How To Select a Linear Actuator in 6 Steps

Are you a machine builder evaluating different types of linear actuators for your project? When it comes to automating motion, linear actuators are essential in a wide range of industries, from manufacturing and robotics to medical devices and aerospace and more. With so many different types of linear actuators available, how do you know which one is right for your application? 

Making the wrong choice could be a costly mistake, whereas selecting the right actuator could lead to higher throughput and a faster time-to-market. This article explores six simple steps to guide your decision when selecting a linear actuator that is right for your application.

1. Satisfy Thermal Requirements

Thermal requirements for linear actuators refer to the specific temperature ranges and heat dissipation capabilities needed to ensure optimal performance, prevent overheating, and maintain durability during operation. Overheating can cause an actuator to stop functioning, or worse, damage itself and its environment. Evaluating thermal performance is a complex process that considers the forces the actuator must generate, the duty cycle of those forces, efficiency of the actuator and its ability to dissipate heat. These factors, combined with other considerations like force, speed, and environment, play an essential role in ensuring your actuator operates within safe temperature limits.

2. Force Required

Force refers to the amount of power an actuator can exert to perform a task. An application's force requirements are dependent on several factors, such as the mass of a system and amount of friction it generates, both static and dynamic. The mass of the system being moved combined with acceleration requirements are one important factor. Even light-weight systems that require very high accelerations might require quite high forces from the actuator. On the other hand, a heavy system (with low friction) that does not need fast accelerations might require less force. In vertical applications, where the system moves against gravity, the actuator must exert greater force for upward motions and less force for downward motions. ORCA^TM Series Smart Linear Motors offer a range of forces depending on your product's needs, from 40.8 lbf/182 Newtons to maximum forces of 238 lbf/1061 Newtons. 

3. Speed Required

The rate at which the actuator’s moving element travels along its stroke length, typically measured in inches per second (in/s) or millimeters per second (mm/s). High-speed actuators are ideal for applications requiring rapid motion, such as automated systems or robotics, while lower speeds may be necessary for applications demanding precise control or high force output. Generally, the more force required the less speed the actuator will be able to reach, there’s often a trade-off. Tubular linear motors, such as ORCA motors, are known for their rapid actuations, exceeding several meters per second.

4. Precision & Control

The ability for the actuator to achieve and maintain an accurate position, speed, and force with minimal deviation ensures optimal performance, reliability, and precision across a wide range of applications. This is typically achieved by feeding the measured position into a controller, which then drives the actuator. Position can be measured in a number of ways and the precision of the resulting system depends on several factors These include the method of position measurement, the resolution of the drive mechanism, the nature of the system being driven, and the operating speed of the controller. High precision is important for applications requiring exact positioning like CNC machines, robotics, or medical devices. Electric linear actuators offer excellent precision and fine control allowing for accurate adjustments in position, speed, and force. ORCA motors offer the above benefits, all with integrated sensors, drivers, and controllers for feedback. 

5. Stroke Length

The maximum distance an actuator can travel in a single direction. It directly affects the range of motion in an application—longer stroke lengths allow for more extensive movement, while shorter strokes are suitable for tasks requiring limited motion, such as high frequency applications. Electromechanical actuators offer the most flexibility, with an essentially unlimited range of stroke lengths and precise control for a wide variety of applications. Essentially unrolled servomotors, linear motors generate force that moves along a stationary magnet track, in theory, this track can extend to any desired length. 

6. Environment

Environmental factors like temperature, humidity, and contamination play a key role in actuator performance. Electric actuators are less affected by environmental conditions and work well in most environments, though extreme temperatures can impact electronics. Pneumatic actuators are sensitive to moisture which can cause corrosion or performance issues, so they're best suited for controlled and dry environments. Hydraulic actuators are vulnerable to contamination in the hydraulic fluid requiring proper sealing and maintenance, especially in dirty or outdoor settings where dust and moisture can degrade performance. It’s important to evaluate the environment in which you’re operating in and ask yourself, is the application indoor or outdoor, what are the temperature and cleanliness requirements, is it susceptible to corrosion, etc. Consider IP protection ratings required for your actuator. ORCA motors are IP68 rated, meaning they are completely dustproof and waterproof - watch an ORCA motor operate 100 feet (30.5 m) underwater.  

Further Considerations

• Repeatability: The ability of the actuator to consistently return to a specific position within a defined tolerance after repeated movements. This is a critical factor in high accuracy applications like labeling or dispensing.
• Load Capacity: Refers to the maximum force the actuator can effectively support during operation. This is dependent on factors such as the motor's design, magnetic strength, and the application's speed, acceleration, and duty cycle requirements.
• Duty Cycle: The proportion of time the motor operates under load compared to the total cycle time. Determines whether the motor can sustain continuous operation, or requires intermittent use to prevent overheating or performance degradation.  
• Total Cost of Ownership (TCO): The TCO of a linear motor encompasses not just the initial purchase price but also long-term expenses such as installation, maintenance, energy consumption, and potential downtime. Linear motors often have higher upfront costs but can offer lower TCO due to their efficiency, minimal maintenance requirements, and long operational lifespan. In comparison to pneumatic systems, electric linear motors offer significant upfront cost reductions. 

Innovations in Linear Actuation

Time spent purchasing, integrating, and calibrating individual components of linear motors themselves take away from the time required to develop the overall system. By streamlining the assembly process and significantly reducing commissioning time, integrated motor systems enable you to focus on what truly matters—advancing your project. Iris’s ORCA’ series smart linear motors come with a pre-calibrated servo drive, position controller, and force sensing technology directly within the motor body, allowing you to plug and play. Pre-calibration mitigates the risk of error by ensuring precise synchronization and optimal performance of all components, from the start. With a fully-integrated solution, reap the benefits of faster deployment times, reduced downtime, and a more streamlined development process.