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The scientists in the project, are focusing on to develope Tribological Condition Monitoring (TriCoMo), ie monitoring of the lubrication and the operation conditions of the bearing. The sensor is mounted in the bright steel box with SKF marking. The light blue bearing housing is about 40 cm in diameter. Photo: Luleå tekniska universitet View original picture , opens in new tab/window

Warning system for water in grease at paper mill

Published: 10 March 2017

Researchers at Luleå University of Technology, in cooperation with SKF and BillerudKorsnäs in Karlsborg, are developing a novel sensor that is expected to save millions by reducing downtime in pulp and paper mills and steel mills. The secret, a sensor that warns for water contamination in grease lubricated bearings, thereby preventing serious damage to the machines.

– At present condition monitoring through vibration monitoring is common in the industry. This tells you you when a machine starts to break down, for example due to water or other contaminants in the bearings. Our sensor warns even before the machines are damaged and can thus, for example, a paper mill save millions on preventing downtime, says Pär Marklund, assistant Professor in Machine Elements at Luleå University of Technology.

Over 200 rollers

Photo: Lennart Salander
BillrudKorsnäs in Karlsborg manufactures sack and kraft paper for different types of industries and applications. Photo: Lennart Salander

Industries like pulp and paper mills and steel mills are extremely vulnerable to moisture. Since grease is used extensively as a lubricant in the paper machine’s bearings, water contamination is very difficult to detect.

In paper mills, the entire environment is moist due to the manufacturing process, which dries the paper pulp to manufacture paper. After the pulp is sprayed out on a porous plastic mat where water is sucked out, the paper web goes between large rotating heated rollers, where the paper is further dried. The rollers in the paper machine can rotate thanks to large roller bearings that are oil or grease lubricated. The paper machine has over 200 rollers and thus a large number of bearings has a risk of becoming contaminated with water.

If water gets into the grease in a bearing and remains for a long time, it influence the grease characteristics and the bearings start to rust. At worst, it leads to unplanned stops when the bearings must be replaced. In a paper factory like BillerudKorsnäs Karlsborg, where the fabric goes around the clock a stops soon costs several millions in lost production. BillerudKorsnäs Karlsborg has an annual production of 300,000 tons of craft paper, sack paper (white) and pulp.

Monitoring of the lubrication of the bearing.

– Although today's surveillance systems,  often based on vibration analysis, is very refined and sensitive, one can nevertheless only get a warning when bearings already have developed a small fault. We are now focusing on to develope what we call TriCoMo or Tribological Condition Monitoring, ie monitoring of the lubrication and the operation conditions of the bearing. If you can discover, for example, when water has contaminated the grease, there is often an opportunity to improve lubrication before it leads to irreversible damage to the bearings, says Pär Marklund.

Because researchers at Luleå University of Technology, can work with the new sensor both in the lab and in the industrial environments, the researchers hope to develop the sensor so that it has a sufficient accuracy while being robust enough to withstand harsh industrial environments.

Aiming for wireless communication

– We are now also aiming to develop the sensor in combination with other projects at the university to get wireless communications, and to be able to use the energy from the bearing itself to power the sensor, says Pär Marklund.

The research has been made in the strong research area Smart machines and materials at the SKF-LTU University Technology Centre (one of only five similar centers in the world). SKF-LTU University Technology Center in advanced condition monitoring is working to develop tomorrow's technology for monitoring of machines with smart bearings with integrated sensor technology, wireless communication and so-called energy harvesting technology.

Pär Marklund

Pär Marklund, Professor

Phone: +46 (0)920 492415
Organisation: Machine Elements, Machine Elements, Department of Engineering Sciences and Mathematics