials and manufactured with corrosion resistance for maximum lifespan. Our actuators are trusted by industry partners that require the highest quality and durable components such as NASA, SpaceX, Tesla Motors, General Motors, General Atomics, and many more.

Noise level

This performance metric is a concern for indoor use in buildings and homes. The volume of sound created by the actuator is measured in decibels (dB). DeciBels measure the intensity or loudness of a sound. For example, a jet engine at take-off is 140 dB while a soft whisper is only 30 dB.

Nearly silent actuators can be manufactured using sound-absorbing housing, but there will always be some sound escaping through vents. This metric is often recorded as "No Load" noise level, in other words, before it is made to do any push/pull work.

Energy Efficiency

Concern for the environment is a pressing issue these days. According to an analysis of utility costs performed by the University of Michigan, the average American household could save $1,560 a year by making the home more energy-efficient. When you consider living in the home for fifty years the overall savings is over $75,000. However when it comes to Micro Linear Actuators there really are no power saving options available, they all require electricity to perform their function by creating linear motion, the only way to create energy efficient actuators is through design by using more complicated and expensive design features such as reciprocating ball leadscrews. 

Using energy-efficient devices and appliances saves money and the environment. The government requires that manufacturers test and rate the energy efficiency of the devices they produce. Some linear actuators are far energy-efficient than others, so it pays to pay attention to this performance metric if its important to you. 

Specifications of Note

Linear actuators come in all sorts of shapes, sizes, weights, and other specifications to fit various applications. When shopping for linear actuators it helps to understand the following terms and how they fit into your project.

Stroke Length

The stroke length determines the range of movement from retracted to extended. Other specifications of note are the retracted length and extended length.

You will need to make sure the length of the actuator allows for it to be installed where you plan to mount it. Measuring how far the actuator needs to push and pull to perform its function gives you the stroke length required. Stroke lengths are measured in inches (").

If you require the stroke length to be greater than the actuator's retracted length, a telescoping type actuator is needed. Like in the case of artificial muscles in robots.

Weight

Depending on the application, the weight of the actuator may become important. In some cases, the actuator must be as light as possible as in the case of actuators in motor vehicles.

Gear Ratio

The load-to-motor inertia, or gear ratio, gives you the speed and torque of the push/pull motion it creates. If the motor inertia is too low compared to the load inertia, the load will cause resonance and overshoot. This decreases efficiency which in turn increases the operating cost of the actuator.

At the same time, if the motor inertia is too high relative to the load inertia, you are using an oversized motor which, of course, costs more to run than necessary. The right gear ratio corresponds with the correct load capacity you will need.

Self Locking Force

Self-locking is a safety feature built into many linear actuators. If sufficient force is applied against the actuator as it moves a kill switch turns off the device to prevent injury or damage to the device and/or load. The self locking force metric measures the amount of force needed to stop or reverse the linear motion of the actuator.

Also, take note of safety certifications like CE and ROHS certifications. For more detailed information on linear actuators,

Selecting the Right Actuator for the Job

At this point, you should have a good idea of how various factors of actuators change according to their function. Time to put shopping for your actuator into motion. Follow this step-by-step process and you will find exactly what you need, no matter the application.

Step One: Type of Movement

Do you require rotary or linear motion? Again, linear actuators push and pull in a straight line while rotary actuators (like motors) create circular motion.

Step two: Energy Source

Electrical actuators are best suited for most applications but that doesn't mean other types of actuators aren't better suited for the job. For example, if you need to operate far from power sources you need an actuator that doesn't require voltage to operate.

Step three: Level of Precision

Actuators that perform heavy-duty work in construction may require less precision than other applications. For example, manufacturing applications may require high levels of precision to perform tasks such as assembly work. In addition, they may need to perform the same operation over and over with very little margin of error.

Step Four: Amount of Force

As the purpose of linear actuators is to push, pull, lift, or otherwise move an object (load), determining how much force is needed is essential to choosing the right actuator for the job. The load capacity tells you how heavy a load you can lift with the actuator.

This is a good indication of the force required to push or pull the load as well, with a little tacked on for drag resistance you should overestimate the force needed to be sure the actuator always has enough power to perform the task without straining its limits.

Step Five: Length of Movement

Measure the exact length you need to move the load for the full range of motion required. The distance the linear actuator covers when fully open is called the stroke length.

In some projects, you may have some breathing room when it comes to stroke length while other projects may require a more precise and even custom-made stroke length.

