Predictive Maintenance: Taking Motors to the Next Level

Motors and drives are the often-unsung equipment heroes of any manufacturing facility, the components that put and keep operations in motion. Without them, a food or beverage processing plant simply cannot run.

For what seems like an eternity, operators might have taken motors for granted as a wear-and-tear, commodity-type part of the greater puzzle of manufacturing. “Electric motors may appear simple, but they are complex electromechanical systems,” says Alexander Kanaris, president of Van der Graaf (VDG), a manufacturer of drum motors (www.vandergraaf.com).

“The latest electric motor designs focus on achieving premium efficiency for reduction of energy cost and high-power factor. However, the main components of an electric motor have not changed. The stator, the electric motor windings and the rotor are physically the same,” he says. “What has changed is the metallurgical composition of the core and rotor material and the electric motor windings. These changes reduce iron and copper losses, leading to higher overall efficiency.”

Mike Smith, reliability engineering manager for Life Cycle Engineering (www.lce.com), notes, “Almost everything in a plant is run by a motor; the vast majority of things have an electric motor driving them. But it's probably one of the least-understood pieces of equipment that you have in a plant, and it was always treated as, if it quit turning, you removed it and got another one, or took it to be rebuilt.”

He says those tactics stemmed from the fact that most operators never truly understood the inner workings of the motors and how to determine what was truly happening with each unit over time. Of course, in most food or beverage facilities, motors are on the smaller side, relatively speaking (compared to most of the rest of the manufacturing world), so they could be very easily overlooked or ignored. But that was then, and now, the industry has shifted from a “run to fail” mentality to a preventive maintenance approach and onward toward predictive maintenance.

“There had been a lot more focus on preventive maintenance, but now you're really starting to see a hard shift into predictive maintenance,” Smith adds. “A lot of the food & beverage companies are doing predictive analysis — vibration, motor current analysis, etc. — to help get a better understanding of what's going on inside of the motors and drives.”

VDG motors include a sensor called GV-Therm, a bimetal temperature device that will cut the power if the motor exceeds its designed operating temperature. Optional sensors available for VDG Drum Motors include RTDs, thermistors and thermocouples, which primarily are used to sense stator and oil temperature. Sensor bearings and encoders are also available for indexing applications.

The sensors that many processors have installed on their motors are a newer technology in the past decade — an investment that has made sense based on the financial consequences of not being proactive on this technology. When a plant has to stop a processing line or shut down the facility to change out a critical motor, there are ramifications that directly impact the bottom line.

“You’ve got lost production, you've got quality issues and potential safety and environmental issues, and all of that rolls up into dollars lost,” Smith says. “Since food & beverage already runs relatively tight, anything that they can do to improve their return is good business.”

Predictive maintenance boost

Sensors on motors can detect real-time vibration, temperature and other signs of the wear and tear on that component and send that data instantly to be analyzed. Instead of having a maintenance worker walk the floor and record readings once a month or once a quarter, Smith says, operators can get that information instantaneously. Furthermore, because of the innovation in data analytics and implementation of artificial intelligence (AI) systems, processors can get predictive analysis done on a motor or pump in near real-time.

“That gives the maintenance team a long time to prepare for any potential issues,” he explains. “These sensors help maintenance know sometimes months in advance that they have a problem developing, so they can plan and schedule the work.”

That means less unscheduled downtime, more efficiency and fewer quality problems. Quantifying the savings that brings, Smith adds, is the easiest way to get the attention of plant managers, engineers and other decision-makers pointed toward adopting a predictive mindset and listening to what the motors are saying about their own performance. Beyond the dollars saved, there are additional benefits to the strategy.

“The other side of it, which is a bit more intangible, is the improvement in safety and environmental,” he says, “If the equipment is not breaking down, you're not sending people out into abnormal situations to work on equipment unexpectedly.”

Having a finger on the pulse of the motors in the facility can even help create opportunities to upgrade the systems, with motor manufacturers continuing to innovate and develop more premium-efficiency motors. For production lines that are running 24/7, continuously pushing the motors to the limit, swapping out current motors for higher-efficiency models can create a big cost savings due to the reduction in energy use by the new motors.

All VDG electric motors are manufactured to IE4 (premium efficiency standards), says Kanaris. VDG drum motors are about 25-30% more efficient than the traditional external motor and gear box that is commonly used on belt conveyors today. The high efficiency of the VDG drum motor is due to its design, where the electric motor is inline with the gear reducer. In contrast, external motor/gearbox systems typically have the electric motor shaft positioned at a 90-degree angle to the gearbox shaft. This difference results in mechanical losses that can vary between 20% and 40%, depending on the gearbox brand.

The next steps toward further innovation revolve around motor current analysis. Smith says that sensors are available to perform that task today, but they’re not as sophisticated as needed to make a real impact.

“Maybe we'll see that improve in the next year or two, and when that happens, you're going to see a strong push in that direction,” he says. Motor current analysis is just another step toward processors truly understanding the inner workings of the motors they use in their plants — and using that data in conjunction with vibration, temperature and ultrasonics measurements will enhance that expertise.

“One bit of information can steer you in the wrong direction; you want to have multiple indications an issue,” Smith says. “The more evidence you have, the higher confidence level you have that your response plan is correct.”

Of course, without proper systems in place to retrieve, store and handle all that data, then properly produce actionable results, advances in this realm will be slowed down. Processors cannot just throw money at technology and hope it works — there is a human element as well. Smith reminds processors: “If we don't have good processes, we will not be as successful as we should be.”

With the right processes in place, he believes predictive maintenance will be a game-changer for the industry as innovation continues to push the boundaries of what is truly possible in motors and drive technology.