August 23, 2016

4 Min Read
Magnetic Separation Equipment Location is Critical
Dennis O’Leary, chief business development officer, IMI Holdings

No, this is not an article extolling the golden rule to real estate success, but the familiar mantra is applicable to powder and bulk processing applications. Specifically, it is critical to choices made with respect to the selection, placement, and installation of magnetic separation equipment.
    
While the majority of processing equipment has found its physical position in a given manufacturing process stream, magnetic separators occupy the “fringe” in terms of perceived necessity and density.
    
As a manufacturer of magnetic separators, the easy answer to the question “Does my facility need magnets?” is “Yes.”
    
“Why and how many?” is the typical follow-up response. Now we are getting somewhere.
    
The golden rule for magnetic separation: A single magnet in a given location can do one of three things, but it cannot do all three. It’s very much akin to the “fast-good-cheap” conundrum wherein you can have two but not all three. What follows are three common locations and scenarios where magnets are best applied.
    
Incoming inspection: A magnet placed at a location to check for ferrous contamination on inbound raw and related materials (think bulk receiving dock) from the upstream supply chain works to prevent metal from entering into the processing line. This is an optimal location to monitor the quality of inbound goods, run batch checks and generally ensure that what is being introduced to the plant is as clean as possible.
    
Capital equipment protection (Capex): Magnets installed mid-stream are ideal to ensure operational efficiency and protect capital equipment by virtue of keeping the process flow clean and humming along. Minimizing downtime to repair or replace capex investments, filter bags, screens, and sifters due to metal damage equates to higher throughput and profitability.
    
Consumer protection: Magnets placed at end-of-line packaging/bulk load-out locations provide a “final inspection” to ensure that no contaminants - be it fines or large tramp iron like a nut or bolt - leave the processing plant where their discovery in a finished, consumable product could and has been known to have catastrophic results.
    
Having all three of these locations covered by magnetic separators offers you control points – places where the entry point of metal contamination can clearly be narrowed down and pinpointed since there are multiple magnets in use. This makes discovery faster and return-to-production time quicker and more efficient.
    
Myth buster: Metal contamination does not always come from the upstream supply chain. Capex and processing equipment itself is often the culprit which necessitates the use of magnets to capture metal fragments from screen material, fasteners, abrading, and contact-friction surfaces, which create metal fines- among other offenders.
    
On a related note, a general rule of thumb on magnet material selection says if you’re trying to capture large metal objects such as nuts, bolts, screwdrivers, or bailing wire, then a ceramic circuit is sufficient. If the goal is to capture metal fines, weakly magnetic wire and similar contaminants, then rare earth would be the material of choice. There are other magnetic materials such as alnico and samarium cobalt for high-temperature applications.
    
So which option do you choose? It depends on the location and accessibility for cleaning the magnetic separator. Do you want to push a button and it self-cleans? Do you prefer to accomplish that with the use of air, hydraulics, or electricity? Options are plentiful.
    
Magnets are commonly tagged as “auxiliary equipment” and that’s a relatively accurate moniker: The purpose of the equipment is to help and support other equipment. What makes magnets attractive is that they have a low cost to operate versus a significant cost of failure. Should a plant choose to bypass the selection and installation of magnetic separation equipment and subsequently experience a metal contamination incident, it can be financially crippling - notwithstanding the punitive and intangible damage to the brand. Generally, a single magnetic separator may contribute 1-2% of a manufacturing line’s equipment cost and even less as a percentage to clean and operate. So if said separator has a price tag of $20,000, it certainly represents a prudent option that deserves consideration - consideration that I believe in the end would win out over crossing one’s fingers and hoping not to roll snake eyes in terms of metal contamination.
    
Evaluating your existing process for potential weaknesses is like peeling back an onion. But it is worth the time and energy on the part of the plant and the equipment manufacturer to investigate options and create a plan for success. An objective approach to magnet selection and placement is worth the low-cost investment.
       
Dennis O’Leary is the chief business development officer for IMI Holdings (Boyne City, MI), which includes Industrial Magnetics (Boyne City, MI), Prater Industries (Bolingbrook, IL) and Sterling Systems & Controls (Sterling, IL).

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