Check list for magnet performance

  • Operate within specified duty cycle ratings
  • Turn off magnets when not in use
  • Reduce air gaps before lifting
  • Avoid lifting hot materials if possible
  • Do not exceed recommended voltages
  • Inspect for shorted or grounded coils
  • Rotate hot magnets on a "buddy system"
  • Repair cracked casings and damaged connections
  • Correct or replace faulty controller components
  • Do not abuse the magnet
  • Keep magnets away from water
  • Store magnets off the ground

Alliance, Ohio - Lifting magnets are important revenue generators in most scrap metal yards. Suspended from the business end of primary material handlers, magnets are a critical link in the productivity of processing and shipping operations. But, according to one industry expert, few recyclers are actually getting their money's worth from their magnet investment!

Paul Predagovic is the Director of Engineering & Production at Winkle Industries, a leading producer of lifting magnets for both recycling and steel mill applications. "Magnets are one of the most poorly understood pieces of material handling equipment," he claims. "They can be incredibly reliable and potentially last for many, many years of service. Instead, we find that working magnets chronically underperform and are often costly from a maintenance standpoint."

Remanufacturing and recertifying magnets is a major line of business at Winkle, based in Alliance, Ohio. The Winkle plant would see less rebuild work, Predagovic says, if yard owners and machine operators had a better understanding of how to care for their magnets.

His most important words of advice for reducing maintenance costs?

"Just cool it!" Predagovic explains that heat is the number one factor in premature magnet failure. "Heat, moisture, electrical system faults and abuse can all compromise magnet performance. But heat is by far the leading cause for premature failure."

Richard “Dick" Ptak, P.E., Manager of Magnetics Engineering, frequently assists the Winkle sales team to aid in educating customers on the proper use and care of their magnets. Their mission is to introduce operating and maintenance practices that will help ensure longer, better performance from lifting magnets.

Keeping your cool on the job
The first point of reference in identifying heat-related magnet problems is in the magnet's duty cycle. "The length of time that the magnet is powered up during the lifting cycle is critical. Think of it this way: an average toaster produces 800 watts of heat during its work cycle. A typical 66" to 68" magnet produces nearly 20,000 watts! That's a lot of heat and, unlike the toaster, magnet casings are not typically vented."

Winkle recommends that operators stay well within the manufacturer's recommended duty cycle rating, which should be identified on the magnet's nameplate data tag. Operators often power up the magnet too early in the lift cycle, allowing too much time for it to get hot.

"A hot magnet, running around 270o F, loses up to 25% of its lifting capacity. Waiting 2 or 3 seconds to energize before the magnet reaches the material to be lifted will help to keep the heat down and actually increase the amount of material it picks up," Ptak suggests. "If you set the magnet down on the material and let it crush out some of the air gaps before you actuate it, you can improve productivity."

External sources of heat can be another factor in magnet performance, including the temperature of ambient air and of the material being lifted. There is little you can do to control these temperatures, Winkle admits, but it's for this reason that the company recommends purchasing magnets designed for hot surface work and proper duty cycles.

Over-powering the magnet is one common cause of excessive magnet heat that can be prevented. "Magnets are typically operated at 230 volts DC," says Ptak. "Exceeding the rated voltage even a bit makes a big difference to the amperage running through the coils and the amount of heat the coil generates. Just 20 volts over can produce thousands of watts of damaging heat."

"Buddy Up" for performance
Paul Bean, Regional Sales Manager at Winkle Industries, says that magnet owners can introduce various practices to prevent magnet failures. Simply training operators to be more aware of the magnet's duty cycles can be a big step. "We have a number of clients who now operate their magnets on the 'buddy system" he claims. "Anytime a magnet gets too hot, it comes out of service and a "buddy" magnet replaces it. Within 48 hours, the hot magnet has cooled down and it becomes the new 'buddy' – that way, neither magnet is ever overstressed."

Bean advocates a consistent inspection schedule to take the heat off magnet integrity. Proper inspection programs can reveal breakdown of insulating materials in the coil that can result in hot spots, along with moisture or carbon traces in the coil that can cause excessive heating and electrical grounds to the magnet. Inspections programs can also identify mechanical problems that allow moisture to compromise the magnet through cracks in the case, welds or bottom plates, through damaged leads and terminal boxes. Routine system checks also aid in malfunctions in the magnet controller, such as insufficient contactors, resistors and lead wire that undermine the proper flow of electrical power. "To outsiders, a lifting magnet just looks like a big slab of iron on a chain," he admits. "It's hard to see the sophisticated physics going on inside the unit. But to get ultimate value out of a magnet, you have to recognize it as a delicate piece of equipment and treat it with that kind of respect."

The President of Winkle Industries, Joe Schatz, sees growing interest from customers in magnet maintenance and inspection programs offered by the company. "Improper magnet use increases the odds of leaving a lot of money on the table for recyclers. Heat and Improper use will not only result in premature wear, it will also undercut the productivity of material handling capacity for an extended period of time before the magnet finally fails. That means your crane is underperforming, and whatever it's feeding is under capacity as well. Better magnet habits can really pay off!"

About Winkle Industries

Winkle Industries is a worldwide leader in engineered solutions for users of mill-duty material handling equipment. Capabilities include below-the-hook lifting devices, mill equipment, crane products, engineering services, aftermarket services, machining and fabrication. Winkle’s experience and resources is “raising customer expectations” on a wide range of needs, from innovative product design to customer process improvement. 

2080 West Main Street, Alliance, Ohio 44601
Tel: (330) 823-9730 Fax: (330) 823-9788

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For more information on Winkle Industries and their complete portfolio of products and services, contact:

Mark Volansky
Director of Sales

Winkle Industries

2080 West Main Street
Alliance, Ohio 44601
Ph: (330) 823-9730
Fax: (330) 823-9788
Email: Visit the web site at: