Neodymium Disc Magnet Field Profiles
By: Andy Robinson, SM Magnetics Account Manager
Disc Magnet Field Views and Uses
The disc magnet: “a flat circular shape where the thickness is not greater than the diameter.”
Used in almost every industry, the shape of a disc magnet makes them versatile and prominent in countless applications and uses. Did you know that your smart phone, tablet and computer have has multiple magnets inside? Or that the medical industry uses disc magnets for drug delivery systems, sensor applications, surgical devices, oral surgical devices, dental equipment, and optical equipment?
This article will look at the two (2) most common questions we receive about disc magnets.
- How do I know what direction of magnetization to use?
- What does the field look like for a disc magnet?
Let’s take a look at the different views and magnetic field profile of neodymium disc magnets.
This first view shows that this disc magnet is magnetized through the thickness. The bright red located on the corners and part of the surface is going <span>to be where the </span>magnets are of highest strength, which is also shown on the scale to the left. This is where the best activity is in an open circuit because each pole is wrapping around to reach the other pole. The various shades of blue indicate a lower, or weaker, magnetic field as the distance from the surface increases. Disc magnets that are magnetized through the thickness are mainly used for holding applications, consumer electronics, medical applications, and consumer goods.
Our next view shows a disc magnet that is not only magnetized through the thickness, but one that has two poles on the same face. This is called a multipole magnet. As you will see in the image, the greatest strength is in red and this time, most of it is at the center of the magnet. This is again because the North and South poles are traveling to each other. Since they are sitting side by side, they do not have far to travel which makes this a hot spot. A disc magnet that is a multipole is great for holding applications. This type of magnetization allows for excellent coupling.
Our final view shows a disc magnet that is magnetized across, or through, the diameter. The greatest strength is on the outside diameter of the magnet. This type of magnetization is perfect for many sensor applications because most sensors do not require large amounts of field strength. Having this type of magnetization allows for good field strength while not shooting the field past the sensor. It is also important to note that some sensors are designed to be pole sensitive. This means that the sensor will only detect a North pole or only detect a South pole. Those that are not pole sensitive will react to either pole. Knowing which type of sensor you are working, and the magnetic field requirements at a specific distance will help determine the correct placement and size of the disc magnet.
If you’re still not sure if you need to use a disc magnet in your application, or which direction of magnetization to use, contact us and we will be happy to assist you in your selection.
About SM Magnetics: SM Magnetics is privately owned company, providing assistance with magnets, magnetic circuit design, engineering support, and production. For more information, logon to our website, www.smmagnetics.com, or contact us at 205-621-8841.