Paul Boughton
Lubricants in bearings and gearboxes help to minimise the energy lost through friction, yet a percentage of the input energy is still required to compensate for friction losses. However, researchers at the Fraunhofer Institute believe that lubricants made of liquid crystals could reduce friction to almost zero.
When you think about the number of bearings and gearboxes in use just in conveyors, walkways and other equipment in airports around the world, the total energy lost to friction in bearings and gearboxes is in the range of several gigawatt-hours per annum. A substantial amount of this is lost through friction. In wind turbines and in cars, too, a percentage of the energy is spent on friction. Novel lubricants that almost eliminate the effect of friction could be the answer. Once they have been set in motion, the bearings run and run.
Andreas Kailer, head of department at the Fraunhofer Institute for Mechanics of Materials (IWM) in Freiburg, Germany, explains what makes the new lubricant different from the oils that are currently used to lubricate bearings: "This lubricant is made from liquid crystals like the ones we know from flat-screen monitors. In contrast to normal liquids, the molecules in liquid crystals have a certain orientation – you might compare them to matches with their heads all pointing in the same direction."
In a joint project with the Fraunhofer Institute for Applied Polymer Research IAP in Potsdam and the Mainz-based company Nematel, the IWM researchers are investigating which liquid crystals are most suitable for use as lubricants, and under what conditions. Their testing unit exerts a certain amount of force on a clamped metal cylinder that is moved back and forth over a supporting contact surface.
While the friction hardly changes when using conventional oil, it drops to almost zero after a while when liquid crystals are used. The time that this takes depends primarily on the pressure with which the moving cylinder is pressed against the contact surface. If you were to compare it to a toboggan, it would correspond to the weight of the child sitting on it. Kailer says: "Liquid crystals have not been suitable as a lubricant for ball bearings until now, as the contact pressure is too high – the friction does not drop far enough. For slide bearings, on the other hand, liquid crystals are the perfect solution."
Since liquid crystals have been produced mainly for monitors up to now, they have to be ultra-pure – which makes them very expensive. So the researchers now plan to simplify the synthesis process, since less pure substances are also suitable as lubricants. Kailer concludes: "We hope to be able to market a liquid crystal lubricant in three to five years' time."
For more information, visit www.fraunhofer.de
When you think about the number of bearings and gearboxes in use just in conveyors, walkways and other equipment in airports around the world, the total energy lost to friction in bearings and gearboxes is in the range of several gigawatt-hours per annum. A substantial amount of this is lost through friction. In wind turbines and in cars, too, a percentage of the energy is spent on friction. Novel lubricants that almost eliminate the effect of friction could be the answer. Once they have been set in motion, the bearings run and run.
Andreas Kailer, head of department at the Fraunhofer Institute for Mechanics of Materials (IWM) in Freiburg, Germany, explains what makes the new lubricant different from the oils that are currently used to lubricate bearings: "This lubricant is made from liquid crystals like the ones we know from flat-screen monitors. In contrast to normal liquids, the molecules in liquid crystals have a certain orientation – you might compare them to matches with their heads all pointing in the same direction."
In a joint project with the Fraunhofer Institute for Applied Polymer Research IAP in Potsdam and the Mainz-based company Nematel, the IWM researchers are investigating which liquid crystals are most suitable for use as lubricants, and under what conditions. Their testing unit exerts a certain amount of force on a clamped metal cylinder that is moved back and forth over a supporting contact surface.
While the friction hardly changes when using conventional oil, it drops to almost zero after a while when liquid crystals are used. The time that this takes depends primarily on the pressure with which the moving cylinder is pressed against the contact surface. If you were to compare it to a toboggan, it would correspond to the weight of the child sitting on it. Kailer says: "Liquid crystals have not been suitable as a lubricant for ball bearings until now, as the contact pressure is too high – the friction does not drop far enough. For slide bearings, on the other hand, liquid crystals are the perfect solution."
Since liquid crystals have been produced mainly for monitors up to now, they have to be ultra-pure – which makes them very expensive. So the researchers now plan to simplify the synthesis process, since less pure substances are also suitable as lubricants. Kailer concludes: "We hope to be able to market a liquid crystal lubricant in three to five years' time."
For more information, visit www.fraunhofer.de
