Do-it-yourself thermography

In-house thermography surveys save money and prevent unexpected production shutdowns.

Fluke's Ti20 thermal imager makes in-house thermography surveys affordable.

Instead of running mechanical and electrical systems until failure occurs, many manufacturing facilities incorporate infrared (IR) thermography surveys as part of their preventative-maintenance programs. Such surveys identify impending problems before they balloon into production shutdowns (see "Hot Shots," Nov., 2005, American Machinist, p. 46). And while shops typically use outside consulting firms for regularly scheduled thermographic surveys, simple, low-cost portable thermographic imaging cameras also are available to allow shops to conduct their own surveys.

Shops doing in-house thermographic surveys not only avoid unplanned downtime, they can eliminate the costs of hiring outside consultants and having to call those consultants back to verify that problems were corrected after a survey. In addition, those facilities that are not using thermographic surveys can implement the practice at a much more affordable cost than they could have in the past.

According to Jonathan Blaisdell, thermography product manager at Fluke Corp. (www.fluke.com), thermal imagers used to cost up around $30,000, but today, shops can purchase one, such as Fluke's Ti20 model, for well under $10,000, and the price includes the training necessary to use the equipment. Ti20 packages include portable, non-contact fully radiometric cameras that record temperatures from 14 to 662 degrees F, the company's InsideIR professional analysis and reporting software that has full, infrared predictive maintenance routing support, training materials and accessories.

Blaisdell says that many facilities that use outside consulting firms supplement the service with their own in-house thermography surveys to eliminate extra costs. For instance, if an outside thermography survey finds potential problems such as loose connections or worn motor bearings, usually the customer gets a report and has to make the necessary repairs. To ensure that repairs actually are corrected, a follow-up survey typically is required, and that is an addition to regularly scheduled surveys. Shops that have their own thermal imagers can avoid the cost of such an extra visit and confirm the success of repairs on their own.

While the latest thermal imagers are simple to operate, Blaisdell warns that users must have an understanding of the technology and theory behind infrared surveys and that, in some instances, having a consultant firm do surveys may be the better way to go. For successful in-house programs, training is the most important element, he says.

Whoever does the imaging needs to know, for instance, the difference between a good emitter and a bad emitter and how reflectivity comes into play. Good emitters, such as components with black bodies, freely transmit heat energy from their surfaces, while bad emitters, such as components with polished aluminum bodies, tend to reflect the thermographic imager's infrared beam.

Bad emitters can bounce infrared beams back toward the thermographic imager, causing it to capture the heat image of the maintenance technician holding the camera instead of the piece of equipment that the technician is trying to test. However, this phenomenon can work to a shop's advantage when shooting a hard-to-reach component. Shop's can use a reflective piece of material adjusted so that the beam bounces off of it and to the intended test subject.

Reflectivity occurs when a component's hot reflection appears on another component, making that component seem hot when in reality it is not. This occurrence is the inverse of what happens when shooting a bad emitter, and technicians have to adjust their position or the camera's position to correct for that reflectivity, explains Blaisdell.

Besides understanding infrared reflectivity, shops that conduct in-house thermographic surveys must familiarize themselves with the different equipment they are planning to test. Electric motors, for instance, should be running under normal operating conditions, and technicians must be aware of their normal internal-operating temperatures. Technicians also must be aware that other components should not be as hot as motor housings.

Bearings also should be at operating temperatures — steady-state conditions — and running under normal load when they are tested thermographically. Technicians then can capture an image of the bearing to be checked and, if possible, an image of bearings in the same area performing similar functions. This provides a picture of what a normal operating bearing's heat image is, and that image can be used for comparison.

To ensure that shop technicians are well trained in all aspects of thermal imaging, Fluke offers shops two days of professional training with the purchase of a Ti20 unit, and additional levels of training if desired. The basic training consists of a week-long course and gives users enough information to spot problems in a piece of equipment. This level of training is provided by several companies. Advanced courses are designed to be application specific.

Portable thermal imagers, such as the Ti20, ease the implementation of in-house thermographic surveys, Blaisdell says. "The instrument targets industrial-maintenance technicians that are not doing thermography on a daily basis and need a camera they can pick up and quickly use after not having done so for a while," says Blaisdell. Ease-of-use is especially important if several shop personnel are sharing one camera, he adds.

While some imagers require that users go through multiple, embedded menu structures, the Ti20 is designed as a simple focus-and-shoot, triggeroperated instrument. Users can manipulate or post-process images on the camera or on a personal computer using software that is included in the equipment package.

Often, the tehcnician conducting thermal imaging is not the person who repairs the problems that might be found. For this reason, Fluke's software lets users download images to a PC for generating reports that can be sent to various repair personnel.

The software also allows for maintenance routing, so shops can create a monthly inspection route, for instance, to check for hot spots. Repair personnel then receive these images and reports via e-mail or in hardcopy.