Positioning stages, or positioning tables, are linear slides with the addition of a drive mechanism that allows them to be used to provide both low-friction linear movement and controlled, precision positioning along a linear axis. Also referred to as linear stages, positioning stages can be designed in center-drive or side-drive configurations as well as to provide movement along multiple axes.
Able to be used in a wide range of applications, positioning stages are utilized in such industries as: industrial manufacturing, in applications including automation equipment, CNC machining equipment and robotic assembly machinery; marine, automotive and aerospace, for use in construction and navigation applications; medical and biotechnology, for extremely fine resolution positioning; and construction and architectural, for material handling and automated measurement. Additional industries served by positioning stages include semiconductor, photonics, pharmaceutical and electronics for applications such as automated liquid handling and spectrophotometric measurement. Some of the many benefits of using positioning stages for these diverse applications include speed, accuracy and reliability as well as repeatable precision performance. Choosing the best positioning stage for the application does not only depend on performance, since plant conditions are also an important consideration.
A positioning stage consists of a platform that moves in relation to a stationary base and is connected to the base by way of a moving carriage. The mobile carriage is joined to the base's raceways, which are grooves on either side of the base, by linear bearings. These linear bearings may be roller or ball bearings. Both types of linear bearings are used to reduce the amount of friction between objects and allow for heavy objects to be more easily moved. Of the two, ball bearings are the most common and are typically made out of either steel alloys or ceramics. Instead of being spherically-shaped like the aptly named "ball" bearings, roller bearings are cylindrically-shaped. No matter the type, the linear bearings allow for the motion to occur and the raceways serve as guides to restrict the motion of the platform to one dimension. The position of the moving platform to the fixed base is typically controlled by drive mechanisms that can be manual or motorized and include: handwheels, which can include any type of wheel worked by hand; stepper motors, which are brushless, synchronous electric motors; or linear motors, which are alternating current (AC) electric motors. Although many metals may be used, the most common metals used to construct positioning stages include stainless steel, aluminum and steel alloys.
