Proactive Predictive Maintenance Using IR Thermography

One of the best PdM techniques is IR thermography, which monitors the condition of machines, systems, and structures ensuring efficient operation

In a manufacturing environment, predictive maintenance (PdM) is crucial to daily operations and worker safety. One of the best PdM techniques is infrared thermography, which monitors the condition of machines, systems, and structures ensuring they are operating efficiently. Infrared (IR) thermography is not just limited to electrical equipment and can have a large impact on basically any rotating equipment, such as electric motors, gearboxes, and centrifuges.

IR thermography is a process which an object’s thermal energy is measured through the use of infrared cameras and other devices. Just as its use in manufacturing isn’t limited to electrical equipment, IR thermography isn’t only for equipment that produces heat. Because it measures energy and not temperature, IR thermography detects energy in cold objects as well. It accurately exposes if machinery is operating within normal a temperature range, which prevents costly repairs and downtime when used as a method of predictive maintenance.

The basic concept behind IR thermography is that objects with a higher than absolute zero temperature emit energy and therefore can be measured. There are three types of thermal energy emitted from an object:

1. Energy reflected from the object
2. Energy transmitted by the object
3. Energy emitted from the object

In a PdM program, only the latter is important, and must be singled out amongst the other two types of energy in order to get accurate data.

This is where the need for special instrumentation is important. Most infrared monitoring devices use special filters to eliminate unnecessary data. A point of use IR thermometer can be a valuable tool in PdM applications because it can be used in conjunction with vibration data to monitor the temperatures of motor windings, piping, and bearing caps.

By including IR thermography into a PdM schedule, manufactures can effectively monitor all critical processing systems that rely on heat transfer. It can be used to detect potential problems before they become larger issues, and aids in worker safety.

IR Thermography should be a regular inclusion in a PdM program, as the benefits are related to how often it’s used. Plant thermographers should conduct a regular IR survey to avoid equipment breakdowns and manufacturing crises. Consistent monitoring with infrared surveys is the only way to use thermography as a predictive form of maintenance. Otherwise, by using the technology only when something is wrong, the plant is reverting to reactionary maintenance, which causes downtime in production, and may lead to the need to use backup feeds.

Aside from granting a safer working environment, IR thermography can help protect a company’s costs. When used as part of an energy audit, infrared thermography can detect excess energy loss, which can affect the bottom line of production. Because potential issues can be detected in the early stages, thermography helps sustain the life of the manufacturing equipment, and ensure quality performance and efficiency. To get the most out of infrared thermography as part of a predictive maintenance program, it is critical that a trained thermographer assess the operating equipment regularly.

Fluke provides a real-world example of the effectiveness of PdM using an IR scan at a sawmill. Being able to view machinery in a non-invasive way provides an easy way to become proactive with your PdM program.

If you can use a digital camera, you can learn to operate the Fluke Ti30 thermal imager. While the images from the Ti30 may not make it into the family photo album, they could very well save your business thousands of dollars when integrated into your overall preventive maintenance strategy. Just ask Dave Feniak at the Drayton Valley, Alberta, location of Weyerhaeuser Co., one of the world’s largest integrated forest products companies.

Feniak, the sawmill’s electrical maintenance supervisor, purchased the imager and, after some basic training on its use, went into the plant and found a problem. A big problem.
“We have been doing IR (infrared) scans routinely on a six- to nine-month basis since 1992 or so, and we usually find very few problems. I was looking at bearings in the planer mill and noticed a very hot spot in the far distance,” Feniak recounts.

The Ti30 has a built in laser pointer, and once Feniak turned it on he found that heat was being generated about 150 feet away from the sawmill trim-saw motor.

“Taking the camera over to the motor we saw the motor windings were at 90 °C (194 °F),” he says. “We did amp checks and found a severe imbalance between phases. This was on a Thursday, so we got our spare motor out and installed it the next morning on the maintenance shift, with no downtime. If the motor had failed on shift the cost would have been approximately $30,000 for the downtime, plus the repairs would have been more expensive.”

Weyerhaeuser’s $14,000 investment quickly paid for itself. And it has certainly helped to legitimize the concept of preventive maintenance at the sawmill.

Having the ability to see problems in early stages is certainly advantageous over the “run-until-failure” ideology. Weyehaeuser now has the ability to plan, schedule, and make repairs before equipment fails, avoiding major breakdowns and costly downtime.

Studies show that a planned repair job typically takes only half as much time as an unplanned job. In his book, Plant Engineer’s Handbook, Keith Mobley links the following benefits to preventive maintenance:

Maintenance costs — down by 50 %Unexpected failures — reduced by 55 %Repair and overhaul time — down by 60 %Spare parts inventory — reduced by 30 %30 % increase in machinery mean time between failures (MTBF)30 % increase in uptime

And for the typical manufacturing plant, a 10 % reduction in maintenance costs has the same bottom line impact as a 40% increase in sales.

Using IR thermography also provides an effective way to prove repairs have been properly made to insurance adjustors.

According to Fluke Electronics Canada sales representative Ken Reeves, the unit’s software helps users take area measurements and then print a report with images and annotations to use as supporting documentation. That can be particularly useful in dealing with insurance underwriters, Reeves adds.

“It helps to have the thermography study in your preventive maintenance report so the insurance underwriter has proof that a problem was fixed and that the plant will stay up and running. If your report shows you made the necessary repairs, the insurance company will have no problem covering downtime expenses,” Reeves says.

Necessity is the mother of invention and in cases such as this, it most definitely true. The rough economic times our economy has been trudging through has placed facility managers in a tight spot: trying to predict equipment failure in the most proactive, economical, and efficient manner.