Standard Ball Srews  Manufacturers, Traders, Suppliers

Ball screws (hereinafter also KGT) are construction elements of drives which convert rotary motion into linear motion with high efficiency (they are not self-locking) and are characterized by high rigidity, accuracy and service life.

For the production of precision ball screws, steels of the quality ČSN 14 260, CF53 or 42CrMo4 (shafts) and 14 109 or 14 209 (nuts) are used. The nuts and the threaded part of the spindle are case-hardened and reach a hardness of 58-60 HRC. The core and non-hardened parts of the shaft have a minimum strength of Rm = 650 MPa.

The KGT are used in the following areas and applications of industrial production:

• Processing and Forming Machines
• Injection moulding machines
• Packaging machines
• Lifting devices
• Handling and automation technology
• Medical technology
• Pharmaceutical industry (medical and laboratory equipment)
• Automotive industry, aviation industry etc.

Ball Screw: Comprehensive Technical Documentation 1. Introduction to Ball Screws A **ball screw** is a high-precision mechanical component designed to convert rotational motion into linear motion (or vice versa) with minimal friction. Unlike traditional lead screws that rely on sliding contact, ball screws use recirculating steel balls to transfer force, resulting in significantly higher efficiency, accuracy, and service life. They are widely adopted in industrial automation, robotics, machine tools, and aerospace applications where precise linear positioning, high load capacity, and low maintenance are critical requirements.
2. Working Principle The core principle of a ball screw lies in the **recirculation of steel balls** between the screw shaft and the nut. Here’s a step-by-step breakdown of its operation: 1. The screw shaft features a helical groove (raceway) that matches the profile of the steel balls. 2. The nut, which encloses the screw shaft, contains a corresponding helical groove and a ball recirculation system (e.g., end caps or deflector tubes). 3. When the screw shaft rotates (or the nut rotates), the steel balls roll along the helical raceways, converting the rotational motion into linear displacement of the nut (or shaft). 4. After reaching the end of the nut’s raceway, the balls are guided back to the starting point via the recirculation system, creating a continuous loop. This rolling contact design reduces friction coefficient to as low as 0.001–0.005 (compared to 0.1–0.3 for sliding lead screws), enabling high efficiency (typically 90–95%) and minimal wear. ## 3. Key Components A standard ball screw assembly consists of four main components, each playing a vital role in performance:
3.1 Screw Shaft
Material: Typically made of high-strength alloy steel (e.g., SUJ2, SCM440) with heat treatment (quenching and tempering) to achieve a surface hardness of HRC 58–62, ensuring wear resistance and load capacity.
- Groove Profile: The helical groove (raceway) is precision-ground to a Gothic arch or circular arc profile, optimizing ball contact and load distribution.
- Lead: The distance the nut travels linearly with one full rotation of the screw shaft (measured in mm or inches). Common lead values range from 1 mm to 100 mm, with custom leads available for specific applications.
3.2 Nut - Structure: The nut houses the helical raceway (matching the screw shaft) and the ball recirculation system. It is often made of the same alloy steel as the screw shaft (or brass for light-load applications) and undergoes surface hardening.
Recirculation Systems:
End Cap Type: Plastic or metal end caps at the nut’s ends redirect balls from the end of the raceway back to the start, suitable for high-speed applications (up to 5 m/s).
Deflector Tube Type: Metal tubes inside the nut guide balls through a separate channel, ideal for high-load applications and easy maintenance.
Internal Circulation Type: Balls recirculate within the nut’s body via internal grooves, offering compact design but lower speed capacity.
3.3 Steel Balls - Material: High-carbon chromium bearing steel (e.g., SUJ2) with precision grinding to G10–G20 grade (diameter tolerance ±0.001 mm), ensuring uniform size and smooth rolling.
Lubrication: Balls require continuous lubrication (grease or oil) to reduce friction and prevent corrosion. Specialized lubricants with anti-wear additives are recommended for extended service life.
3.4 Accessories - Support Units: Bearings (e.g., angular contact ball bearings) mounted at the screw shaft’s ends to absorb radial and axial loads, ensuring stable rotation.
