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Built-in sensors automate lubrication of linear axes

26 March, 2018

Schaeffler has developed a system that automates the lubrication of linear recirculating ball bearing and guideway assemblies using built-in lubrication and vibration sensors, thus eliminating the need for manual lubrication. The system, called DuraSense, provides individual linear axes with the precise level of lubrication they need, based on their loads and other factors. Up to six carriages can be monitored on one axis.

The system prevents both insufficient lubrication and over-greasing, extending machine lives and reducing failure rates. It can also detect relubrication system failures caused, for example, by leaking hoses or blocked lubricating nipples. It does not need complex monitoring using pressure sensors, such as those used in centralised lubricating systems. It will protect even heavily interconnected systems against costly downtime.

If a monorail guidance system moves only short distances and experiences low forces, the system reduces the frequency of lubricating impulses. If load conditions become more severe, it increases the frequency. If a carriage becomes contaminated by foreign bodies or fluids, the built-in vibration sensors detect this through solid-borne sound transmission and trigger a lubricating impulse, flushing out the contamination, along with the lubricant.

Schaeffler says that, without this function, the guidance system would continue to operate with contamination remaining in the rolling contact until the next planned lubrication. This could result in severe damage.

The DuraSense system can also help to determine the remaining useful life in linear recirculating ball and roller bearing and guideway assemblies. After these assemblies have been in operation for extended period, material fatigue can occur close to their surfaces. The measuring system detects this, and increases the frequency of the relubricating impulses. The axis therefore runs smoothly and product quality remains constant for longer.

Even though the linear guidance system continues to operate in this condition, the shorter intervals between the lubricating impulses can be sensed and used to predict the remaining useful life of the guidance system. This calculation, which will in future be available as a digital service, allows maintenance work to be scheduled based on actual operating data and the condition of the system.

Built-in lubrication and vibration sensors determine when the linear guides need lubrication and can determine their remaining useful life

As well as ending the need for manual lubrication, Schaeffler says that the DuraSense system means that machine-builders will no longer be dependent on the sometimes limited control options offered by centralised lubricating systems.

The system is available for Schaeffler’s KUVE and KUSE four- and six-row linear recirculating ball bearing and guideway assemblies and its RUE linear recirculating roller bearing and guideway assemblies. The sensors can be placed on either side of the carriage and to the left or right of the end-piece.

The automated lubrication function was first announced for Schaeffler’s linear recirculating roller bearing and guideway assemblies in 2017. The latest development extends it to ball bearing systems as well.

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