https://www.vxolinearmotion.com/products/bearing/
A linear motion bearing custom is a machine element that constrains relative motion to only the desired motion and reduces friction between moving parts. In VXO, one of the top ball screw and linear bearing exporter in China, the linear motion bearing design may, for example, provide for free linear movement of the moving part or for free rotation around a fixed axis; or, it may prevent a motion by controlling the vectors of normal forces that bear on the moving parts. They are typically made from materials such as steel, aluminum, or plastic, and can be designed to handle a wide range of loads and speeds. Some common applications for linear motion bearings include robotics, CNC machines, and linear actuators.Most linear guide bearing quality facilitate the desired motion by minimizing friction. Bearings are classified broadly according to the type of operation, the motions allowed, such as precision angular contact bearings and cam roller bearings, or to the directions of the loads (forces) applied to the parts.