Dust Seals: Lip seals or wiper rings attached to the nut’s ends to prevent dust, debris, and coolant from entering the raceway, critical for harsh industrial environments.
Locknuts: Used to secure the screw shaft to the support units, preventing axial movement and ensuring positioning accuracy.
4. Types of Ball Screws Ball screws are classified based on design, installation, and performance to meet diverse application needs:
4.1 Based on Mounting Configuration - **Fixed-Fixed (FF)**: Both ends of the screw shaft are fixed with support units (e.g., double angular contact bearings). Offers the highest rigidity and critical speed, suitable for long shafts (length-to-diameter ratio> 20) and high-speed applications. - Fixed-Supported (FS): One end fixed, the other end supported by a radial bearing. Balances rigidity and thermal expansion compensation, ideal for medium-length shafts (length-to-diameter ratio 10–20).
-Free-Supported (FS): One end supported, the other end free. Low rigidity, used for short shafts (length-to-diameter ratio < 10) and light-load applications.
4.2 Based on Lead Accuracy - C0 Class: Ultra-high precision (lead error ±0.003 mm/300 mm), used in semiconductor manufacturing and optical equipment.
C1 Class**: High precision (±0.005 mm/300 mm), suitable for CNC machine tools and robotics. - C3 Class**: Standard precision (±0.012 mm/300 mm), common in industrial automation and general machinery.
C5/C7 Classes: Economic precision (±0.023/±0.050 mm/300 mm), used in low-cost linear motion systems.
4.3 Based on Nut Design
Single-Nut Ball Screws: Compact design, suitable for applications with limited space. However, they have no preload adjustment, so backlash (axial play) may occur under light loads.
- Double-Nut Ball ScrewsTwo nuts mounted on the same screw shaft, with a preload mechanism (e.g., spacer, offset grinding) to eliminate backlash. Ideal for high-precision positioning (e.g., CNC milling machines) where zero backlash is required.
5. Performance Parameters When selecting a ball screw, the following parameters must be evaluated to ensure compatibility with the application:
5.1 Load Capacity - **Dynamic Load Capacity (C): The maximum axial load the ball screw can withstand for 1 million rotations without fatigue failure (measured in kN). Calculated based on the screw diameter, lead, and number of balls. -
Static Load Capacity (C0): The maximum axial load that can be applied without permanent deformation (typically 2–3 times the dynamic load capacity). Critical for applications with static or low-speed loads.
5.2 Speed and Critical Speed - **Maximum Rotational Speed**: The highest speed the ball screw can operate without excessive heat or vibration (depends on the lead, lubrication, and cooling system).
Critical Speed (Nc): The rotational speed at which the screw shaft resonates (causes severe vibration). Calculated using the formula: \( Nc=\frac{10^6 imes E imes d^4}{3.5 imes L^2 imes m} \) (Where \( E \)=Young’s modulus, \( d \)=shaft diameter, \( L \)=unsupported length, \( m \)=mass per unit length). To avoid resonance, the operating speed should be < 80% of \( Nc \). ### 5.3 Accuracy and Backlash
Lead Accuracy The deviation between the actual linear travel and the theoretical travel (specified by ISO standards, e.g., ISO 3408). Higher accuracy classes (C0, C1) are required for precision positioning.
Backlash: The axial play between the screw shaft and the nut (measured in mm). For single-nut designs, backlash is typically 0.01–0.05 mm; for double-nut designs with preload, backlash can be reduced to < 0.005 mm (or even zero).
5.4 Service Life -
L10 Life**: The number of rotations (or linear travel) at which 90% of ball screws will operate without fatigue failure. Calculated using the formula: \( L10=\left( \frac{C}{P} ight)^3 imes 10^6 \) (Where \( C \)=dynamic load capacity, \( P \)=actual axial load). Service life can be extended by proper lubrication, dust protection, and avoiding overloading.
