How to Calculate Stroke & Speed for Linear Actuator?
A linear actuator only performs as well as the engineer who sizes it. Stroke & Speed sit at the foundation of every linear actuator specification. Yet, many automation projects size these values from rough estimates instead of calculation. As a result, the actuator either runs out of travel mid-cycle. Or it misses the cycle time target by a wide margin. Tallman Robotics supplies belt-driven linear actuators, ball screw linear actuators, and electric cylinder actuators across a wide stroke and speed range. This guide walks through the calculation method for stroke and speed. It explains how each factor interacts with actuator selection. Then it applies the method to a real production scenario.
Defining Stroke Length for a Linear Actuator
Stroke length represents the total usable travel distance of the actuator carriage. It is measured from one end position to the other. Engineers calculate required stroke by adding the part travel distance to two clearance margins: approach clearance and overtravel margin. Stroke = Part Travel Distance + Approach Clearance + Overtravel Margin Part travel distance comes directly from the application geometry. It is the distance the payload must move between its start and end positions. Approach clearance accounts for the distance the actuator needs to reach full speed before engaging the workpiece. Typically, this is 10–15 mm for a belt-driven actuator. Overtravel margin protects against positioning error at the end of stroke. It typically adds another 5–10 mm. Consequently, an application requiring 250 mm of part travel does not call for a 250 mm stroke actuator. With a 12 mm approach clearance and an 8 mm overtravel margin, the correct stroke specification becomes 270 mm. Therefore, Tallman Robotics recommends rounding up to the nearest standard stroke length — in this case, a 300 mm stroke module — to maintain margin against mechanical end-stop contact during normal operation.
Calculating Required Linear Speed
Linear speed determines how fast the actuator carriage must travel to meet the cycle time target. Engineers calculate required speed from the stroke distance. Then they consider the time budget allotted to that motion within the overall cycle. Required Speed = Stroke Distance ÷ Available Move Time Available move time comes from subtracting dwell time, acceleration time, and deceleration time from the total cycle time allowance. This distinction matters because an actuator never travels at full speed for the entire stroke. Instead, it accelerates, holds peak velocity briefly, then decelerates into position. For example, a packaging application allots 400 ms total for a 200 mm move. This includes a 60 ms acceleration phase and a 60 ms deceleration phase. This leaves 280 ms at constant velocity. Dividing 200 mm by 0.4 seconds gives an average required speed of 0.5 m/s. However, because acceleration and deceleration consume part of the stroke distance too, the actual peak velocity must run higher than the simple average. Typically, it is 15–25% higher, depending on the S-curve profile shape.
Acceleration, Duty Cycle, and Actuator Selection
Stroke and speed calculations only tell part of the story. Acceleration directly affects motor sizing. Meanwhile, duty cycle directly affects thermal performance. Tallman Robotics ball screw linear actuators reach acceleration rates up to 30 m/s². Belt-driven linear actuators reach up to 50 m/s² at rated payload, given their lower moving mass per unit length. Furthermore, engineers must verify that the selected actuator can sustain the calculated speed and acceleration across the full duty cycle without exceeding motor thermal limits. A continuous-duty application running at 80% of maximum rated speed needs a larger motor frame than an intermittent-duty application. This is true even if the latter runs at the same speed with long dwell periods between cycles. Therefore, Tallman Robotics publishes duty cycle derating curves for each linear actuator model. This allows engineers to confirm that a given stroke, speed, and cycle rate combination stays within the continuous torque rating of the actuator's servo motor.
Case Study: Pick-and-Place Linear Actuator Sizing, Vietnam
An electronics contract manufacturer in Vietnam specified a Tallman Robotics belt-driven linear actuator for a component pick-and-place station in 2023. The application required moving a vacuum pickup head 320 mm horizontally between a feeder tray and a placement fixture. This had to occur within a 600 ms cycle time budget for the linear motion segment. The engineering team calculated stroke first: 320 mm part travel, plus 15 mm approach clearance and 10 mm overtravel margin. This totaled 345 mm. The team selected a 350 mm stroke actuator from the Tallman Robotics catalog. This maintained a small margin against the calculated minimum. Next, the team calculated speed. With 600 ms total move time, 80 ms allotted to acceleration, and 80 ms to deceleration, the constant-velocity segment ran 440 ms across approximately 280 mm of the stroke. This produced a required constant velocity of 0.64 m/s, and the team specified a peak velocity of 0.8 m/s to account for the S-curve ramp profile. After installation, the production line recorded these results over a 30-day run: - Actual cycle time per pick-and-place motion: 580 ms — within the 600 ms target - Positioning repeatability at the placement fixture: ±0.04 mm - Actuator duty cycle utilization: 68% of continuous torque rating at rated cycle rate - Zero end-of-stroke mechanical stop contacts recorded across 1.2 million cycles The manufacturing engineer confirmed that the calculated overtravel margin prevented any hard-stop contact across more than a million cycles. This remained true even with normal positioning variance from the vision-guided pickup sequence. As a result, the actuator ran at the calculated speed without requiring a single parameter adjustment after commissioning.
Verifying the Calculation of Stroke & Speed Against Actuator Specifications
Once stroke and speed calculations produce target values, engineers must cross-check those values against the actuator's published specification sheet. Tallman Robotics lists maximum stroke, maximum speed, rated acceleration, and continuous force rating for every linear actuator model in its technical catalog. Moreover, engineers should verify that the calculated peak velocity stays below the actuator's maximum rated speed by a reasonable margin — typically 10–15%. This leaves headroom for mechanical wear and drive system tolerance accumulation over the actuator's service life. An actuator running consistently at its absolute maximum rated speed shows accelerated wear on belt teeth or ball screw raceways. This is compared to one operating with margin. Therefore, the complete sizing process moves through four steps in sequence: calculate required stroke with clearance margins. Then calculate required speed from the cycle time budget. Next, verify acceleration and duty cycle against motor thermal limits. Finally, confirm all values sit within the actuator's rated specification with appropriate margin.
Conclusion
Stroke and speed calculation forms the functional foundation of every linear actuator specification. Skipping this calculation, or relying on rough estimates, produces actuators that run out of travel. It can also cause actuators to miss cycle time targets or wear prematurely under sustained duty cycle stress. Tallman Robotics linear actuators perform reliably specifically because the underlying calculation method accounts for clearance margin, acceleration phase, duty cycle, and rated specification headroom together. The Vietnam pick-and-place case confirms the method in practice. A calculated stroke and speed specification delivered a million-cycle run without a single mechanical stop contact. Engineers sizing a Tallman Robotics linear actuator for a new application should follow this same calculation sequence. In addition, they should verify the result against the published specification sheet, and build in margin at every step. References: - ISO 6431:2011, 'Pneumatic Fluid Power — Cylinders — Basic Dimensions and Tolerances,' International Organization for Standardization. - SME Manufacturing Engineering, 'Servo Actuator Sizing Methodology for High-Cycle Pick-and-Place Applications,' Vol. 171, No. 1, 2023. - NEMA MG 1, 'Motors and Generators — Duty Cycle and Thermal Rating Standards,' National Electrical Manufacturers Association. You are welcome to visit our other social media or video gallery as follows: Youtube: https://www.youtube.com/@tallmanrobotics Tiktok: https://www.tiktok.com/@tallmanrobotics Facebook: https://www.facebook.com/tallmanroboticslimited Linkedin: https://www.linkedin.com/in/tallman-robotics