Dennis O’Leary - doleary@magnetics.com
For longer than most (if not all) magnet manufacturers would care to admit, separators didn’t exactly hover at or near the top of most plants’ equipment priority lists. However, the last decade has seen significant momentum that has clearly swept magnetic separation equipment into the discussion when either designing a new facility or retro-fitting an existing one. Why?
For starters, the use of rare earth material in creating the magnetic circuit became a mainstream alternative to the industry standard of ceramic. This opened the door to stronger circuits, unique design options, and a much broader range for processors from which to choose. Thankfully, this effectively ended the "a magnet is a magnet" era. Like its ceramic counterpart, rare earth is strong but it also offers greater ability to hold the captured ferrous metal and weakly magnetic contaminants to prevent them from "washing off" back into a cleaned product stream; rare earth is also roughly 15 times stronger than ceramic. When an application requires a minimum holding value that cannot be accomplished with ceramic due to dimensional constraints (structural, stack-up, or otherwise), the higher strength-to-size benefit of rare earth can play a positive role. The general rule of thumb says rare earth is for consumer product protection and ceramic is for capital equipment protection.
The relevancy and enforcement of HACCP and related QA/QC programs has been an effective driver for magnetic separators as well. The use of separators to target upstream contamination points is certainly a cost-effective alternative to waiting until the final product has been presented for packaging or - worse yet - is at the end user. The shift that continues to occur as a result of these programs is the push up the supply stream for a cleaner product. Just some of the positive changes resulting from this shift include: increased plant efficiency, reduced downtime, less capital equipment repair, and streamlined preventative equipment maintenance schedules. Every one of these examples is traceable, tangible, and provides value to the bottom line. Unless a company is 100% vertically integrated - creating, planting, harvesting, producing, processing, packaging, and acting as the ultimate end user of the product - it is reasonable to make an assumption that somewhere on that supply stream there exists a real opportunity for contamination - intentional or otherwise - that should be addressed. Rail cars, bulk trucks, storage silos, processing equipment, box cutters, and tools are all prevalent in the supply stream and all proven again and again to be prime culprits for ferrous contamination.
The broad popularity that metal detectors gained at the start of this millennium had a positive impact on how facilities viewed the use of magnets. It didn’t take long for many plant operators, engineers, and maintenance personnel to realize this was an effective one-two punch; it was usually shortly after the detector discharged a massive amount of clean product into a bin or onto the floor because of a small piece of ferrous metal. The fix was in: placing the magnetic separator upstream from the detector, thereby minimizing the number of "trips" or rejections of the detector since the vast majority of contaminants are of the ferrous nature.
Forget about food for a moment since that always seems to be the hot button reference. It almost feels like a guilt-trip sales pitch: "If it’s a food plant you’d better have magnets". Perhaps the concern is metal fines resulting from the friction on a piece of processing equipment to minimize the chance of a flash fire. Most processing equipment is manufactured from 400 series stainless steel which by its very nature is weakly magnetic; the shavings and fines whose metallurgic properties have changed as a result of the friction now become much easier to capture. The point is this: broadening the thought process on magnetic separators with an honest assessment of the necessity for this equipment is a pain-free process that every facility ought to undertake. While that audit process isn’t going to provide any financial value, the results of the process most assuredly will and that is the value proposition.
Dennis O’Leary is General Manager for Industrial Magnetics, Inc. (Boyne City, MI), a provider of both permanent magnets and electromagnets for work holding, lifting, fixturing, conveying, and magnetic separation.