There are many applications within metrology – such as coordinate measuring machines (CMMs) – that require high precision positioning.
This can be reliably achieved using motion stages, and bearings are a vital component of any motion stage set-up. There are many different variations of mechanical bearing available – including ball and roller models – but the more recent development of air bearings offers a number of advantages over mechanical options for these applications, enabling vibration-free motion and accurate velocity control.
Precision and reliability
Motions stages are used across various applications that require precision positioning, including a wide range of metrology tools to measure the roundness, flatness, surface profiles and thickness of shafts, turbine blades, semiconductor wafers and other critical components. There are many types of motion stages, offering a range motion profiles that vary in complexity, from a simple line to intricate three-dimensional patterns. However, the accuracy and smoothness of movements is always affected by the types of bearings used in the set-up, as vibrations or jitter can compromise the precision of positioning. Luckily, there is an efficient way to minimise these disturbances; air bearing-based stages replace direct contact with a thin film of air, which helps to avoid wear, friction, vibration and hysteresis effects. This makes it possible to satisfy performance criteria such as superior angular repeatability, geometric precision and minimal motion errors, as well as straightness and flatness for linear bearings, and axial and radial runout for rotary bearings. For example, PI rotary air bearings can ensure that the axial motion error is below +/-25 nanometres, which allows measurement systems to detect roundness errors well under 0.1µm.
Tailored motion systems
PI has been designing and manufacturing high quality bearings to support metrology applications – including CMMs – for many years, making it possible to create world-class metrology equipment with sub-micron precision. The company works with leading manufacturers around the world, and even offers custom-made air bearing motion systems for instances where the standard product range does not satisfy application requirements, such as for measuring complex geometries with extreme precision. Even though PI does not offer complete CMMs, the company can design and build a custom multi-axis air bearing motion system, supplied with all necessary parts for reliable installation and operation. This includes a granite structure, together with drive and feedback technology, cabling, controller, and a machine base with vibration isolation. These systems often combine linear and rotary motion, with up to eight synchronized axes of motion.
Get in touch
If you are in need of a highly precise motion control system, do not hesitate to get in touch with us. We can help you find the optimal positioning solution for your application.
