A THK ball screw is a high-precision linear motion device that converts rotational motion into linear motion with minimal friction. It consists of a screw shaft and a nut with recirculating steel balls that reduce contact friction. THK is a globally renowned Japanese manufacturer known for producing highly reliable, accurate, and durable ball screws for use in machine tools, robots, and precision equipment. Often paired with THK Linear Guideways (LM Guides), THK ball screws form the core of precise linear drive systems. How Does a THK Ball Screw Work? THK ball screws operate on the principle of rolling motion rather than sliding. Inside the nut, a series of precision steel balls roll between the screw shaft and the internal thread of the nut, forming a ball bearing raceway. These balls recirculate continuously through return channels or tubes, allowing for: High motion efficiency (≥ 90%) Low starting torque High repeatability and positioning accuracy Main Components of a THK Ball Screw Screw Shaft – Precision-machined steel shaft with helical grooves. Nut (Ball Nut) – Contains matching internal grooves and houses the rolling balls. Steel Balls – Move within the grooves to transmit motion and reduce friction. Ball Recirculation System – Guides balls back into the raceway for continuous movement. End Seals & Lubrication Ports – Prevent contamination and ensure long life. Key Features of THK Ball Screws ✅ High Efficiency Over 90% efficiency, which reduces energy consumption. ✅ Low Friction Rolling elements reduce heat and wear compared to lead screws. ✅ High Positioning Accuracy Ideal for applications requiring micron-level motion control. ✅ Backlash Elimination Options Preloaded nuts reduce backlash for improved precision. ✅ Smooth Operation Ball movement ensures vibration-free and quiet performance. ✅ High Rigidity Optional double nuts or larger diameters enhance rigidity under load. ✅ Interchangeability Standardized dimensions allow easy replacement and servicing. Types of THK Ball Screws 1. Precision Ball Screws Manufactured with ground threads for high accuracy (C0–C5 grades). Used in CNC machines, medical equipment, and high-end automation. 2. Rolled Ball Screws Less expensive with formed threads (C7–C10 accuracy). Suitable for general industrial automation and non-critical tasks. 3. DIN/ISO Metric Ball Screws Standardized for global compatibility. 4. High-Speed Ball Screws Designed for rapid linear motion with optimized ball circulation. 5. Ball Screws with Caged Ball Technology Reduces noise and vibration. Prevents ball-to-ball contact, enhancing lubrication and lifespan. THK Ball Screw Accuracy Grades Grade Lead Error (μm/300mm) Application C0 ±3 Ultra-high precision instruments C1 ±5 Semiconductor, medical equipment C3 ±8 CNC machining centers C5 ±23 General machinery C7 ±52 Automation, transport stages C10 ±210 Low-precision movement Popular THK Ball Screw Models Model Description Features BNK Compact ball screw Ideal for miniaturized devices BIF Ball screw with integrated support unit Easy installation WGF High-speed, low-noise Caged Ball design BNT High load, large lead Designed for fast movement Applications of THK Ball Screws 🔧 CNC Machine Tools – Lathes, milling machines, EDMs 🤖 Robotic Actuators – Linear movement in arms and gantries 📐 Precision Measuring Devices 🏗 Industrial Automation Systems 🩺 Medical Equipment – Scanners, surgery robots 📦 Packaging & Assembly Lines 🖨 3D Printers & Plotters 🎯 Aerospace Guidance Systems Advantages of THK Ball Screws Over Lead Screws Feature THK Ball Screw Lead Screw Efficiency ~90% ~30% Friction Very Low Higher Accuracy Micron-grade Lower Lifespan Long Shorter Backlash Minimal (with preloading) High Maintenance Less frequent More often Installation & Maintenance Tips Always mount with aligned axes to prevent eccentric wear. Preload carefully if using dual nuts. Use proper lubrication (THK offers its own lubricants). Clean surrounding area to prevent contamination of ball return systems. Conclusion THK Ball Screws deliver world-class performance for precision linear motion systems. Their advanced features—like caged ball technology, high efficiency, and minimal backlash—make them ideal for high-speed, high-accuracy industrial and automation applications. When combined with THK LM Guides, they offer a complete and reliable linear motion solution.