Electric Cylinder Lifetime Calculation: How Is It Calculated, What Does It Depend On?
The question of how long an electric cylinder will last is often asked long after the purchasing decision — when a failure actually occurs. Yet lifetime is a predictable value that can be calculated in advance during the design phase using a few parameters. In this article, we explain how lifetime calculation is done, which parameters change the result, and the real factors that shorten lifetime in the field.
Simple approach: lifetime based on stroke and cycle count
At the most basic level, lifetime is the ratio of the ball screw's total revolution capacity to the number of revolutions made in one cycle:
Cycle Life = Total Revolution Capacity / (Stroke × Number of Directions)
Here, "Number of Directions" refers to how many times direction changes within one cycle (in most applications, 2 — back and forth). The shorter the stroke, the more cycles the same total revolution capacity gets divided into — meaning short-stroke, high-frequency applications (packaging, pick-and-place) wear out "more expensively" per cycle compared to long-stroke, infrequent-cycle applications.
This calculation is sufficient to give a quick initial idea, but it's not sufficient on its own — because it doesn't account for load.
The real engineering approach: L10 life
For ball screws, as with bearings, the industry standard is the L10 life calculation (ISO 3408). Since the cylinder operates under varying loads throughout a cycle rather than a single constant load, the cubic mean load (Fm) is used instead of actual loads:
Fm = ³√[ (F1³×d1 + F2³×d2 + ... + Fn³×dn) / (d1+d2+...+dn) ]
Each segment (acceleration, constant speed, deceleration, return) is weighted by its own force and the distance it covers. This gives a much more realistic result than a constant-load assumption — especially in applications where the load rises momentarily during acceleration/braking phases.
L10 life is calculated as follows:
L10 (revolutions) = (Ca / Fm)³ × 10⁶
Ca is the screw's dynamic load capacity (a catalog value). This revolution count is divided by the lead to get the total distance traveled, which is then divided by the typical cycle length to convert it into an expected number of cycles.
Four main factors affecting lifetime
1. Load — Due to the cubic relationship, a small increase in load causes a disproportionate drop in lifetime. Increasing the load by 25% can roughly cut lifetime in half.
2. Speed and acceleration — High speed by itself doesn't shorten lifetime, but the additional load during acceleration/braking phases (F = m×a) pulls the overall cubic mean upward. Harsh start-stop profiles reduce lifetime noticeably more than smooth profiles.
3. Cycle frequency and stroke length — As seen in the simple formula above, short-stroke, high-frequency cycles consume the total capacity faster.
4. Environment and maintenance — Dust, high temperature, and chemical exposure degrade the lubrication film, increasing friction and thus the effective load. Regular lubrication and proper guide adjustment are prerequisites for approaching the catalog lifetime — a poorly maintained system can fall far short of the lifetime calculated on paper.
How is this used in practice
For correct model selection, lifetime calculation should be done together with torque and speed calculation — because the same force and stroke produce different lifetime results with different lead/gearbox combinations. You can do a preliminary assessment by entering your application's load, speed, and cycle data into our own calculation tool, and contact our engineering team for final model selection.
This article describes a general methodology; the L10 life value for a specific model should be calculated using that model's catalog Ca value and your application's actual load profile.