6. Application Fields Ball screws are widely used in industries requiring high precision, efficiency, and reliability:
6.1 Industrial Automation - **Linear Actuators**: Used in robotic arms, conveyor systems, and pick-and-place machines to achieve precise linear motion. - **Packaging Machinery**: Ensure accurate positioning of packaging materials (e.g., filling nozzles, sealing heads) for consistent product quality.
6.2 Machine Tools - **CNC Milling/Lathing Machines**: Provide high-speed, high-precision linear feeds for cutting tools, enabling tight tolerances (±0.001 mm) in metalworking. - **Grinding Machines**: Deliver smooth, vibration-free motion for precision grinding of components (e.g., bearings, gears).
6.3 Robotics - **Industrial Robots**: Used in joint actuators and linear axes to achieve precise movement (e.g., welding robots, assembly robots). - **Medical Robots**: Enable ultra-precise positioning in surgical robots (e.g., laparoscopic robots) and diagnostic equipment (e.g., CT scanners).
6.4 Aerospace and Defense - **Aerospace Components**: Used in aircraft landing gear systems, satellite positioning mechanisms, and missile guidance systems, where high reliability and resistance to extreme environments (temperature, vibration) are critical. - **Military Equipment**: Applied in tank turret positioning, artillery aiming systems, and unmanned aerial vehicle (UAV) actuators.
6.5 Medical Equipment - **Diagnostic Machines**: Ensure precise movement of detectors in MRI, X-ray, and ultrasound machines. - **Rehabilitation Devices**: Provide controlled linear motion in prosthetics and physical therapy equipment (e.g., robotic exoskeletons).
7. Installation and Maintenance Guidelines Proper installation and maintenance are essential to maximize the performance and service life of ball screws:
7.1 Installation Best Practices
1. Shaft Alignment: Ensure the screw shaft is perfectly parallel to the linear guideway (if used) to avoid radial loads, which can cause premature wear. Use a laser alignment tool to check parallelism (tolerance < 0.1 mm/m).
2. Support Unit Mounting: Secure the support units firmly to the machine frame to prevent vibration. Use torque wrenches to tighten bolts to the manufacturer’s recommended torque values.
3. Nut Mounting: The nut should be mounted to the moving component (e.g., slider) with minimal eccentricity. Avoid applying radial or moment loads to the nut, as this can damage the raceway. 4. Lubrication Before Operation**: Apply the recommended lubricant (grease or oil) to the screw shaft and nut raceway before initial operation. Ensure full coverage of the steel balls and raceway.
7.2 Maintenance Procedures 1. **Regular Lubrication**: Reapply lubricant every 100–500 operating hours (or as per the manufacturer’s guidelines). For high-speed or high-load applications, use oil lubrication with a forced lubrication system.
2. Dust and Debris Removal**: Clean the screw shaft and nut with a soft brush or compressed air (low pressure) every week to remove dust, chips, and coolant. Replace dust seals if they show signs of wear (e.g., cracks, deformation).
3. Backlash Inspection: Check backlash quarterly using a dial indicator. If backlash exceeds the acceptable range (e.g.,> 0.01 mm for precision applications), adjust the preload (for double-nut designs) or replace the nut.
4. Vibration and Noise Monitoring: Monitor the ball screw during operation for abnormal vibration or noise, which may indicate misalignment, worn components, or insufficient lubrication. Address issues immediately to prevent further damage.
5. Periodic Disassembly and Inspection: For critical applications, disassemble the ball screw annually to inspect the steel balls, raceway, and recirculation system. Replace worn components (e.g., balls, end caps) and regrind the screw shaft if there is excessive wear.
