Machine inefficiencies, backlash, and wear cause lost precision, downtime, and high costs. Ball screws eliminate these issues with low friction, stiffness, and durability—driving reliable linear motion.

Ball screws convert rotational motion into precise linear movement using rolling elements, offering high accuracy, repeatability, and efficiency across automation, CNC, and robotics applications.

Read on to discover why ball screws outperform other linear motion solutions.

What is a ball screw?

A ball screw is a precision mechanical linear actuator that translates rotational motion into linear motion with minimal friction. Unlike lead screws where sliding occurs, ball screws use steel ball bearings to roll between threads, drastically reducing energy loss and wear.

Structure includes a threaded shaft (normed by lead and pitch) and a matching nut containing recirculating balls. As the screw rotates, balls circulate through the nut via return channels. This rolling mechanism allows near-unity mechanical efficiency (often 90%+), enabling high-speed motion with reduced heat and backlash.

Ball screws are widely used in CNC machinery, robotics, high-precision assembly, and linear motion stages, offering advantages in repeatability, load capacity, and control.

Components of ball screws

A ball screw consists of several precision-engineered components working together to deliver smooth, accurate linear motion:

• Screw Shaft: Helically threaded rod made of hardened steel. Thread lead (distance balls travel per revolution) determines mechanical resolution.

• Nut: Contains internal thread and recirculating path for steel balls; solid or split ring types are available.

• Balls: Hardened steel or ceramic spheres that roll between shaft and nut, carrying the load.

• Ball Return System: Internal passages or external tubes guide balls continuously through the nut.

• End Fittings: Seals, wipers, or covers to protect from dust, debris, and lubrication loss.

• Preload System: Applied by nut design to eliminate axial backlash and stiffen the assembly.

• Lubrication Network: Grease or oil applied through ports, ensuring longevity and reducing friction.

Each component contributes to the precision, stiffness, and lifespan of a ball screw assembly. Quality machining, heat treatment, and assembly processes are critical to performance.

Accuracy of ball screws

Accuracy is a primary strength of ball screws, defining how well their actual motion follows commanded motion.

• Lead Accuracy: Deviation over a single thread turn. Common grades include C0 (≤2 μm/300 mm), C5, C7, etc. Higher accuracy grades cost more but are essential for machine tool tables and metrology systems.
• Backlash: Axial play between nut and shaft. Achieved using precision preload (e.g., Class II preload gives ≤5 µm). Low backlash is vital for bidirectional motion and CNC repeatability.
• Repeatability: Ability to return to a point accurately. Ball screws typically have ±1 µm repeatability under proper preload and control.
• Straightness & Rotation Error: Shaft straightness and concentricity ensure smooth operation without binding or vibration.

These metrics are standardized (ISO 3408, JIS B1192) to help engineers specify ball screws suited for applications like servo-driven CNC axes, robotics, or precision assembly modules.

Types of ball screws

There are several ball screw types, each tailored to different industrial needs:

1. Standard Ball Screw

Ground or rolled shaft paired with nut and return tubes. Ideal for general motion systems with moderate precision.

2. Miniature Ball Screw

Compact screws with diameters ≤10 mm and fine threads—used in consumer electronics, surgical robots, and small lab modules.

3. High-Precision Ball Screw

5‑axis CNC, laser cutters, aerospace systems—requires ultra-high grades like C0 or C3, low clearance, and rigid mounting.

4. Preloaded Double Nut Ball Screw

Two nuts preloaded against each other eliminate backlash and stiffen the system—great for vertical axes and servo applications.

5. Roller or Planetary Ball Screw

Uses rollers instead of balls for high-load, low-speed axes—found in heavy industrial presses and lifting systems.

6. Acme-Like Hybrid Ball Screw

Combines acme threads with internal ball bearings to achieve intermediate precision and load capacity at reduced cost.

Selection depends on load, precision, speed, life expectancy, and space constraints.

Advantages of ball screws

Ball screws offer clear benefits over other mechanical linear drives:

• High Efficiency: Rolling motion reduces friction to 10% of acme screws—improves energy use and reduces heat.

• High Precision & Repeatability: Micron-level accuracy supports CNC, robotics, semiconductor, optical applications.

• Load Handling: High dynamic and static loads with long fatigue life.

• Minimal Backlash: Preloading removes play for precise bidirectional positioning.

• Long Service Life: Hardened steel, lubrication, and preload maximize durability.

• Compatibility with Motors: Excellent pairing with servo/stepper motors—supports high-speed, closed-loop feedback systems.

• Noise Reduction: Quieter operation due to rolling mechanism.

Overall, ball screws produce safer, more reliable, and cost-effective motion compared to low-efficiency sliding mechanisms.

Comparison of ball screws and lead screws

Ball screws outperform lead screws in high-load, high-speed, or high-precision scenarios. However, lead screws remain cost-effective for low-load, occasional motion systems.

Summary

Ball screws deliver unmatched precision, efficiency, and load performance—ideal for high-performance linear motion across industries.For further questions please contact sales@limonrobot.com