Actuator for Automated Testing Equipment Guide: How to Spec

You need a test rig that presses, pulls, cycles, or positions a sample the same way every time. An actuator for automated testing equipment gives that rig controlled linear motion, so you can set stroke, force, speed, and feedback instead of relying on hand operation. Start with load, friction, acceleration, and cycle rate before you pick the actuator.

What is an actuator for automated testing equipment?

An actuator for automated testing equipment is an electric linear drive that moves a fixture, probe, platen, latch, switch, or sample carrier during a repeatable test. It replaces hand motion with controlled extension and retraction.

Simple Explanation

Think of the actuator as the repeatable hand in the test rig. It must push or pull hard enough, travel far enough, move at the right speed, and report position when the test needs repeatable data.

Use the formula below to calculate the minimum actuator force for a guided linear test fixture.

F_req = (F_test + μ × W + W × a ÷ g) × SF

The formula treats W as the moving weight the actuator sees along the guide, not the full machine weight. For clean linear guides, start with SF = 1.5. Use SF = 2.0 or higher when the fixture has shock loads, poor alignment, dirty rails, or hard stops.

When do you use this actuator calculation?

You use this calculation when you need a fixture to repeat a press, pull, lift, slide, latch, clamp, or positioning test without operator variation. The calculation matters at the point where sample force, moving fixture weight, guide friction, and test cycle time all meet.

Miss the force and the rig stalls. Miss the speed and your test no longer matches the real application. Miss the feedback requirement and your data drifts after a few cycles.

For a wider selection workflow, start with our linear actuator selector. If your fixture includes pivots, off-center loading, or a lifting arm, compare your hand math with the linear actuator calculator.

Suitable Applications

Automated testing equipment usually needs modest stroke, controlled motion, and repeatable setup more than raw force. The actuator choice changes when the fixture tests a switch, compresses foam, pulls a latch, or cycles a sliding assembly.

• Appliance push-button and rocker-switch cycle testers.
• Laptop hinge, small door, and access panel life-cycle rigs.
• Automotive latch, pedal, HVAC flap, and console mechanism endurance fixtures.
• Packaging dispenser, pump, and spring-return force tests.
• Medical device plunger and cap actuation fixtures for engineering validation.
• Robotics gripper, end-effector, and clamp cycle rigs.
• RV slide-out, drawer-slide, and cabinet lift prototype testers.
• CNC machine guard, door, and small linear mechanism endurance rigs.

Each application needs the same 4 checks: force, stroke, speed, and control method. If the test also records position, add feedback and calibration to the list.

How does the actuator test loop work?

A basic test loop has 5 parts: the actuator, guided fixture, sample, controller, and measurement device. The controller commands extension, the actuator moves the fixture, the fixture loads the sample, and the measurement device records position, force, time, current, or pass/fail state.

The mechanical guide carries side load. The actuator should only push or pull along its centerline. If you ask the actuator rod to act like a linear rail, the rod sees bending load, friction rises, and repeatability drops fast.

For feedback-driven rigs, the controller also needs a homing routine. Homing gives the test a repeatable zero point before cycle counting or position moves begin.

Which motion formulas matter after force?

Force keeps the actuator from stalling. Stroke and speed keep the test valid. Start with the move time your test needs, then calculate the speed.

v = S ÷ t_move

Cycle count also matters, especially in endurance testing. A vague target like run all day gives you nothing to size against. Turn it into cycles per day.

C_day = (3600 × H) ÷ t_cycle

These formulas do not replace the actuator datasheet. They give you the shortlist before you check exact force, speed, stroke, duty cycle, mounting, and feedback details.

How should you think about feedback and controls?

For automated testing equipment, feedback often matters more than it does in a simple lift. If the rig only runs full extend to full retract against internal limits, a standard actuator can work. If the rig needs a 2.35-inch press depth, a repeatable midpoint, or synchronized motion, you need feedback and a controller that can use it.

Hall Effect and optical systems usually give your controller pulse signals. In many actuators, the sensor reads rotating gearbox or encoder-disc movement, not direct rod travel. Hall sensors read alternating magnetic poles on a rotating disk. Optical sensors read light pulses through slots in a rotating disk.

From the controller point of view, Hall and optical feedback both usually behave like pulse systems. Controller compatibility depends on voltage, wiring, pulse type, pulse count, direction handling, and calibration. Read Feedback from a Hall Effect Sensor With Video and Integrating Optical Feedback Actuators with PLC and Arduino if your fixture uses pulse feedback.