8. Troubleshooting Common Issues | Issue | Possible Causes | Solutions | Excessive Backlash | 1. Worn steel balls or raceway
2. Loose preload (double-nut designs)
3. Nut or shaft misalignment | 1. Replace steel balls or nut
2. Adjust preload (add spacer or grind nut)
3. Realign nut and shaft | | Abnormal Noise/Vibration | 1. Insufficient lubrication
2. Misalignment of support units
3. Worn bearings in support units
4. Resonance (operating speed > critical speed) | 1. Reapply lubricant
2. Realign support units
3. Replace bearings
4. Reduce operating speed or increase shaft diameter | | Reduced Efficiency | 1. Contaminated raceway (dust, debris)
2. Corroded steel balls or shaft
3. Overloading (exceeding dynamic load capacity) | 1. Clean raceway and replace dust seals
2. Replace corroded components and apply anti-corrosion lubricant
3. Reduce load or select a ball screw with higher load capacity | | Nut Jamming | 1. Foreign objects in the raceway
2. Damaged recirculation system (end caps/tubes)
3. Severe misalignment | 1. Disassemble and remove foreign objects
2. Replace damaged recirculation components
3. Realign nut and shaft |
9. Market Trends and Future Developments The global ball screw market is driven by the growth of industrial automation, robotics, and aerospace industries. Key trends include:
9.1 Miniaturization With the increasing demand for compact equipment (e.g., medical devices, micro-robots), manufacturers are developing miniaturized ball screws with diameters as small as 2 mm and leads as low as 0.5 mm. These mini ball screws feature lightweight materials (e.g., titanium alloys) and precision machining to maintain high accuracy.
9.2 High-Speed and High-Load Capacities Advancements in material science (e.g., use of ceramic balls instead of steel balls) and heat treatment technologies are enabling ball screws to operate at higher speeds (up to 10 m/s) and withstand higher loads (up to 1000 kN). Ceramic balls offer lower density, higher hardness, and better corrosion resistance than steel balls, making them ideal for high-performance applications.
9.3 Smart Ball Screws Integration of sensors (e.g., load sensors, temperature sensors, position sensors) into ball screws enables real-time monitoring of performance parameters (e.g., load, temperature, backlash). This data can be transmitted to a central control system for predictive maintenance, reducing downtime and improving reliability. Smart ball screws are increasingly used in critical applications such as aerospace and medical equipment.
9.4 Environmental Sustainability Manufacturers are focusing on developing eco-friendly ball screws by using recyclable materials (e.g., recycled steel) and reducing lubricant consumption (e.g., self-lubricating coatings). Additionally, energy-efficient designs (e.g., low-friction raceway profiles) are being adopted to reduce power consumption in automation systems.
10. Conclusion Ball screws are essential components in modern mechanical systems, offering high precision, efficiency, and reliability for linear motion applications. By understanding their working principle, key components, performance parameters, and maintenance requirements, engineers can select and use ball screws effectively to optimize system performance. With ongoing advancements in miniaturization, high-speed technology, and smart monitoring, ball screws will continue to play a critical role in the future of industrial automation, robotics, and aerospace industries. For specific application requirements or custom designs, it is recommended to consult with ball screw manufacturers or technical experts to ensure the selection of the most suitable product.

• Double-Nut Ball ScrewsTwo nuts mounted on the same screw shaft, with a preload mechanism (e.g., spacer, offset grinding) to eliminate backlash. Ideal for high-precision positioning (e.g., CNC milling machines) where zero backlash is required.

Application Fields of Ball Screws
Ball screws are a critical mechanical component that converts rotational motion into linear motion with high efficiency, precision, and low friction. Their unique design, which incorporates recirculating balls between the screw shaft and nut, makes them indispensable in a wide range of industries where accuracy, reliability, and energy efficiency are paramount. Below is a detailed exploration of the key application fields where ball screws play a vital role.
1. Industrial Automation
In the realm of industrial automation, ball screws are the backbone of countless mechanical systems, enabling precise and repeatable motion control. They are extensively used in CNC (Computer Numerical Control) machines, such as milling machines, lathes, and machining centers. In these devices, ball screws drive the movement of the tool or workpiece along the X, Y, and Z axes, ensuring that cuts and shaping operations are executed with micron-level accuracy. This high precision is essential for manufacturing complex components used in industries like automotive, aerospace, and electronics.
Additionally, ball screws are integral to robotic arms and automated assembly lines. Robots rely on ball screws to achieve smooth and precise linear movements, whether it's picking and placing components, welding, or packaging. The low friction of ball screws allows robots to operate with minimal energy consumption, while their high load-carrying capacity ensures they can handle heavy payloads, making them ideal for high-volume production environments.