Step Six: Speed of Movement

How quickly do you need or want the actuator to open and close? Think carefully about the time it will take to perform the full range of motion of the linear actuator. In some cases, a slow speed is necessary to get the amount of torque or force you need.

In some projects, you may want a faster speed, such as opening a gate or door without having to wait a long time. A good example of this is a dog door. You may be more patient than a dog and the dog might try forcing itself in before the opening is large enough, potentially injuring the dog or damaging the door.

Step Seven: Operating Environment

Make sure the actuator you buy for your project will stand up against the environment it will be operating in. If the actuator will be used outdoors, can it operate in the colds of the winter and the heat of the summer? Will the actuator need to stand up against dusty or dirty environments?

Step Eight: Mounting

The last consideration is how the linear actuator will be mounted. Check to see if there is ample space for the actuator to be mounted. If not a smaller-sized actuator may be needed. If using the actuator with prefab conversion brackets, make sure they are compatible or you may end up having to make modifications to the brackets, buy a different actuator, or buy different brackets.

Other Components Used With Actuators

Once you have found the right linear actuator, it is time to pick up the other components you will need to complete the project. It is important to wait until you know which actuator you will use to pick up other components as the compatibility of these components could change according to the type and size of the linear actuator(s) you use.

Power Source

There are linear actuators designed to run off both AC and DC in a range of voltages. The most common are 12 volt DC linear actuators. These actuators are powered by a rechargeable 12-volt battery.

You can set up the actuator to automatically charge by plugging the battery charger into a nearby AC outlet. In which case, you will need to be sure the battery has more than one input socket. Perhaps a better way is to connect the DC actuator through an AC to DC power supply.

Switches

You will need a way to turn the actuator on, off, and reverse direction. In other words, you need to decide on the switching mechanism you will use in your project. This is most simply done with a rocker switch.

Consider how you want the switch to work. Do you want to switch it once and have the actuator completely extract or do you want to hold the switch until it reaches the desired distance? You may want to use switches with LED lights or external limit switches. For more information on how to wire actuators to external limit switches, read this article.

Remote Controls

Actuators can easily be controlled from a distance by using remotes and receivers. Incorporating wireless control into your project gives you the ability to control the actuator from anywhere within the range of the remote. A remote-controlled hidden room or stash spot is a great option as keeping the remote on your keychain would limit access and keep the controls hidden.

We manufacture a universal remote control that can be programmed to control your TV, DVD player, Cable, etc. The remote has three buttons for controlling your Firgelli Automations TV lift as well. Everything you need for controlling your entertainment center in one remote.

Control Boxes

Depending on the complexity of your project, you may want to adjust currents or speeds. This is accomplished by integrating control boxes.

Want to be able to control the linear actuator and/or DC motor in a specific way such as sensor-activated or time activated? Check out our Arduino kit that comes complete with USB cable, LEDs, Sensors, and Arduino.

Other Components You Might Need

Firgelli Automations™ strives to be a one-stop online shop for all your linear actuator project needs. We carry other products that might come in handy such as relays, cable management drag chains, and mounting hardware. If your project requires something you don't see on our site feel free to contact us for advice on sources or alternatives.

Need help with your design concept or how to implement components to customize your projects? Check out our ever-growing tutorials section here.

Mini Linear Actuators: When Smaller Is Needed

There are applications and projects where full-sized linear actuators won't fit or are otherwise impractical. As linear actuators are increasingly used in a wide variety of DIY projects, we were one of the first linear actuator manufacturers to offer push and pull power in a compact size.

These mini linear actuators are ideal for projects that require high precision, ultra-quiet operation, yet in a smaller compact size. We manufacture some of the most innovated mini actuators on the market with stroke lengths from 1 - 25 inches.

Micro Linear Actuators: When Even Smaller Is Needed

The terms mini linear actuators and micro linear actuators are somewhat interchangeable. There is no set rule for what size qualifies an actuator as a "micro" linear actuator but generally speaking, micro linear actuators have strokes less than 300mm and capable of no more than 100lbs of force.

Some linear actuators are so small that "micro" linear actuator is the only term that really fits.

Of course, the smaller the size of the motor the less power you are able to drive the desired push/pull movement. However, there are many applications for micro linear actuators that don't require a large force associated with heavy industry.

Common Applications of Micro Linear Actuators

Micro linear actuators are at the front lines of the most cutting-edge branches of engineering. Used in thousands of applications across many industries, micro linear actuators are used in some of the most advanced devices on the planet.

