Forecasting failure

Drives, motors, pumps and other pieces of essential plant equipment are far too easily forgotten until something goes wrong.

But the cost of unexpected plant downtime has begun to bite too deeply for some process sectors, giving rise to a host of technologies tasked with predicting the development of faults in equipment before they actually occur.

Food and drink suppliers are one of the process sectors leading the charge in adopting predictive maintenance strategies says Richard Chamberlain, sector service manager Bosch Rexroth UK.

Many food and packaging companies have already invested in preventative maintenance

Richard Chamberlain

Because they are churning out thousands of products around the clock, they can ill afford to take a reactive stance, he says.

From a preventative maintenance perspective, their key focus is on monitoring the drives and controls used in their process.

“Many food and packaging companies have already invested in preventative maintenance,” says Chamberlain. “The cost of this is not really a big issue because if a machine goes down, it can cost them thousands of pounds.

“They are good at what they do, and very efficient when it comes to planning maintenance, and knowing when it is time to look at machines to prevent down time,” he adds.

“We’ll go in on a quarterly basis and run health checks, monitor their equipment, and make sure their maintenance staff are trained up and carrying the correct spare parts.”

But not all sectors have embraced such a proactive approach. Although remote monitoring can play an important part in safely running the hydraulic and electronic drive systems found in cranes and large cylinders used in offshore industries, adoption is still in its early days.

“I think they understand the need for preventative maintenance,” says Chamberlain, but the issue is that those managing maintenance offshore sometimes don’t factor in the ‘below deck’ equipment.

A reactive approach to maintenance and servicing not only leaves a company at the mercy of production downtime: safety and reputation can also be adversely affected, says Chamberlain.

While some perceive preventative maintenance as too expensive, letting equipment run to the point of failure can prove even more costly, he adds.

“We are developing a tool that can calculate the downtime and repair cost verses the planned maintenance investment.”

Another predictive technology growing in popularity is thermal imaging. This can provide a useful snapshot of the health of a system, says Andy Baker, UK & Ireland sales manager at FLIR Systems.

A key factor in the rise of thermal imaging technology is the steady fall in the cost of cameras owing to the widespread use of thermography across industry at large, he says.

“Historically the technology was the preserve of larger companies with big budgets but now it is eminently affordable for use in any engineering discipline,” says Baker.

By comparing both visual and thermal modes, it can be easier to determine what’s going on in the image.

“It makes the image details crisp and clear, allowing details such as the writing on a fuse board, to be seen clearly on the thermal image,” he says.

This means that a camera used for checking an electrical circuit can also be applied to under-floor pipework, spotting an overheating bearing or detecting missing wall insulation.

Another benefit, says Baker, is that it puts the problem into context, showing the hotspot along with its relationship with other components, which can assist in diagnosing the nature of the fault.

It is also a good companion to more traditional sensor systems sending measurement data to a central management system, says Baker.

“It allows the maintenance teams to gather more information on the problem that has been flagged up by continuous monitoring,” he says.

He says FLIR’s thermal imaging cameras can also ‘talk’ to ancillary equipment such as clamp meters and ammeters, embedding their data in the appropriate thermal image, which brings much more intelligence to the analysis process.

Vibration is also emerging as an important parameter to measure for equipment with moving parts, says Andy Anthony, managing director of industrial sensor supplier, Monitran.

The company supplies a range of condition monitoring solutions, including velocity sensors, that measure vibration on a machine to confirm it is working within tolerance.

“We are finding that vibration-based condition monitoring is becoming a major tool in the armoury,” he says.

“In rotating machinery it gives a sensible level of information that is not swamping users with too many facts and figures.”

However, those that do want to dig deeper can opt for detailed analysis of a larger quantity of data, he says.

For example, a gearbox with 50 teeth will have a particular vibration signature, but if one of those teeth was broken, you could detect a different signature every 50th cycle.

“Because you know what is failing, that intelligence can then be fed back into stock control,” says Anthony.

Although some industries such as paper, steel and water have been monitoring vibration in machinery with moving parts for many years, Anthony says he has observed a recent rise in interest from other sectors such as food and drink.

“It is in the conveyance side of the process where we are seeing increase in demand as they realise these are critical elements of the plant,” he says.

“Sensors of velocity or acceleration are extremely sensitive to a change in condition and are a long way ahead of other methods.”

Regardless of which methods a company chooses, managing the flow of incoming data is essential, says Gil Acosta, director of engineering services at eMaint Enterprises.

“Companies are recognising that no single solution can perform every task,” says Acosta.

“So, they are selecting ‘best of breed’ solutions and sharing data between those systems.” The ‘condition monitoring’ feature in eMaint’s X3 computerised maintenance management system (CMMS) was created with this in mind, allowing predictive maintenance to be incorporated into other activities.

“Our ability to accept data from monitoring equipment and use it to fuel our ‘maintenance management’ engine that triggers work and keeps track of associated costs and work history is an example of this,” he says.

“You can define a number of different monitoring classes such as vibration or temperature, which allow you to incorporate different predictive technologies into your programme,” says Acosta.

This condition monitoring feature can be configured to meet the specific requirements of each organisation, he says, allowing staff to define which equipment will be monitored, how often the meter readings will be imported and when a corrective action will be triggered.

“This allows companies to migrate from a recurring planned preventive program to one that is based upon indicators that equipment is not operating as intended.”