Ball Screw vs. Belt Drive Linear Modules: How to Choose
Ball screw and timing belt drives are the two most common choices for single-axis linear modules. Both can carry a load on a guided carriage, but they behave very differently in accuracy, speed, stroke length and stiffness. This guide explains the differences and gives a short checklist for choosing between them.
Short answer
- Choose a ball screw module when you need high positioning accuracy, high thrust, a stiff axis or a vertical axis, and the stroke is moderate (up to about 1 m).
- Choose a timing belt module when you need long stroke, high speed and fast cycles with light to medium loads, and ±0.04 mm repeatability is enough.
- For strokes beyond 3 m or heavy loads, look at rack and pinion modules; for the highest dynamics and accuracy, at linear motor modules.
How each drive works
In a ball screw module, the motor turns a precision screw. A ball nut fixed to the carriage converts the rotation into linear motion. The lead (travel per revolution) sets the relationship between motor speed and carriage speed: with a 3000 rpm servo motor, a 10 mm lead gives 500 mm/s, a 20 mm lead 1000 mm/s.
In a timing belt module, the motor drives a pulley, and a toothed belt attached to the carriage pulls it along the profile. Each revolution moves the carriage by the pulley circumference, typically 40 mm or more, so belt modules reach high speeds at moderate motor speeds.
Comparison with real module data
The values below are taken from two HS LINEAR modules with the same 140 mm body width, so the drive type is the only major difference.
| Ball screw – BSS140 | Timing belt – BTS140 | |
|---|---|---|
| Repeatability | ±0.01 mm | ±0.04 mm |
| Max. speed | 250 / 500 / 1000 / 1600 mm/s (lead 5 / 10 / 20 / 32 mm) | 2000 mm/s |
| Payload | up to 110 kg | up to 35 kg (horizontal) |
| Standard stroke | 100–1050 mm | 100–3050 mm |
| Recommended servo | 400 W | 400 W |
Payload and speed always depend on mounting direction, acceleration and stroke. Check the curves and tables on the product page for your case, or send us your data.
Where ball screw modules are better
- Accuracy and stiffness. The screw is rigid in the direction of travel, so the carriage holds its position under process forces such as pressing, dispensing or screw driving.
- Vertical axes. With a motor brake, a ball screw axis holds the load safely when power is off. This is why Z axes in gantry and cantilever systems are usually ball screw driven.
- High thrust at low speed. A small lead multiplies the motor torque into high axial force.
The limit is stroke and speed: a long, slender screw starts to whip at high rotational speed (critical speed). For long strokes the maximum speed must be reduced, or a different drive used.
Where timing belt modules are better
- Long stroke. Belt length does not limit speed the way screw length does, so strokes of several metres are possible.
- High speed and short cycle times. Pick-and-place, transfer and packaging axes benefit from 2 m/s travel speed.
- Low moving mass and quiet running.
The trade-off: the belt is elastic, so stiffness and repeatability are lower, and a belt axis should not be used vertically without a brake and careful safety design.
Checklist for your selection
- Required repeatability – better than ±0.02 mm: ball screw or linear motor.
- Stroke – over about 1 m: belt, rack and pinion or linear motor.
- Speed and cycle time – above 1.5 m/s: belt or linear motor.
- Load and mounting – heavy or vertical loads: ball screw (vertical) or rack and pinion (long and heavy).
- Process forces – pressing or machining forces on the carriage: ball screw.
- Environment – dust or chips: consider fully enclosed ball screw or fully enclosed belt designs.
Many multi-axis systems combine both: a belt-driven long X axis for travel and a ball screw Z axis for accurate, braked vertical motion. See our multi-axis systems and the guide Gantry, cantilever or moving-arm: how to choose.
Frequently asked questions
Is a ball screw always more accurate than a belt?
In repeatability, yes in most cases: ±0.01 mm for the BSS140 compared with ±0.04 mm for the BTS140. Absolute accuracy over the full stroke also depends on the screw grade, guide rails and mounting surface.
Can a belt-driven module move vertically?
It is possible with a brake motor and low loads, but a belt can stretch or break, so we usually recommend a ball screw axis for vertical motion.
Which lead should I choose for a ball screw module?
Choose the smallest lead that still reaches your required speed. A smaller lead gives more thrust and finer resolution; a larger lead gives more speed. For the full calculation see How to size a linear module.
Need help choosing?
Send us the load, stroke, speed, required accuracy and mounting direction. We will recommend a suitable module and send a drawing for review. Contact us or browse the ball screw and timing belt linear modules.