Robotics

The global manufacturing industry has entered its fourth revolution (Industry 4.0) thanks to innovations in robotics, automation, the internet of things (IoT), and artificial intelligence (AI). The number of industrial robots worldwide is increasing 14% year after year and these labor-saving machines are capable of ever more complicated tasks.

Futurists have popularized the concept of an "age of abundance." The age of abundance is when humanity has the capability to provide products so cheaply and abundantly that they cost next to nothing or are free. AI-driven robotics in manufacturing is the first of many industries to see us closer to such a future.

It seems the days of carved wooden toys supplying entertainment for the young are long gone. As much of the older generation tries to keep up with how to transverse computers and their many applications, kids these days build robots and control them with their smartphones.

The sales of micro linear actuators along with other robotic components are exploding largely due to industrial productivity needs and interest in hobby scale robotics.

Aerospace

Space, the final frontier, is a particularly good "space" for micro linear actuators. The Earth's gravity is the most significant obstacle to man's ambitions to explore and colonize the solar system and beyond. Although costs are being cut by private space companies like SpaceX and Blue Origin, sending anything into space is still extremely expensive.

Miniaturization makes it possible to make devices that perform work in space at a much cheaper cost. Micro linear actuators are small, lightweight, and draw little power – all-important in aerospace applications. Applications of micro linear actuators in Aerospace include:

  • Opening and closing valves
  • Direction control
  • Tracking of solar panels
  • Opening and closing compartments
  • Locking and securing compartments
  • Adjustments of seats and beds
  • Robotic arms
  • Extending and retracting landing gear
  • Extending and retracting sensors for data collection
  • Space-saving solutions such as retracting consoles and tables

Micro linear actuators also have their place on the ground. They are used in prototyping and even training astronauts in flight simulators.

Medical Devices

Micro linear actuators are everywhere in healthcare as well. As medical science converges with engineering, the resulting devices are indeed awe-inspiring.

On the more practical side of things, micro linear actuators are decreasing cost while increasing the reliability and overall functionality of medical devices. You can find micro linear actuators enabling advances in medicare with such applications as:

  • Custom devices for rehabilitation therapy
  • Simulators for educating surgeons
  • Robotic arms for precision surgery
  • Artificial limbs (prosthetics)
  • Medical testing devices
  • Implants and artificial organs
  • Locking mechanisms for wheelchair lifts
  • Microfluidic valves
  • Positioning devices for Esthetic Dentistry

From simple automated adjustments of operating tables to the ultra-precision needs of prosthetic limbs, micro linear actuators are pushing the limits of modern healthcare.

RC Hobbyist

As of 2019, there were 1.1 million hobbyist drones and nearly 500,000 registered commercial drones in the US alone. Remote control cars, boats, drones, and planes are a kind of fun that never goes out of style.

Micro linear actuators are used to extend and retract cameras, landing gear, and other equipment. They can be added to models to give them adjustable heights much like the hydraulic lifts of some cars and trucks. You could even build an RC model of an excavator complete with fully operational bucket movements.

Arduino Magic

Arduino is an open-sourced electronics platform that combines easy-to-use hardware and software to build endless automation projects limited only by your imagination. Arduino boards are able to read inputs from sensors such as:

  • Temperature
  • Humidity
  • Ultrasonic distance
  • Infrared emission
  • Sound
  • Optical (light intensity)
  • Gas
  • Water
  • Motion
  • Color

You can use any one or combination of these sensors to trigger and control micro linear actuators in your projects. Program the Arduino board to give you the desired output (movement) based on the sensor(s) readings output. In this way, you can create as complex a project as you dare to take on.

Let's imagine something up shall we? What if we wanted to create a visual representation of the light levels outside?

We could connect an optical sensor to our Arduino board and place it against a window. Connect a micro linear actuator that adjusts according to the amount of light outside. As the actuator extends and retracts it moves an indicator, say the pointing finger of a little person, giving you a visual representation of how much light is outside along the scale.

Check out this video to get a better idea of just what is possible with micro linear actuators and Arduino with a little ingenuity. Unlock your creative genius and use micro linear actuators and Arduino to put your vision in motion.

Buy From Industry Leaders

When you want high precision, low noise level, in a compact design, mini or micro linear actuators are what you need. No matter your DIY project, or engineering ambitions, we are a partner you can trust to deliver the highest quality components in the industry.

For nearly two decades, FRIGELLI Automations has endeavored to push the standards of quality, affordability, and accessibility of the automation industry. We supply actuators to fit every purpose and continuously develop and tweak our designs. Please feel free to contact us with any inquires or if you already know exactly what you want, shop mini linear actuators and put your dreams in motion.

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