A novel approach to tribological measurements at harsh conditions

When dealing with high-tech equipment, accurate positioning is of the utmost importance to ensure durability and a productive lifetime. Unexpected high friction or wear of positioning mechanisms can lead to unnecessary down-time or products that are not up to specification. To ensure a sufficient lifetime, it is necessary to know beforehand how the sliding and rolling contacts will behave over time. This demand becomes more stringent when the machine operates at extreme conditions, e.g. vacuum or extremely low temperatures. Traditional greases and mineral oil based lubricants do not perform adequately in such extreme environments, as they either contaminate the vacuum or do not provide sufficient film thickness. TNO recently developed a unique measuring application, the TNO cryotribometer, in order to measure friction and wear of position mechanisms at harsh conditions. Preliminary results show that the contact pressure and the sliding velocity influenced the friction level greatly. This set-up is currently used to find and analyze different material combinations, which demonstrate a constant friction level under cryogenic vacuum conditions.