# Top Actuator Tips for Design Engineers - Choosing the Right Electric Linear Actuator

Nathan Bong
PA Engineer

Finding the most suitable electric linear actuator for your application can be challenging, especially when there are so many different variables to consider. Knowing your application requirements and having a detailed understanding of the available actuator solutions and their capabilities is critical during the designing stages of a project. This is because choosing the best linear actuator for a specific use case will ensure optimal operation to yield the best possible results. In this article, we will cover the top actuator tips for design engineers to choose the right electric linear actuator for an application.

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## Tips to Consider When Choosing Electric Linear Actuators

Linear actuators are commonly used as the driving force to provide linear motion in many different applications and industries. From a designer’s perspective, there are quite a few things to consider when choosing an electric linear actuator for the optimum application results. Below are our top tips for finding the most suitable actuator solution:

• Calculate how much force you need
• Find the suitable travel speed
• Check the physical dimensions
• Consider environmental protection requirements
• Decide between standard or track actuators
• Figure out the application’s duty cycle
• Determine what feedback you may need
• Verify if there were any noise restrictions
• Perform physical tests on your actuator

### Calculate How Much Force You Need

The force rating of an actuator refers to the maximum amount of force that the actuator can push/pull (dynamic) and hold (static). Factors that can affect how much force is exerted onto an actuator include:

• Uneven weight distribution
• Actuators not perpendicular to the motion of the moving object
• Relative position of the actuator to the center of mass
• Wind resistance and other load disturbances

Calculating the force that will truly be exerted onto an actuator helps to confirm which models have sufficient ratings for the application. Industrial actuators have a heavy-duty design for applications that require a high force rating.

### Find the Suitable Travel Speed

The right travel speed ensures an actuator can travel to a given position in the required amount of time. If an application experiences heavier loads at different times or occasional voltage drops, the actuator’s speed will slow down. Because of this, it is also important to factor in the load and voltage applied so that the true speed during operation will be within your application requirements. Since speed ratings are only valid when actuators are under optimal conditions, applications that have precise speed requirements will require speed control capabilities.

### Check the Physical Dimensions

Before installation, it is important to check if a given space can accommodate an actuator’s length, width, and height. An actuator’s retracted hole to hole (H2H) dimension is the first crucial measurement when determining its physical requirements. This measurement is the distance from the center of the rear mounting hole to the center of the front mounting hole. It is essential to make sure that this dimension lines up with your application’s rear mounting hole center to the front mounting hole center. Micro actuators offer a compact size for smaller-scale applications that have limited installation space.

### Consider Environmental Protection Requirements

Linear actuators come with an International Protection Marking (IP) rating to indicate their ability to withstand liquid and dust intrusion. Choosing actuators with a suitable IP rating mitigates the risk of water damage and solids from reaching the internal components. Waterproof linear actuators are recommended for applications that will be submerged or exposed to a lot of water. When possible, mounting an actuator with the stroke end pointing downwards is generally the best practice if there is any risk of water exposure. This way, gravity will pull liquid away from the motor housing and help prevent premature failure.

An IP rating does not test for weather or corrosion resistance during seasonal changes and long periods (e.g., years outside during multiple seasons). Therefore, consider the environment you are going to use the actuator in to make sure it is suited for that environment. Progressive Automations offers various certifications besides the IP rating. These certifications could be requirements that may apply to your application. Speak to us if you require specific certifications for your actuator and/or application.

### Decide Between Standard or Track Actuators

Standard actuators are designed with extending rods that are enclosed in a sealed housing; however, a track linear actuator’s range of motion is enclosed in a track. This makes a track style design more sensitive to dust and water, however, a track system offers a pre-defined path to increase the amount of structural support experienced when fully loaded. By being able to handle more force than an equivalent traditional device of the same size, track actuators are more efficient and affordable solutions for indoor applications that already required a fixed vertical or horizontal motion.

### Figure Out the Application’s Duty Cycle

The duty cycle of a linear actuator is the ratio of on-time and off-time and is expressed as a percentage. It is common for standard actuators with a brushed DC motor to have a 20% duty cycle that is based on a period of 20 minutes. At a 20% duty cycle, linear actuators can run continuously for 4 minutes and then needs to rest for 16 minutes. Anything over 20 minutes at a 20% duty cycle will risk damaging the motor due to overheating. Choosing an actuator with the appropriate duty cycle is incredibly important to ensure the motor does not experience burnout during operation. To achieve a 100% duty cycle for continuous operation, you will require a brushless DC motor.

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### Determine What Feedback You May Need

Certain applications and pre-existing systems may require actuators with a specific type of feedback to work correctly. Determining an actuator’s position is useful for applications that require multiple actuators to travel at the same speed, store preset positions, and/or collect positional information for user analysis. When selecting an actuator, ensuring that it has suitable feedback is important for compatibility with your system. In electric linear actuators, there 3 major types of positional feedback:

1. Potentiometer feedback
2. Hall effect sensor feedback
3. Limit switch feedback

#### Potentiometer Feedback

Potentiometers make mechanical contact with the gears that rotate inside the actuators. Because potentiometers are just voltage dividers with a large resistor, they are good at dealing with electromagnetic interference (EMI). The biggest advantage of this type of feedback is its simplicity for applications that need quick drop-in solutions, while not requiring as much accuracy or high precision.

Built-in potentiometer feedback

#### Hall Effect Sensor Feedback

Hall effect sensors provide electrical pulses when the magnet is aligned with sensing electronics. For this reason, they are suitable for high-speed applications and allow to pre-program certain motor shaft angles. With no need to make any contact, they are useful in harsh environments, highly resistant to wear and tear, and reliable in high shock environments. This feedback option is best suited for applications that require reliability, precision, and long life.

Built-in Hall effect sensor feedback

#### Limit Switch Feedback

The purpose of limit switch feedback signals is to allow a system to determine whether the actuator has physically tripped the internal limit switches. This kind of feedback is simple and useful for applications that mainly just require information on whether the actuator has reached the fully extended or fully retracted positions.

Limit switch feedback

### Verify If There Were Any Noise Restrictions

Consumer-facing applications such as automated doors, hatches, or levers inside coffee machines may have certain noise restrictions. To verify if an actuator was within the required noise levels, perform tests in a quiet environment with a decibel meter held close to the linear actuator as it extends and retracts. A decibel chart can help you gauge if the noise level from an actuator falls within a range that suits your application.

 Decibel Level Sound type Decibel Level0 Sound typeNearly Silent Decibel Level15 Sound typeWhispering Decibel Level60 Sound typeNormal conversation Decibel Level90 Sound typeLawnmower Decibel Level110 Sound typeCar Horn Decibel Level120 Sound typeLive Rock Concert Decibel Level140 Sound typeFirecrackers

### Perform Physical Tests on Your Actuator

Once you have considered an actuator for your application, the next step is to run physical tests on the unit to verify if it will be a long-term solution. Calculations and theoretical analysis are good points of reference; however, real-world tests are the most accurate way to determine if your actuator solution was the best choice. Our Free Actuator Testing Guide covers all the recommended tests in detail such as bench testing, lab testing, and field testing to help you find the best actuator for your application: