Functions and Characteristics of Ball Screws in CNC Machine Tools

1. Main Functions of Ball Screws in CNC Machine Tools
 
1.1、High-Precision Motion Conversion
 
The core function of the ball screw is to convert the rotary motion of the motor into linear feed motion with zero backlash and low loss, ensuring that the movement distance of the coordinate axis is highly consistent with the command value. In precision machining, the accuracy of the screw directly affects the dimensional accuracy, geometric tolerances, and surface finish of parts, serving as the foundation for micron-level machining.
 
1.2、Ensuring Positioning Accuracy and Repeat Positioning Accuracy
 
CNC machine tools have extremely high requirements for position control. Ball screws eliminate axial clearance through precision raceways and preloading structures, eliminating reverse backlash during reciprocating movement of the worktable. This ensures minimal errors after repeated positioning, meeting the consistency requirements of mass production.
 
1.3、Transmitting Power and Bearing Loads
 
The screw must withstand axial forces and overturning moments generated by the worktable, workpiece, fixture, and cutting process. It must transmit power smoothly while maintaining structural rigidity under heavy-duty and high-speed conditions without deformation or vibration.
 
1.4、Enabling High-Speed and Stable Feeding
 
Modern CNC machine tools are developing toward high speed and high efficiency. Ball screws support high feed rates and rapid movement while ensuring smooth, shock-free motion. This prevents chatter marks during cutting and guarantees the machining quality of complex surfaces and precision cavities.
 
1.5、Improving Transmission Efficiency and Energy Saving
 
Traditional sliding screws have high friction and low efficiency. In contrast, ball screws operate on rolling friction, greatly reducing power loss, lowering motor load and heat generation, and improving response speed and long-term operational stability.
 
2. Core Characteristics of Ball Screws
 
2.1、Extremely High Transmission Efficiency
 
Ball screws use a ball rolling structure with a transmission efficiency of 90%~98%, much higher than the 20%~30% of ordinary sliding screws. Under the same load, less driving torque is required, allowing the use of lower-Power Servo Motors, saving energy and reducing costs.
 
2.2、High Motion Accuracy and Zero Backlash
 
Through structures such as double-nut preloading and single-nut modified lead preloading, zero-backlash transmission can be achieved with no lost motion during reverse movement. Positioning accuracy can usually reach ±0.001 mm or higher, meeting the requirements of high-precision CNC equipment.
 
2.3、Smooth Motion, No Low-Speed Crawling
 
Rolling friction resistance is small and uniform. Even at extremely low feed speeds, the "low-speed crawling" common in sliding screws does not occur, ensuring uniform and stable motion suitable for fine cutting and hard cutting.
 
2.4、Long Service Life and High Reliability
 
The raceway surface is treated with high-hardness quenching and precision grinding, providing high hardness and wear resistance. With proper lubrication and maintenance, the service life is several times that of ordinary sliding screws, making it suitable for long-term continuous operation.
 
2.5、Excellent Reversible Transmission
 
It can convert rotary motion to linear motion and vice versa smoothly, enabling fast start-stop and high dynamic response for machine axes, adapting to high-speed and high-precision machining commands.
 
2.6、High Rigidity and Strong Load Capacity
 
Optimized and precisely assembled ball screws feature high axial rigidity with minimal deformation under cutting forces and gravity. They maintain stable accuracy under heavy loads, suitable for mold machining and heavy cutting.
 
2.7、Relatively Simple Maintenance
 
Special grease or Lubrication Systems reduce wear and heat generation. Sealing structures prevent cutting fluid and dust from entering the raceway, reducing failure rates and adapting to harsh industrial environments.