Magnets are an extremely useful tool for a wide variety of applications, from holding notes and pictures to your fridge to powering large complex machinery. However, finding the right magnet for your application can be a daunting task.
With so many shapes, sizes, and materials to choose from, each with its own unique properties where do you begin to select your magnet.
Well luckily for you we’ve got some guidance on how to choose the right magnet for your project, including information on magnet size, shape, strength, and material.
Magnet Strength
The first thing to consider when choosing your magnet is its strength, the strength of a magnet can be measured in Gauss or Tesla, with higher numbers indicating stronger magnets.
However, the pull strength of a magnet is another measurement of strength, a magnet’s pull strength is the force that’s required to pull that magnet straight free vertically from a steel plate.
The strength of the magnet you require will be completely dependent on your application, for advice please be sure to contact our team for free no obligation advice.
Magnet Size
An important factor is the size of your magnet, this may already be determined by specifications from your application, but finding a magnet the correct size is an important step in choosing your magnet.
Typically, smaller magnets are weaker but are more versatile and easier to use in certain applications, whereas larger magnets are stronger and better suited for heavy-duty applications, but they can be more expensive.
Magnet Shape
Magnets come in many different shapes, including bars, rings, discs, horseshoes, cubes, and rectangles, the shape of the magnet you choose will have a direct impact on its usefulness.
The shape of the magnet you require will be dependent on your application, for example, a disc magnet may be used for more mechanical projects whereas horseshoe magnets are more commonly used for holding objects.
Magnet Material
Magnets come in a variety of different materials, each with its own unique properties. The most common magnet materials are neodymium, ferrite, alnico, and samarium cobalt.
Neodymium magnets are the strongest material available, whereas ferrite magnets are much more cost-effective, samarium cobalt magnets have a greater temperature resistance, and alnico magnets are also very strong.
Temperature Considerations
The temperature which a magnet will have to withstand in your application must be taken into consideration when choosing a magnet. Some magnets lose their strength at high temperatures and others may become permanently demagnetised.
Standard grade neodymium magnets have a maximum operating temperature of 80 degrees Celsius. When heated above this, they will experience irrecoverable losses in performance. High temperature grades of neodymium magnets with higher maximum operating temperatures are available.
Samarium cobalt magnets are not as strong as neodymium magnets at room temperature but have a better temperature coefficient for both remanence (Br) and resistance to demagnetisation (Hci) than neodymium magnets.
Alnico magnets also have the highest maximum operating temperature of all the permanent magnet family, not suffering irreversible losses in performance until the temperature reaches 525°C.
Unique among permanent magnets, ferrite magnets actually become more resistant to demagnetisation as their temperature increases. Conversely, their strength decreases as their temperature rises, albeit at a lower rate.
