When ordering ball screw kits, the magnitude of the preload force required can be informed to the manufacturer based on the force-bearing conditions of the ball screw, so that the manufacturer can preload according to the given preload force. If the preload force is appropriately selected, the ball screw can operate in an optimal working state. Specifically, when the preload force increases, the contact stiffness between the steel balls and the raceways increases, and the transmission accuracy also improves. However, a considerable preload force will increase contact stress between the steel balls and the raceways, thereby reducing the service life and transmission efficiency.
The magnitude of the preload force for the ball screw assemblies should ideally ensure that no axial clearance occurs in the screw-nut pair when the ball screw pair is subjected to the maximum axial working load. It is required that the value of the preload force should be greater than one-third of the maximum axial working load. Additionally, since applying preload to a double-nut mechanism will cause additional frictional torque, issues of efficiency and service life must also be considered.
