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The Praxis condition monitoring partnership between CNES and Schaeffler UK has enabled Corus engineers at a beam mill in Teesside to oversee an internal redesign to the hot saws gearbox.

In 2006, an FAG Dtect X1 online remote monitoring device was installed on the hot saws to determine their condition.

The hot saws consist of two circular saws, one fixed and one moving, which cut through H-section beams of hot steel as they exit the beam mill.

The online monitoring device soon highlighted problems that had previously gone unnoticed.

As well as imbalances to the saw blades, it also detected bearing and lubrication problems within the gearbox.

The Dtect X1 system has been monitoring this critical piece of machinery for more than two years and has provided the plant engineers at Corus with trending information on the condition of the gearbox.

It soon became apparent that there were inherent design faults within the gearbox itself that were causing regular bearing failures.

’We have been experiencing failures on our gearboxes for a number of years now,’ said Steve Bowman, the beam mill’s manufacturing engineer in charge of the hot saws and finishing equipment.

’By using the Dtect X1 system from Schaeffler, we’ve been able to pinpoint the exact source of these failures,’ he added.

With the help of Paul Harrison from the PCM team, Bowman was able to single out bearing C within the gearbox as the root cause of failure.

’The readings we were getting from the Dtect X1 device showed us that there was an issue with bearing C,’ said Bowman.

’The bearing was running hot right from the start, so we experimented with the bearing clearances and looked at the lubrication system.

’We noticed that bearing C was suffering from oil starvation, so oil was diverted from bearing D.

’By doing this, the running temperature of the bearing improved substantially,’ he added.

However, even though the bearings had been replaced and the lubrication system had been improved, the gearbox was still failing.

Following discussions with a transmission consultant, it soon became clear that this bearing was right at the edge of its design capabilities.

Because the gearbox was prone to continual bearing failure, Bowman challenged the consultant to come up with a new internal design that would eliminate bearing failure.

Using the data from Dtect X1, the existing gearbox has since been modified to include a new bearing arrangement and lubrication system.

By keeping the same gearbox casing, Corus is now able to easily interchange the existing two gearboxes and avoid the cost of a new one, which is around GBP110,000.

’What the Dtect X1 system allowed us to do was gain valuable experience and time,’ said Bowman.

’Not only did we know that there was a problem, but we also knew the degree of the problem.

’It gives us the confidence to run the gearbox until the next planned outage, knowing that we won’t have a catastrophic gearbox failure on our hands and that we will have everything in place to make a planned change if required,’ he added.

The Dtect X1 device has allowed Corus engineers to improve their plant preventative maintenance regime.

With the information they have gathered in recent months, they have also been able to work with the saw blade manufacturers to ensure that the blades are balanced to a much higher degree than previously supplied.

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