How Strong Are Neodymium Magnets?
Did you ever have a magnetic disc or a set of bar magnets as a kid? Often used to teach children about magnetism, they may come with a magnetic material such as iron dust which can map the magnetic field lines of the invisible magnet forces. Even sphere magnets have magnetization directions in a north and south pole orientation.
Neodymium magnets, also known as rare earth magnets, are some of the strongest and most versatile magnets available today. These powerful magnets, made from an alloy of neodymium, iron, and boron, are used in many applications and can be found as simple office magnet or in highly specialized industrial equipment. They have super strong pull forces at even small sizes. A rare earth neodymium magnet measuring just a few millimeters and weighing only a fraction of an ounce can have pull forces of many pounds!
Measuring strength by the listed pull force is done by units called Tesla. Neodymium magnets can reach a listed pull force of 1.4 Teslas, while other types typically range from 0.5 to 1 Tesla. This strength is due to the tight arrangement of the crystalline structure of the atoms inside the alloy.
Rare earth neodymium magnets have the greatest pulling strength of permanent magnets yet are synthesized by modern engineering. We use them daily in our smartphones, car speakers, GPS tracking devices, and headsets! You’ll find them as fridge magnets in your kitchen, as a knife holder, or as magnetic sheets holding magnetic tools in your garage.
Read on to discover more about how they are utilized in your everyday life and how their strength matches up with other types of magnets.
What Are 5 Interesting Facts About Neodymium?
- Neodymium rare earth elements are termed as such because they do not form in veins like other metals such as iron or gold. Instead, they are found scattered throughout a section of the earth and require extra work to locate and extract. This is one reason why rare earth mining is concentrated in China, where a large amount of this magnetic material has been found.
- The grade of a neodymium magnet product refers to its maximum energy product, which indicates the strength of the magnetic field. For example, a grade N52 magnet has a stronger magnetic field than an N35 magnetic grade.
- The magnetization direction will vary depending on the shape of the magnet, which is why you’ll find magnetic material shaped like a block magnet, cylinder magnet, or ring magnet. These shapes are often used in applications where a specific magnetization direction is required, such as in magnetic separation or in the construction of Halbach arrays. A magnet calculator can measure magnet forces and show you the strength and field lines of magnets of any size you can imagine. This can be handy when searching for a custom magnet size or shape.
- One disadvantage of this type of rare earth magnet is that they can be brittle and can break or shatter if subjected to a strong impact. This can be mitigated by applying a protective layer, such as an epoxy coating, which can help to prevent breakage and increase the durability of the magnet.
- There are two processes that make a neodymium magnet. Neodymium, iron, and boron are heated in a furnace without melting to liquefaction in a process called sintering, which can then be molded into a shape. For a custom magnet shape or size, the process of bonding is used, where neodymium alloy powder is mixed with a polymer binder.
Fun Fact: Adhesive backing magnets on GPS trackers allow people to secretly track a vehicle without a driver ever knowing!
Where Are Neodymium Magnets Used?
What makes a super strong neodymium magnet so impressive is its strength while molded into such small sizes, making it ideal for use in microphones, speakers, and computer hard disks. In the kitchen, you may already own a magnetic knife holder or magnetic locks for appliances. Fridge magnets utilize magnetic tape self-adhesive magnets to hold up your family photos or your calendar. Rare earth magnetic tools like a magnet sweeper are utilized in the garage for magnet fishing, such as finding loose nails, screws, washers, and other bits and ends you don’t want to step on! Engineers and machine operators may use Hall effect sensors to determine the shape of magnetic field lines or find the strength of magnets to interact with magnet assemblies safely.
What Other Types Of Magnets Are There?
Of the different types of magnets, neodymium is the strongest. However, there are other types that you may have heard of. These include:
Neodymium is a type of permanent magnet, which simply means that they should not significantly lose their magnetization, but the most common industrial magnets are made of samarium cobalt. Samarium cobalt magnets can reach much higher temperatures before reaching a point where it becomes demagnetized, called the Curie temperature.
Temporary magnets are materials such as iron that will react to a magnetic field. Magnetic receptive objects react to the field lines of devices like a magnetic sweeper to be picked up from the ground or measured with Hall effect sensors.
An electromagnet is one that generates a magnetic field through an interaction of electricity with a ferromagnetic material, such as an iron nail or screwdriver. A copper wire may be wound around such an object, and the electrical field is turned on or off to enable or disable the magnetic field.
How Does The Shape Affect The Magnetic Field?
Magnets shaped into various forms affect the magnetization direction. A neodymium disc magnet will have field lines stretching like a balloon from the center point, while bar magnets will stretch in a circle around the poles. Horseshoe magnets have great holding power with their ability to grab an object with both the north and south poles, thereby creating a circuit of magnetism. Flexible magnets like magnetic strips will have an altering field of magnetism, but they are quite useful as mounting magnets for wrapping around a pole or around corners in a workshop.
What Is The Strength Of Neodymium Magnets?
The strength of magnets is typically measured by how much a magnet can hold in pounds, as is the force required to pull a magnet from its fixed position. On average, neodymium magnets are ten times stronger than ceramic magnets and ferrite magnets of the same size and shape.
How strong a magnet holds onto magnetic material depends on the arrangement of its crystalline structure. The tight arrangement of the neodymium alloy was an improvement beyond any previous permanent magnet. Alnico magnets had previously been the strongest permanent magnets. The name refers to the composition, which uses aluminum (Al), nickel (Ni), and cobalt (Co).
Can A Neodymium Magnet Stop A Bullet?
Mythbusters busted this myth several years ago. Bullets are not typically ferromagnetic as they are covered in a copper sheath that is not magnetic. Still, copper will interact with a magnetic field, and as the bullet passed over a row of magnets shot by the team at Mythbusters, it began to spin end over end into the target. Unfortunately, the force applied did not alter the bullet’s path in any meaningful way, so don’t think about lining a vest with neodymium magnets!
Are Neodymium Magnets Safe To Touch?
As an individual metal, neodymium oxidizes as it reacts with the open air. Even when combined with iron and boron to make the standard alloy, neodymium will corrode over time. This is why neodymium magnets left outside eventually lose their shape and turn into a powder.
Neodymium magnets exposed to the air are slightly toxic and can harm the eyes, skin, and respiratory system. This, and the brittle nature of this strong magnet type, is why you’ll find most being rubber coated.
Any powerful magnet application can harm the human body. Magnets, neodymium or otherwise, can pinch your fingers or even break bones with enough magnetic strength. The shear force required to pull the magnet apart from a steel plate can be measured by pounds! This is one reason why neodymium magnets were illegal for a time after children had been hurt from swallowing small bits of magnets.
Do Neodymium Magnets Get Weaker Over Time?
As permanent magnets, rare earth neodymium magnets work perfectly as mounting magnets for creating a temporary magnet out of a steel plate that will hold onto magnetic tools in your garage or workshop. You won’t have to worry about them getting weaker over time, as they shouldn’t lose even 1% of their holding power for over a century of use.
Always take care when handling neodymium magnets. While the magnet may be strong, the brittle nature of the metal can chip and send shrapnel flying when they strike together or against a steel plate, even with an epoxy coating. Wearing thick gloves and eye protection is a good idea, even when playing around with small neodymium magnets
Sage is a freelance writer with a background in information technology.
- How Strong Are Neodymium Magnets?
- What Are 5 Interesting Facts About Neodymium?
- Where Are Neodymium Magnets Used?
- What Is The Strength Of Neodymium Magnets?
- Do Neodymium Magnets Get Weaker Over Time?