by Marjorie Steele, Editor for IQS
The magnet is one of civilization’s oldest and most useful tools. Most people would be surprised to learn how many items and conveniences in our daily lives are made possible by magnets. I say most people, but certainly not all; manufacturers of industrial magnets and veterans of the agricultural, mining and metal fabricating industries are well aware of magnets’ many diverse – and essential – uses.
My grandmother, who grew up farming in southern Michigan during the Great Depression, understood what a valuable tool a magnet can be. As a small family farm struggling to survive in extremely tough economic times, her family used the only technology available to them in order to maintain the health of their crops and animals. Their equipment and technology relied on the principles my grandparents’ generation carried throughout their lives: dependability, toughness and simplicity.
The production and handling of crops during that time often left unwanted materials such as rusted nails, barbs or metal equipment fragments in the hay and grain that was fed to cattle. Farmers like my grandmother and her parents recognized how easy it would be for valuable livestock to ingest nails or barbs; left in an animal’s digestive system, rusted nails or metal barbs would likely kill the animal through a nasty internal infection. The farmer’s solution to this common and very costly problem was simple: cattle were fed what is commonly known as a “cow magnet”, which is a very strong, smooth, oblong magnet. It remains in a cow’s stomach in order to collect any metal fragments which might stray into its diet. After a time, the magnet passes through the cow’s digestive system, carrying any rusted nails or metal shards the cow might have eaten along with it. It may sound gross to non-agriculturalists, but it kept cattle and milking cows healthy in a way no other tool could have done.
Always the functionalist, my grandmother kept one of these old cow magnets (which I hope had never been used) in her ample-sized purse to collect the spare change that fell to the bottom. I used to play with the industrial-strength magnet and all my grandmother’s spare nickels and dimes under the church pews on Sunday as a little girl, fascinated by the magnet’s power.
Most of the challenges my grandparents and great-grandparents faced in agriculture still stand for today’s agriculturalists; contamination of crops (and, consequently, of livestock) with metal fragments is still a common concern, even with our more “advanced” modern farming equipment. Mining, plastic fabricating, metal parts fabricating and petro-chemical industries also find metal separation to be an essential part of the manufacturing process, whether the purpose of separation is to weed out contaminants, to sift and separate newly manufactured parts or to safely handle large, awkward metal materials such as metal sheets and plates. Magnets are the key to all these processes. Manufactured in an almost limitless range of sizes, shapes & strengths, magnets are configured into various tools, or “magnet assemblies”, to do the essential work of metal separating, lifting and even creating mechanical motion. Although the source and nature of magnets’ properties remain largely a mystery to today’s scientists, magnets’ uses and capabilities are harnessed in every way imaginable to do work which could not be done any other way.
Although the list of different magnet assemblies and magnet applications is almost endless, there are a few basic types of industrial-use magnets and magnet assemblies. A broad, cursory list of magnets’ most common applications are as follows:
- Separation and Sorting – such as magnetic “grate separators”, used commonly in agriculture, food production, plastic fabrication and chemical processing to glean out any metal fragments which might have fallen into free-flowing products
- Lifting – common assemblies include “pickups” and “sweepers”; these magnetic lifting tools can lift anything from large numbers of industrial fasteners to coiled steel rolls, making material metal handling faster, easier and safer
- Holding – metal sheet and plates are often placed in “sheet fanners”, a group of fanned magnetic plates which effectively hold fabricated metal sheets upright to avoid warping and scratching
- Conveying – magnetic conveyor belts filter out metal scraps or products and/or carry them where they need to go. The conveyor belt I mentioned in “Conveying Systems: Rolling Cheese Downhill in Safety” that lifted bolts up an incline is a prime example of magnetic conveying
- Water Filtration – one of the unexpected properties of permanent magnets is their ability to “ionize” water that may be especially hard; water filters designed for this purpose pull metallic elements and minerals out of water, making it not only safer to drink, but also eliminating mineral buildup inside pipes and plumbing
- Electrical/Mechanical – permanent magnets generate motion inside AC (alternating current) and DC (direct current) motors through the mechanical energy created by the introduction of electricity to the magnets’ magnetic fields. AC and DC motors run electric pumps, fans, blowers, and many household appliances
- Sound Amplification – audio speakers use a combination of electromagnets and permanent magnets vibrating against one another to create sound waves
- Medical/Scientific – devices such as Magnetic Resonance Imaging, or MRI’s, polarize atoms in the human body’s blood and tissue, allowing doctors to determine the condition of internal organs and tissues. Other magnetic uses in medical devices include blood separation and improving blood circulation
As you can see from this list, a wide range of properties, including strength, durability and permanence (or nonpermanence) are required to meet all these applications. That’s why there are so many different types of magnets. Permanent magnets, such as ceramic, alnico and rare earth magnets retain their magnetism indefinitely; electromagnets, on the other hand, are only activated (or deactivated) with the introduction of an electric current. Many large-scale holding magnets, such as the magnetic pickup crane you might see in a junkyard, are electromagnets. The electromagnets in junkyard cranes and hand-held pickups are activated as long as holding is required, then the electric current is disconnected and the magnets release their hold.
For applications requiring permanent magnets, there are several types with various properties of strength and durability under harsh conditions. Ceramic and alnico magnets are cost-effective and fairly easy to manufacture, but their holding power and the durability of their magnetic fields (often called “magnetic permanence”) don’t begin to compare to that of rare earth magnets. For example: compare the magnetic strength of a handful of magnetic marbles (which contain ceramic magnets) to that of a cow magnet (usually made from alnico, an aluminum-nickel-cobalt alloy). Neither of these compare to the pull of neodymium or samarium cobalt rare earth magnets, which you’re not as likely to find lying around the house (unless you tear apart your computer). If you’d like to learn more about the different types of magnets and their applications, try visiting our Magnet Assembly info pages. Or, if you’re in the market for industrial magnets and magnetic tool assemblies, ask a magnet manufacturer what type of magnet would be ideal for your specific application.
In all the technological and industrial advances that have been made over the last century, I find it ironic that nature’s most basic forces remain the most useful. Hydraulic force (water), pneumatic force (air), heat energy and magnetic power drive the manufacturing world, and many of our daily conveniences as well. From the tiny neodymium magnet in your computer that reads and stores information to the plated alnico magnets in a cow’s stomach, it seems that the staple technology of yesterday is the foundation of tomorrow’s technological advances.