Spend enough time trying to motorise something and the actuator question will find you. It doesn’t matter if it’s a machine component, a piece of industrial equipment, or something you’ve built from scratch. The options multiply fast, the specs get dense, and a wrong choice typically means pulling everything apart and starting again. Sorting it out properly from the beginning is worth the effort.
This guide walks through the factors that actually matter when choosing an actuator. It’s aimed at engineers, builders, and anyone technically minded who wants a practical framework, not a product recommendation.
Start with what the actuator actually needs to do
The worst way to start is by browsing product listings. Before any of that, get specific about the job. Force requirements, motion type, operating speed, environment, duty cycle. These vary so much between applications that two projects can look superficially similar and need completely different solutions. Nailing down each variable upfront is what separates a good selection from an expensive guess.
Work through these before you look at anything else: What type of motion does the application need? Linear, rotary, or both? What force or torque does it have to generate? How quickly does it need to move? How often will it run, and for how long each time? What conditions will it be operating in? Heat, cold, moisture, dust, vibration?
Once you have clear answers, evaluating products becomes straightforward. Without them, you’re just comparing numbers that may or may not be relevant to what you’re actually building.
Linear vs rotary: the first decision
Most selection processes start here. Linear actuators produce straight-line motion, pushing or pulling along a single axis. Rotary actuators produce angular or circular motion around a fixed point.
Linear actuators are the right call when you need to extend, retract, lift, lower, push, or pull something in a straight line. They’re common in medical equipment, industrial machinery, agricultural equipment, and custom automation builds. Stroke length and load capacity are usually the primary design constraints.
Rotary actuators are for anything that needs to turn, pivot, or rotate. You’ll find them in robotics, valve control systems, and anywhere a joint or hinge needs powered movement.
Where an application needs both types working together, multi-axis systems are the answer. For most projects though, pinning down which type of motion is required is enough to cut the field in half before you’ve looked at a single product page.
Force and load requirements
This is where a lot of people underspec. The temptation is to estimate the load, find an actuator that covers it, and move on. The problem is that real-world applications almost always involve more force than the static load alone.
Dynamic loading, friction, acceleration, mounting angle, and safety margins all add to the actual force demand. As a starting point, build in at least 25 to 30 percent above your calculated requirement. Where shock loads or unpredictable force spikes are part of the picture, that buffer needs to be larger.
Push force and pull force are also worth keeping separate. A lot of linear actuators are rated differently in each direction, and selecting based on the wrong figure leads to accelerated wear or failure under load.
Speed, stroke, and duty cycle
These three specs interact with each other in ways that aren’t always obvious.
Stroke length is the total distance the actuator travels from fully retracted to fully extended. It needs to match your mechanical requirements with some precision. Too short and it won’t complete the movement. Too long and you get mechanical interference and wasted mounting space.
Speed is typically expressed in millimetres per second for linear actuators. Faster isn’t always the right call. When you push for higher speed, force output tends to drop. Motor torque and output force trade off against each other for a given power input, so if the application genuinely needs both, a larger and more powerful unit is the answer.
Duty cycle is the one that catches most people out. It describes how long the actuator can run within a given period before heat becomes a problem. Take a 25% duty cycle rating as an example: the actuator can run for 15 seconds out of every minute before thermal damage becomes a risk. If your application runs the actuator frequently or for extended periods, this spec needs to be part of the conversation from the start, not an afterthought.
Environmental considerations
An actuator that’s well matched on force and motion can still fail quickly if the operating environment doesn’t suit it.
IP rating tells you how well the unit is protected against dust and moisture ingress. IP54 covers basic splashing and dust exposure. For anything involving washdown conditions, sustained outdoor use, or direct water contact, IP66 or higher is the appropriate starting point. The temperature range is worth checking separately. Most standard actuators are rated for typical indoor use, and outdoor or industrial settings can push well outside that band. Never assume a unit will cope with conditions outside its rated range.
Corrosion resistance is its own consideration and shouldn’t be confused with IP rating. In marine or chemical environments, the housing material and any exposed fasteners or fittings need to be chosen for the specific exposure. Stainless steel hardware or additional protective coatings are worth specifying wherever corrosion is a real risk rather than a theoretical one.
Power supply and control interface
Actuator selection doesn’t end with the mechanical specs. How the unit receives power and responds to control signals determines how well it fits into the broader system.
Most electric linear actuators run on either 12V or 24V DC. The 24V option generally handles longer cable runs more cleanly and tends to perform more consistently under load. At high force demands, current draw can spike significantly, so the power supply needs to be rated for peak conditions rather than average use.
A basic two-wire switch works fine when all you need is for the actuator to move from one position to another. When the application calls for something more precise, analog feedback, PWM speed control, and closed-loop position sensing give you accurate, repeatable control throughout the actuator’s travel range. Match the control method to what the job actually needs rather than defaulting to the most complex option available.
Before committing to a specific unit, verify it works with your existing control hardware. Most manufacturers publish wiring diagrams and control specifications, so checking compatibility before you buy is usually straightforward.
Mounting and mechanical integration
Even a well-specified actuator will cause problems if the mounting hasn’t been thought through. Clevis, flange, trunnion, and rod-end mounts each suit different configurations. Whichever style you use, the attachment points need to align properly with the load direction. Any misalignment puts side loads on the actuator body and rod, and that kind of stress adds up quickly in service.
Where the actuator operates through a changing angle as it extends, the mount needs to allow the unit to follow that movement. Locking it in place rigidly forces bending stress into the rod, which isn’t what it’s designed to carry. Units installed that way tend to fail well before they should.
A selection checklist worth keeping
When evaluating any actuator for a specific application, working through these in order tends to catch most mismatches before they become problems:
- Motion type required (linear or rotary)
- Force or torque requirement with appropriate safety margin
- Stroke length or rotation angle
- Required speed at rated load
- Duty cycle for the intended use pattern
- Environmental rating and temperature range
- Power supply voltage and available current
- Control interface compatibility
- Mounting style and mechanical integration
- Lead time and availability if procurement timelines matter