Ball screw is a mechanical transmission device used to convert rotary motion into linear motion. It is commonly used in various CNC machine tools, mechanical equipment and automation systems. Calculating the torque of a ball screw requires considering the following factors: 1. Input torque: Input torque is the external torque acting on the ball screw. It can be provided by the driving force, which can be a motor or other power device. The input torque is transmitted to the output through the ball system of the ball screw. 2. Ball screw transmission efficiency: The transmission efficiency of the ball screw is usually above 90%, which may vary depending on the specific ball screw type and usage conditions. The higher the transmission efficiency, the smaller the difference between output torque and input torque. 3. Ball screw dynamic parameters: The dynamic parameters of the ball screw include pitch, lead and ball diameter. Pitch refers to the distance the ball screw moves axially during one revolution of the nut. Lead refers to the angle of rotation required for a ball screw to move axially for one revolution. Ball diameter refers to the diameter of the balls used in the ball screw. Generally speaking, the following formula can be used to calculate the torque of a ball screw: Torque = (input torque × transmission efficiency) / (pitch × 2π) Among them, the input torque and transmission efficiency are known parameters, the pitch represents the axial movement distance of the ball screw, and 2π represents the rotation angle of one revolution. Please note that the units in the above formula must be consistent, for example, the unit of torque is Newton·meter (N·m) and the unit of pitch is meter (m). It should be noted that the torque calculation of the ball screw is a simplified model. In actual applications, some other factors may need to be considered, such as the loading conditions of the ball screw, friction and wear, etc., which may affect the torque. When designing and selecting a ball screw, it is recommended to refer to the relevant ball screw design manual or consult a professional engineer for more accurate calculation methods and parameter selection.

Here is Shuntai’s answer for you: Ball screw and nut assemblies in CNC machine tools are key components used to transmit rotational motion and convert it into linear motion. The ball screw is a mechanical transmission device composed of a screw and a ball nut. Its working principle is to engage the threads on the screw with the balls on the ball nut, and drive the ball nut to move axially along the screw during rotation. There are many balls inside the ball nut. These balls roll in the ball groove, which can reduce friction resistance, improve transmission efficiency, and have high rigidity and positioning accuracy. Ball screws are widely used in CNC machine tools, automation equipment, precision machinery and other fields. The nut is a component used with the ball screw and is usually made of metal material. The nut has internal threads that match the ball threads and mate with the ball screw threads. When the ball screw rotates, the nut moves along the screw axis, achieving linear motion. The design and processing quality of the nut have an important impact on the accuracy and life of the ball screw transmission. Ball screw and nut assemblies are often used in the feed system and positioning system of CNC machine tools to ensure that the machine tool has high stability, positioning accuracy and fast performance during processing. Their use can improve the processing efficiency and accuracy of machine tools, while reducing friction and wear between moving parts and extending the service life of machine tools. If you have any other questions, please contact us. Thank you for reading. Thank you.

Preload adjustment of ball screws is a key step to ensure their high precision, high rigidity and long life. The role of preload is to eliminate the gap between the ball and the raceway, reduce the reverse clearance (backlash), and improve the axial rigidity and vibration resistance of the system. However, excessive preload may cause heating, increased wear and even jamming, so the adjustment must strictly follow the technical specifications. The following are the detailed methods and precautions for preload adjustment: 1. Purpose of preload adjustment Eliminate axial clearance: Ensure that the screw has no empty stroke when moving forward and backward. Improve rigidity: Enhance the system's ability to resist deformation due to load changes. Extend life: Reasonable preload can evenly load the ball and avoid local wear. Reduce vibration and noise: Reduce impact and abnormal noise caused by clearance. 2. Main methods of preload adjustment a. Double nut preload method (most common) Principle: Apply opposite axial forces through two nuts to squeeze the ball into contact with the raceway. Steps: Install double nuts: Install two ball nuts in reverse on the same screw shaft. Apply preload: rotate the two nuts to bring them closer together, compress the elastic element in the middle (such as a disc spring) or directly lock them through the thread. Adjustment method: Torque control method: tighten the nut to the specified torque value with a torque wrench (refer to the manufacturer's data). Displacement control method: measure the distance between the two nuts and adjust to the preset compression amount (usually 1%~3% of the lead). Lock the nut: use a locking washer or thread glue to fix the adjusted position. b. Shim adjustment method Applicable scenarios: single nut structure or occasions where the preload needs to be accurately adjusted. Steps: Add a shim between the nut end face and the mounting seat. Change the axial relative position of the nut and the screw by increasing or decreasing the thickness of the shim, and compress the ball and raceway. The preload needs to be tested repeatedly until the target value is reached. c. Spacer adjustment method Principle: add a spacer (sleeve) of a specific length between the double nuts, and control the preload by changing the length of the spacer. Advantages: High preload accuracy, suitable for equipment with high rigidity requirements (such as CNC machine tools). Steps: Measure the original spacing between the two nuts. Calculate the required spacer length based on the preload amount (usually the required compression amount = spacer length - original spacing). Install the spacer and lock the nut. d. Variable lead method (preload type ball screw) Principle: The manufacturer changes the lead of the ball circulation path to make the ball preload in the nut. Features: Users do not need to adjust, and can obtain standard preload by direct installation (need to select according to the load). 3. Key parameters for preload adjustment Preload level: usually divided into light preload (C0/C1), medium preload (C2/C3), heavy preload (C5), which needs to be selected according to the load and accuracy requirements. Preload amount calculation: Preload amount ≈ 0.05~0.1 times the elastic deformation corresponding to the rated dynamic load. Empirical formula: preload = (5%~10%) × lead (refer to the manufacturer's manual). Preload detection indicators: Axial rigidity: The displacement after applying external force must be less than the allowable value (such as 1μm/N). Reverse clearance: measured with a micrometer, the target value is usually ≤5μm. IV. Detection and verification after adjustment Torque test: Manually rotate the screw to feel whether the resistance is uniform and avoid local jamming. Use a torque meter to measure the driving torque and compare it with the manufacturer's recommended range (re-adjustment is required if it exceeds the limit). Reverse clearance detection: Fix the micrometer contact to the nut, move the screw in the forward and reverse directions, and record the displacement difference. Temperature monitoring: Run without load for 30 minutes to check whether the temperature rise is normal (generally ≤40℃). V. Precautions Avoid over-preloading: Excessive preloading will cause a sharp increase in friction heat, accelerated wear and even sintering. Lubrication management: After preload adjustment, it is necessary to add an appropriate amount of grease. It is recommended to use high-speed and high-load lubricants. Environmental adaptability: The preload amount needs to be re-checked in high or low temperature environments (affected by the thermal expansion coefficient of the material). Regular maintenance: Check the preload status every 300-500 hours of operation and readjust it if necessary. VI. Common problems and solutions Problem 1: Large running resistance after preload adjustment Cause: Excessive preload or insufficient lubrication. Solution: Reduce the thickness of the gasket or the length of the spacer sleeve and increase lubrication. Problem 2: The reverse clearance still exceeds the standard Cause: The nut is worn or the screw shaft is bent. Solution: Replace the nut, straighten the screw or replace a new screw. Problem 3: Abnormal noise and vibration Cause: Uneven preload or broken balls. Solution: Readjust the preload and check the ball circulation system. Through the above understanding of ball screw preload, if you want to learn more, please contact us, we are online 24 hours a day to serve you.