The concept and design of ball screws can be traced back to the late 19th and early 20th centuries. During the industrial revolution, with the development of the machinery industry, people's demand for linear motion became more and more urgent. Previously, a combination of a screw and nut was commonly used to achieve linear motion, but friction and imprecise properties limited the accuracy and efficiency of the system. In this context, the ball screw was proposed and developed. Ball screws utilize the rolling relationship between the balls and the screw, resulting in low friction and precise linear motion. In the design of the ball screw, the balls are arranged on the threaded track of the screw. When the screw rotates, the balls roll on the track, converting the rotary motion into linear motion. The introduction of the ball screw has greatly improved the performance of the linear transmission system, increasing the efficiency, stiffness and precision of the transmission. They are widely used in various fields, such as machine tools, robots, automated production equipment, stage lighting systems, printing machinery, etc., providing these systems with high precision, high speed and reliable linear motion. With the continuous advancement of science and technology and manufacturing technology, the design and manufacture of ball screw are also continuously improved and optimized. Modern ball screws have achieved higher load capacity, longer service life, higher stiffness and better reliability. They have become essential key elements in many mechanical systems, providing important support for industrial automation and production.

The miniature ball screw is a transmission device with high precision and high stability, which has the following characteristics: 1.High precision: The miniature ball screw adopts the form of contact between the ball and the thread, so that its axial clearance is small, the transmission precision is high, and it can realize high-precision positioning and translational movement. 2.High stability: The balls of the miniature ball screw are in contact with the thread, and the friction coefficient is small, which can realize smooth movement, thereby reducing mechanical vibration and noise. 3.Long life: The friction surface of the miniature ball screw is made of high-strength material, which can withstand high stress and high load, and its few moving parts and low wear rate, so it has a long service life. 4.High transmission efficiency: The miniature ball screw has high transmission efficiency and can realize high-precision movement under high-speed and high-load conditions. 5.Easy maintenance and replacement: The micro ball screw has a perfect lubrication system, which can ensure its stable operation for a long time, and it is also easy to maintain and replace if there is a problem.

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.