What Is a Linear Bushing?
A linear bushing, also known as a slide bush by some manufacturers, is a rolling bearing that facilitates linear motion on a shaft using the rolling motion of built-in balls.
This rolling motion, achieved with minimal friction due to the point contact between the balls and the shaft, allows for smooth movement of the bushing with little force.
Linear bushings, lacking propulsive force on their own, are often paired with mechanisms like cylinders, timing belts, and ball screws to facilitate movement in any direction along a shaft.
Uses of Linear Bushings
Linear bushings are commonly used in combination with linear shafts in sliding mechanisms for various applications such as precision equipment, industrial machinery, medical devices, and office automation equipment, particularly in settings where light loads and minimal vibration or shock are present.
As linear bushings themselves are not powered, they are frequently utilized with cylinders or motors to achieve linear motion.
They enable low-friction, high-precision linear motion between the bushing and the shaft, but careful consideration of shaft deflection and the operating environment is necessary when used under load.
Principles of Linear Bushings
Linear bushings are composed of an outer sleeve, a ball, and a cage. In conjunction with a linear shaft, they achieve linear motion through the rolling of the balls.
The outer casing, made of highly wear-resistant and tough bearing steel, undergoes heat treatment, and its inner and outer diameters are finely ground to facilitate high-precision positioning in linear motion.
The retainer features a guide groove for the ball, ensuring it rolls smoothly along the groove and the inner surface of the outer sleeve. This setup allows for accurate motion with minimal friction due to the point contact between the ball and the shaft.
Selection of linear bushings is based on factors like mounting orientation, travel speed, and usage frequency. Load calculations, rated life, and operating environment considerations are vital, especially when dealing with horizontal guidance under load, where shaft deflection can be an issue.