2. Precision Instrumentation
The field of precision instrumentation demands components that can deliver ultra-high accuracy and stability, and ball screws meet these requirements exceptionally well. They are widely used in metrology equipment, such as coordinate measuring machines (CMMs) and optical comparators. CMMs use ball screws to move the measuring probe along three axes, allowing for precise measurements of part dimensions and geometries. The ability of ball screws to maintain consistent motion without backlash ensures that measurement results are reliable and accurate, which is crucial for quality control in industries like medical device manufacturing and semiconductor production.
Ball screws also find applications in laboratory equipment, including centrifuges, spectrometers, and automated sample handlers. In centrifuges, for example, ball screws control the movement of the rotor or sample holders, ensuring that samples are processed at precise speeds and positions. In automated sample handlers, they enable the precise transfer of samples between different stations, reducing the risk of human error and improving the efficiency of laboratory operations.
3. Transportation Industry
The transportation industry leverages the high performance and durability of ball screws in various applications. In automotive manufacturing, ball screws are used in robotic systems for welding, painting, and assembly, as mentioned earlier. They also play a role in the design of electric and hybrid vehicles, where they are used in the steering system and suspension components. The precise linear motion provided by ball screws helps improve the handling and stability of vehicles, while their low friction contributes to energy efficiency.
In the aerospace and defense sector, ball screws are critical components in aircraft and spacecraft. They are used in the flight control system, where they drive the movement of ailerons, elevators, and rudders, ensuring precise control of the aircraft's flight path. Ball screws are also used in the landing gear system, where they can withstand high loads and harsh operating conditions, such as extreme temperatures and vibrations. In spacecraft, they are used in the deployment of solar panels, antennas, and other payloads, requiring high reliability and precision to ensure successful missions.
4. Medical Equipment
The medical industry relies on ball screws for their precision, cleanliness, and reliability, as they are often used in equipment that directly impacts patient health. They are commonly found in surgical robots, which assist surgeons in performing minimally invasive procedures. Surgical robots use ball screws to control the movement of the surgical instruments, allowing for precise and delicate operations with minimal tissue damage. The high precision of ball screws ensures that the instruments can be positioned with sub-millimeter accuracy, reducing the risk of complications and improving patient outcomes.
Ball screws are also used in medical imaging equipment, such as CT scanners, MRI machines, and X-ray systems. In CT scanners, for example, ball screws drive the movement of the gantry and the patient table, ensuring that the scanner can capture high-quality images of the body. The smooth and precise motion of ball screws helps reduce image artifacts, improving the accuracy of diagnostic results. Additionally, ball screws are used in rehabilitation equipment, such as robotic exoskeletons, which help patients recover from injuries by providing controlled and repetitive movement.
5. Energy Sector
In the energy sector, ball screws are used in a variety of applications that require reliable and efficient motion control. In wind turbines, they are used in the pitch control system, which adjusts the angle of the turbine blades to optimize power generation based on wind speed. The ball screws in the pitch control system must withstand high loads and harsh environmental conditions, such as strong winds and extreme temperatures, while maintaining precise control of the blade angle. This ensures that the wind turbine operates efficiently and safely, maximizing energy output.
Ball screws are also used in solar power systems, particularly in solar trackers. Solar trackers use ball screws to move the solar panels so that they follow the sun's path throughout the day, increasing the amount of sunlight absorbed and improving the efficiency of the solar power system. The low friction and high efficiency of ball screws make them ideal for this application, as they can operate with minimal energy consumption, even in remote locations.
Conclusion
In conclusion, ball screws are a versatile and essential component that finds applications in a wide range of industries, from industrial automation and precision instrumentation to transportation, medical equipment, and the energy sector. Their ability to provide high precision, efficiency, and reliability makes them indispensable in modern manufacturing and technology. As industries continue to demand higher levels of accuracy and performance, the role of ball screws is only expected to grow, driving innovation and advancements in various fields.