Superconductors have fascinating properties: when cooled to a certain temperature, they not only lose their electrical resistance but can also “freeze” the field of a permanent magnet positioned nearby and thus hold the magnet in position at a constant distance. The resulting stable air gap allows the contact-free, frictionless positioning and moving of objects without the need for control technology. For several years, Festo has been carrying out research into the advantages of superconductor technology for automation; the company is demonstrating three new, unique application concepts at the 2014 Hanover Fair.
The first research platforms at the 2013 Hanover Fair already illustrated how objects can be maintained in a state of levitation and be moved without contact, for example. Festo has now further developed these ideas with SupraHandling 2.0, SupraShuttle and SupraChanger – its three current exhibits based on SupraMotion 2.0. These exhibits demonstrate the linear and rotary motion of levitating objects in all directions and in all spatial positions. All three of these new applications make use of electric cooling units with cryostats (refrigerated containers). The exhibits make use of decentralised control and do not require regulation technology to maintain objects in a state of levitation. They demonstrate opportunities for specific applications of this technology in automation, with a comprehensive solution package from control technology to temperature monitoring.
Superconductors: materials with special properties
Superconductors are metals, metal compounds or ceramic materials that acquire very special properties when cooled below a so-called critical temperature: not only does their electrical resistance then drop abruptly to zero; the superconductor also stores the field of a permanent magnet at a predetermined distance. If the superconductor is cooled down to its critical temperature and the spacing element is removed, the magnet will remain hovering in a stable condition above the superconductor and will return exactly to this stored position after being removed or displaced. For the high-temperature ceramic superconductors used by Festo, the critical temperature is about 93 kelvin (–180 degrees Celsius).
SupraHandling 2.0: linear motion in three spatial layers
With SupraHandling 2.0, a levitating carriage moves over two magnetic rails 2.5 metres in length. This carriage is fitted with three cryostats with superconductors. The entire system can be rotated by up to 180 degrees about its longitudinal axis, thus enabling the carriage to travel vertically or even upside-down. SupraHandling 2.0 thus demonstrates stable non-contact positioning, which for example could enable the levitated transportation of objects in production.
SupraShuttle: hovering and moving in any direction
With the SupraShuttle, Festo is demonstrating the movement of a levitating object in all directions and, for the first time, the handling of the superconductor element itself: the cryostat with the superconducting material is transferred from one electric axis system to another. The exhibit also shows how easily hovering objects can be introduced into a hermetically sealed space and moved within it. This feature would be useful, for example, for applications involving work with gases or in a vacuum.
SupraChanger: controlled rotation
With SupraChanger, an application for the first time transmits a rotational movement without contact and in a controlled manner to a magnet, which levitates due to superconductivity. The exhibit shows this effect in three automatically changing, distinct applications: a centrifuge, a blender and a hovering rotary indexing table. A possible future field of application would be laboratory automation, in which several processing steps are often performed on an object in sequence.
Electric cooling of the superconductors
All superconductors for the new SupraMotion exhibits are cooled by long-life electric compressors. The cryostats maintain the superconducting material at a constant temperature of around 93 kelvin (–180 degrees Celsius), with an energy consumption rate of about 12 watts per cryostat. SupraHandling 2.0, SupraShuttle and SupraChanger can thus be operated energy-efficiently and independently of cooling media such as liquid nitrogen.
A wide range of possible applications
A conceivable application in automation technology of the future would be the energy-efficient, stable positioning of objects, without the requirement for measuring or control technology. Superconductors would also enable objects to be moved beyond walls in confined spaces and in all positions. In view of this non-contact handling, there is also great application potential wherever equipment is required to be cleaned conveniently or during operation, for example in laboratory automation, medical technology or the food industry.