Electric Linear Actuators
Are you new to actuators? Have you just learned what an actuator is? You're not alone, and we're happy to help! This page is for you, and we will try to include all the information we can that you need to make an educated decision when selecting what actuator is right for you.
Many people, rather, most people have never needed to use an actuator before, and typically refer to them as 'rams', 'activators', 'electric pistons', or other wild variations. All in all, they all mean the same thing, and we don't mind if you don't like using the technical terms. First thing to know, is that a linear actuator does exactly what its name implies: it actuates (or 'moves') in a linear (or 'straight') fashion
There are many different ways that a motor can do this, and their motion is commonly achieved with a rod extending and retracting, or a slider which moves on a track. Uses for these linear motors vary widely, and they can be used on everything from TV lifts (including drop down lifts), wheelchair ramps, industrial machinery, toys, office and home automation, and even aerospace technology.
So how does a Linear Actuator work?
The Linear motion is created by using a screw or Lead-scew as they are more correctly called. The screw turns either clockwise or counter-clock-wise and this causes the shaft, which is basically a nut on the screw to move up and down the screw as the screw turns. This is what convert rotary motion from the electric motor to linear motion.
The motors used are either AC or DC motors, most however run on 12v dc, but other voltages are also optional. To make the Actuator go the other way you simple reverse the wires from the Actuator (reverse polarity) from the battery or power supply. This is typically done through a switch that automatically reverses the polarity to the motor for you.
Different speeds and forces are achieved by using different gear ratio's inside the linear actuator gearbox system. Please remember in a Linear Actuator, force and speed trade-off against each other. That means if you want high force you have to settle for a lower speed than if you require lower force. This is because the only constant in a Linear Actuator is the Motor speed and force for a given input voltage. Everything after the motor is what is available to be used to create speed and force.
Actuators are available in different strokes, all this means is the screw and shafts are longer or shorter to get the stroke you want. They are also available in different speeds and forces. This is achieved by simple changing the gears that go between the DC motor and the screw. Typically the faster the screw turns the lower the force, because speed and force trade-off against each other.
To make the shaft stop when it gets to the end of the stroke the Actuators have built in limit switches or micro switches as they are sometime known. These limit switches are inside the main actuator shaft and are nothing more than a small switch that are triggered by the nut inside that slides up and down the screw. There is one for the top extended position and one for the lower retracted position. Once the limit is reached the switch is triggered and cuts power to the DC motor. Only if the polarity is reversed can the actuator move which would be in the opposite direction. Without any power the actuator cannot more at all.
Firgelli Automations is a proud supplier for thousands of companies in the above sectors, and more for over fifteen years. In these years, we've learned a thing or two about what first-timers want to know. This will be a regularly updated article with all the links and videos you could possibly need to start your own project with actuators.
What Actuator should I use?
With such a selection of Actuators we manufacture, it can be very easy to get confused and frustrated if you don't know anything about electric motors or actuators in particular. Typically when helping a new client choose the right unit for his or her application, we will ask the following:
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What are you using it for?
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How much force do you need?
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How much stroke ('travel') do you need?
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How fast do you need it to move?
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And finally, how often do you need it to do this?
The significance of these questions is to determine what sort of load will be placed on your future actuator, and what requirements you have. Most people start off with needing a product with X amount of force, which is a fantastic place to begin your search. The Actuator finder page will help you pick the right unit based on force, and narrow your search down, or use our Linear Actuator Force Calculator to determine what force of Actuator you really need. Typically we would recommend a certain type of actuator based on what you tell us you're using it for, but for those of you who are just tuning in, see below for common applications for various types of actuators and see if you can pick your project out.
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Track Actuators - Used for tight spaces where a sliding block is ideal due to its unchanging retracted and extended length.
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Rod-Style Actuators - These are the most common actuators you will find, and simply feature a shaft which extends and retracts, providing linear motion.
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Feedback Actuators - For applications which have systems to read the actuators' position, these potentiometer pod equipped actuators are ideal; they provide accurate information for precise control over your application.
Now that you know how much force you need, and an idea of what type of actuator you require, we can move on to the next step of determining what stroke length you'll be wanting.
How long should an Actuator be?
Here is where most people get slightly miss-informed. The difference between the open and closed position for an actuator is simply known as the 'stroke length'. For example, if we had a to move a sliding block twelve inches, we would want to make sure that the actuator we chose for the job would have a stroke length of at least twelve inches.
Do I need a High Speed Actuator?
So to re-cap: You know now how much force you need, as well as the type of actuator you'll be using and the stroke length. Finally you are now ready to figure out the speed of the actuator. Most of the product lines found on our site feature several different forces, this is important because within those product lines, as you increase in force, you decrease in speed due to varying gear ratios, much like the transmission in a car. So by now you've narrowed your selection down to one or maybe two product lines that we carry. At this point, it is a good idea to go to the 'Specifications' tab of each unit and have a look at their speed rating. Keep in mind, speed ratings are assuming the unit is being used at full load.
You're now equipped with the thought process that the pro's in large scale engineering projects follow on a daily basis. If you have further questions or concerns, you will find a wealth of helpful staff at the ready via email or phone on our contact page.
Watch Videos and Read Articles on Linear Actuators Below
