Most plants realize the importance of condition monitoring and predictive maintenance for at least their most critical equipment. Many have invested in oil analysis or vibration, temperature or ultrasonic instrumentation in efforts to support predictive programs. But most are not using these tools effectively, either because they don’t have the necessary expertise to take, interpret and act on their readings, or because staff shortages, cutbacks and breakdowns keep shifting their predictive programs to the back burner.
Then there are the plants that haven’t started a program because they simply don’t have the manpower or expertise to begin.
Monitoring the condition of power-transmission equipment is conceptually simple: Analyze the oil and/or measure the vibration, temperature or sound levels continuously or at intervals; detect trends that indicate impending failure, diagnose the fault and repair the machinery at your convenience -- before it breaks.
But the devil is in the details. Practitioners must obtaining consistent, comparable readings, recognize what is abnormal despite external variables such as ambient temperature and load, and understand the equipment and its failure modes well enough to turn abnormal readings into a confident, accurate diagnosis and prediction of time-to-failure. They must be able to do this for many components of any of myriad pieces of equipment deemed essential to plant operations.
“When predictive maintenance was first being implemented 20 years ago, people didn’t really understand the equipment,” says Kevan Slater, director of service for lubrication-management services company Schematic Approach (www.schematicapproach.com). They didn’t know, for example, what type of bearings it had, or which parts were brass. That makes it very difficult to interpret vibration readings or oil analysis results.
“When you know the equipment, you can give weight to the results,” Slater says. “There’s nothing worse than telling a roomful of production people you have to take a piece of equipment down, and they don’t believe you.”
Concerns about condition can go beyond equipment reliability. “There’s some increase in concern about safety-related failures,” says Greg Cober, training manager, Warner Electric (www.warnernet.com). “People come to the realization that it’s better to shut a process off intentionally than as part of an accident.” No matter how quickly the equipment might be brought back online, “It takes a while to bring a process back up from a crushed finger,” he says.
Some of the information required to implement effective condition monitoring is plant- and application-specific; much of it is peculiar to the equipment itself. So why should users have to develop so much of the necessary equipment-specific knowledge? What are power transmission component suppliers and vendors of industrial machinery doing to facilitate predictive maintenance?
A little help from your OEMs
Most equipment OEMS have been slow to provide built-in condition-monitoring capabilities. You might think it’s because they make more money selling service contracts, parts and replacement equipment than they would if their customers could predict failures, but they say it’s a matter of cost and demand.
“Machinery OEMs tend to be very good at mechanical design and metal cutting, but they’re not very familiar with electronics and software,” says Jim McGuinness, Pump SystemAlert program manager, Texas Instruments Sensors and Controls Group (www.ti.com). Some say they want a nonintrusive smart device that can be embedded in a piece of equipment and give information about its condition, but very few are willing to pay for it. They’re waiting for end users to demand it; meanwhile they see it as R&D money with no return.
“End users have to drive this,” McGuinness says. “OEMs are not going to spend any money where they don’t see the return. If users start to insist, OEMs may start picking it up.”
So far, it’s essentially been the local facility’s concern if it wants to do condition-based maintenance, says Ralph DeLisio, business unit manager, integrated condition monitoring, Rockwell Automation (www.rockwell.com). “Most products do not come from OEMs or manufacturers with that ability as standard. But as the cost-per-channel is coming down, some OEMs are starting to offer it as an option.”
Vendors of basic power transmission components like belts, chains, clutches and cylinders do little to facilitate condition monitoring, focusing instead on making their products durable and making sure they’re used properly. “We don’t have customers beating down the door wanting to do predictive,” Cober says. “But they are trying to get longer lives out of our clutch and brake components.”
In the area of drive belts, “We’ve had some discussions about integrating some technologies to improve predictive maintenance, but we concentrate on reducing maintenance requirements and increasing durability,” says Justin Aschenbrenner, vice president, power transmission development, Gates (www.gates.com). “In a lot of cases, belts have been misapplied. People need to get a design that works on the piece of equipment, and we have teams whose job is to get the right design on the application.”
On the other hand, even a simple conveyor belt can warrant a $30,000 condition-monitoring system if it’s big, expensive and critical for plant operations.
“One of our power plant clients has a 12,000-ft. coal feeder belt that’s absolutely essential for keeping the plant running,” says Tom Armold, vice president, product management and marketing, Applied Industrial Technologies (www.applied.com). “If an idler breaks, it can tear the belt for 5,000 ft., which costs as much as a million dollars for the belt plus installation, and takes eight days to repair.”