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Fibre optics give products a longer lifespan and increased safety

Rolling bearings with built-in fibre optics that measure loads and temperature in the warehouse have been used in pilot tests for a few years and are approaching commercialisation. Together with technology partners Proximion and RISE, SKF is Now developing a new, complementary technology that measures vibrations throughout the optical fibre. A smart industry gives the user better control of processes and quality.

Carolina Fransiscangelis
Photo: RISE
Carolina Fransiscangelis

With the smart rolling bearings (collective name for ball bearings and roller bearings) that have been developed and are approaching market introduction, users can obtain information about the condition of the bearing by precise measurements of temperature, strain and load at a number of selected sensor points in the optical fibre. The technology is known as FBG (Fibre Bragg Gratings). Simplistically, it reflects a specific wavelength of light at the measurement points when changes in for example temperature occur.

The Information can be used for process control and also provide the ability to change bearings in time, thus avoiding unnecessary production stoppages.

The new so-called SenseMachine technology, which SKF, Proximion and RISE has been working on developing since the summer of 2017, means that bearings can also act as instruments for more overall process and quality control. The technology combines FBG with vibration measurement along the entire optical fibre.

"It allows us to monitor changes along the entire fibre. There is no need to pre-select points where the measurements will be made", says Lars Kahlman, who is the SKF technical specifier in the project.

A major advantage of the fibre-optic sensing systems is that they can be retro-fitted in existing production environments with only minor modifications. Most of the sensor technologies available today require the rebuilding of factories (due to problems with handling electronic components) in order for them to be able to be fitted.

Proximion, part of the Hexatronic Group, are experts in fibre optic measurement and data collection in tough industrial environments. Therefore an important task for Proximion in the project is to develop faster FBG systems.

RISE's role in the project, which tested a first prototype in the summer of 2018, is primarily to be responsible for producing and testing the prototype with the two combined technologies.

The work has led to increased accuracy in measurements and greater sensitivity at high frequencies. The sensitivity means that the bearing detects vibrations throughout the entire machine it is located in. This can be used for the early detection of more types of production and process problems. And of course, for changing the bearing in time if required.

"By tracking how the bearing behaves, a damaged or worn bearing can be replaced before it causes a major problem such as a fire. In addition to the technology providing a safer production, it can also extend the machine's lifespan", says Carolina Franciscangelis, project manager at RISE.

SKF demonstrated its first smart roller bearing with built-in fibre optics for measuring in 2012.

"We work continuously with the development of systems for the fibre optic monitoring of machines. In this respect, this type of rolling bearing will be a complement that will give us a broader product portfolio", says Lars Kahlman.

How long will take from the planned tests in the autumn to a finished product on the market is hard to say, but Lars Kahlman estimates that it may be about two years.

This Summer a second prototype will be ready for testing. It will have better performance, contain smaller components and be more compact than the first. Thus a major step towards a product ready for active use will be taken.

The collaboration will continue until the summer, but may be extended until the autumn.

"It has been very rewarding, both in terms of technology development and to establish new contacts. It has given us at SKF a broader development base", says Lars Kahlman.