Potentiometer feedback works differently. It gives an analog position voltage from a wiper and resistive track tied to actuator travel. That analog voltage does not measure actuator force, side load, or mechanical binding. For the analog side, see Potentiometer Feedback from a Linear Actuator With Video and Linear Actuator Feedback Devices: Potentiometers vs Encoders.

For a broader sensor comparison, use Feedback Options for Linear Actuators and Electric Linear Actuators with Feedback Sensors. If your test measures force rather than position, read Load Feedback in Linear Actuators Guide: Sense Force Safely.

Simple Example

Given: F_test = 25 lbs, W = 12 lbs, μ = 0.15, a = 0 in/s², SF = 1.5.

F_req = (25 + 0.15 × 12 + 0) × 1.5 = 40.2 lbs.

Pick at least a 45 lb actuator, then check stroke, speed, feedback, mounting, and duty cycle.

How do you size an actuator for a foam compression cycle tester?

Let’s size a simple lab fixture that compresses a foam sample with a guided platen. The test needs 75 lbs of compression force, 6 inches (152 mm) of actuator travel, and a 10-second extension stroke.

Inputs: F_test = 75 lbs, W = 20 lbs, μ = 0.10, a = 10 in/s², g = 386 in/s², SF = 1.5.

Substitution:

F_req = (75 + 0.10 × 20 + 20 × 10 ÷ 386) × 1.5

F_req = (75 + 2 + 0.52) × 1.5 = 116.28 lbs

Round up to 117 lbs minimum. Do not pick a 110 lb actuator for this fixture unless the exact configuration gives enough margin at the required speed and duty cycle. The 1.5 safety factor already helps, but real fixtures still punish tight sizing.

Now calculate speed:

v = 6 in ÷ 10 s = 0.6 in/s

If the full cycle takes 25 seconds and the rig runs 8 hours per day:

C_day = (3600 × 8) ÷ 25 = 1152 cycles/day

The Utility Linear Actuator range covers 110 to 330 lbs, 0.25 to 1.0 in/s, 2 to 12 inches of stroke, IP66, Hall Effect feedback, and synchronization compatibility. That range fits this example better than a no-feedback actuator when the test needs position data. Verify the exact variant before you build the fixture.

Which actuator system should you choose?

Electric actuators solve many automated test fixtures cleanly, but they do not replace every motion system. Use the table below to choose the right hardware type before you spend time on brackets and controls.

Related FIRGELLI Products

Use this table as a product shortlist. The final choice still needs exact force, speed, stroke, feedback, mounting, and duty-cycle checks.

Mounting hardware changes repeatability. Source data lists the MB1-P Mounting Bracket for P-series Actuator as a base end bracket for the Utility Linear Actuator. For Super Duty Actuators, the MB17 Mounting Bracket For Super Duty Actuators supports clevis or end mounting.

If you want to compare the full actuator range before narrowing the test rig, browse our linear actuators collection.

What goes wrong when you spec the actuator incorrectly?

The most common failure starts with side load. If the fixture pushes off-axis, the rod bends slightly, guide friction rises, and the actuator current climbs. Use external linear guides and let the actuator provide thrust, not guidance.

Undersized force causes stalls near peak load. Oversized speed can hit the sample too hard and change the test. Loose clevis joints add backlash, which makes small position tests look worse than the actuator really performs.

Timed motion without feedback can drift when load, temperature, friction, or supply voltage changes. If the test needs partial-stroke accuracy, use feedback and calibrate the controller against the actual fixture travel.

What should you check before buying?

Use this 6-point check before you select an actuator for automated testing equipment:

1. Calculate force with sample load, moving weight, friction, acceleration, and SF.
2. Set stroke from real fixture travel, then add room for mounting adjustment.
3. Calculate required speed from move time, not from a guess.
4. Decide whether the test needs no feedback, pulse feedback, or analog feedback.
5. Use linear guides when the fixture creates side load.
6. Confirm brackets, IP rating, wiring, controller inputs, and cycle rate before production use.

FAQ

About the Author

Robbie Dickson is the Chief Engineer and Founder of FIRGELLI Automations. With a background in aeronautical and mechanical engineering through Rolls-Royce, BMW, and Ford, he has spent over 2 decades designing precision motion control systems, from linear actuators for robotics to active aerodynamic braking systems for supercars. For this application, the rule stays simple: size force first, then stroke, speed, feedback, cycle rate, and mounting.