In the world of neodymium magnets, the air gap refers to the precise distance separating a rare earth magnet and its intended attachment surface. In most cases, this intended surface would be another magnet or ferromagnetic object, such as a steel disc.
Air gaps are a big deal because they give you an effective way to manipulate, calibrate and control the strength or pull force of a magnet and magnetic attachment in your application.
The way it works is relatively simple: if you want a magnet to perform with its maximum pull force, it has to be as close as possible to another magnet or ferromagnetic surface. That means little or virtually no air gap.
As you move a magnet incrementally away from its intended attachment source, you increase the air gap and thereby proportionally decrease the perceptible pull force of that magnet. So, more air gap means less perceptible magnetic pull force.
The air gap doesn’t have to be just air. It could be card stock, rubber, aluminum, fabric, plastic, leather, vinyl, or wood.
Generally, when we talk about air gaps in relation to magnets, we're referring to the space or distance between a magnet and another ferromagnetic object or surface.
The term "air gap" might also be a bit misleading, though, because the gap doesn't necessarily have to be made up of air. It could be made up of any non-magnetic material like wood, leather, aluminum, rubber, ceramic, card stock, fabric, vinyl or plastic.
And again, the type and thickness of this material creating the air gap would also have a major impact on the magnet’s pulling force measured on the other side of the gap. This means you can easily adjust the strength of a magnet’s pull by decreasing or increasing the thickness of the material utilized in the air gap.
A magnet’s magnetic pull force jumps or drops dramatically at even a millimeter or two of distance.
Understanding the role of air gaps is crucial to effectively harness the power of neodymium rare earth magnets in a wide range of applications, from elegant purses to powerful engines and high-resonance MRI machines.
Magnets possess a unique and remarkable property called a magnetic field, an invisible force emanating from the magnet that attracts or repels other magnets and magnetic materials, and this magnetic field is responsible for the physical interactions we observe between magnets and other objects.
So here’s where the air gap comes in. This magnetic field is at its strongest right at the surface of a magnet, but quickly diminishes at even the smallest distance or air gap away from the surface of the magnet itself.
So now, when there is an air gap between two magnets or a magnet and another object, it affects the strength of the magnetic field. In simple terms, the larger the air gap between two magnets, the weaker their magnetic attraction or repulsion will be.
Or, put another way, if you have two magnets close together, they will have a stronger attraction/repulsion compared to when a larger air gap separates them.
Why Air Gaps Are Important
This concept of air gaps is very important in various applications involving magnets. This is because by being able to add or subtract air gaps or distances between magnets, you can achieve just the right holding power with a desired magnetic attachment.
For example, in purses, backpacks, and other luggage-related products, you want the appropriate air gap between the magnet in the body and the magnet or steel disc in the foldover cover/strap. You want the hold to be strong enough to hold the purse backpack closed if it is dropped, but easy enough to open in normal use. You want what is called the right amount of tension.
To get the right amount of holding power or tension between the purse or backpack body and closure flap, it is helpful to be able to manipulate the air gap. By adjusting the gap with leather or another material to increase or decrease the distance between the magnets in the body and foldover flap, you can make the holding tension on the purse or backpack secure and feel just right.
Another example on the importance of air gaps can be found in electric motors or generators. The distance between the magnets and the rotating shaft needs to be carefully controlled to ensure efficient energy conversion. In magnetic resonance imaging (MRI) machines, the positioning of magnets and the patient's body is crucial to obtain accurate images, and air gaps can affect the quality of the results.
Need More Information?
Air gaps play a significant role in how magnets interact with each other and other objects. And by controlling the air gap, you control the magnet and the strength of attachment - enabling you to envision, design and optimize various devices and systems to utilize magnets most efficiently and effectively.
If you have any additional questions about how manipulating air gaps can affect magnet performance in your application, please feel free to get in touch with us, and we'll be happy to help.