Typically stationary, linear rails have grooves ground into their sides that run along the entire length of the rail, in which the linear bearing roller element, whether it by cylindrical or spherical, can move within. Since the linear bearings are limited by the grooves, linear rails are able to control the direction that the linear bearings move in.
As an integral part of a linear slide, linear rails are utilized in a wide range of industries including: medical and pharmaceutical, for use in drug dispensing applications as well as positioners in hospital furniture such as beds and chairs; food and beverage, for processing and packaging applications; industrial manufacturing, for use in automated machinery such as drilling and grinding machines as well as other factory and process automation applications; and automotive, for use in components such as engine compartments.
Linear rails are also used in many other diverse industries, such as semiconductor, chemical processing, optical, textile and commercial, for application ranging from office machinery to CNC machining centers.
Linear rails have a very simple design: solid, flat metal body with two grooved sides that extend from the flat base in 90º angles. The size of the grooves, also known as raceways, affects the load-carrying capacity of the linear slide. A linear rail is one of the main components of a linear slide, the other being a moving carriage.
The moving carriage has mobility due to either ball bearings or roller bearings; although, ball bearings are more common. Inside the moving carriage there is typically a type of screw assembly, either with a ball screw or lead screw, and a nut.
The nut provides the linear movement since it is threaded onto the non-rotating part of the screw, then driven along the threads of the screw in the corresponding direction to the screw’s rotational movement.
Linear rails can be either manual or motorized. Motorized linear rails have a more complex design, and both types can be hardened or ground for increased tensile strength.
Some common types of motorized linear rails include belt drive rails and chain drive rails. Linear belt drive rails have the addition of a belt made from various elastomers, allowing for quiet, yet rapid linear motion. Often used as alternatives to belt drive rails, linear chain drive rails are better suited for high temperature environments and are mainly employed in lifting applications.