Temperature has a variety of effects on magnetic materials
Our customers are always curious about the effect temperature has on the magnets they need. Before you buy, read up on these four common issues. It might help you make a more informed decision when you place your order later today.
How does flux density change when a magnet inhabits very low temperatures?
Flux density of a magnet increases when it operates in extremely low temperatures. The temperature effect is mostly linear over the range of +/- 100C, so electron orbits are shorter and metallic magnets will display an increase in flux density. Ceramic magnets do not.
What happens to the magnet when operating temperatures fluctuate?
Temperature effects in magnets are observed through the atomic structure of the elements making up the alloy. Alloys are made up of atoms, and electrons orbit the nucleus of each atom. As temperature increases from absolute 0, distance between the nucleus and other electrons increases. This increase in distance means each electron has a smaller effect on everything else in the alloy. Magnetic properties of metallic magnets generally decrease in this way.
Will thermal knockdown be an issue in my application?
Magnetic materials are, at all times, as magnetized as their thermal state permits. Prior to magnetization, their magnetic domains arrange randomly to minimize their energy state. Magnetization rotates magnetic domains into common alignment. Permanent magnets retain this alignment to a degree.
Magnetic domains in the center of a magnet support each other, but those domains closer to the sides, ends and edges of the structure have less support. Some are reversed by the magnet's own external field. When heat is applied, longer electron orbits cause all domains to weaken, and those with more exposure to the external field will also reverse.
Thermal knockdown is the process of raising a magnet’s temperature to the temperature expected in the application so any impending change will have occurred prior to installation of the magnet.
To determine whether this process is important for your application, ask a member of our team.
When is heat stabilization important for a magnet?
Magnets are heat stabilized by exposing it to an elevated temperature for a length of time. This prepares the magnet for the irreversible losses of magnetism that it will experience when exposed to elevated temperatures in regular use.
Magnetic loss can be either reversible or irreversible. If reversible, the magnet will simply return to its full strength when it lowers back to room temperature.
The amount of irreversible loss depends on a lot of factors, including the type of magnetic material, shape of magnet, temperature it reached and length of time it sat in the temperature. Each magnet undergoing heat stabilization must be individually handled – a factor in the final cost of the magnet.
To find out more about how extreme temperatures might affect your magnetic material, contact our expert team. We’ll help you make the right decision for your application and ship your product anywhere in the world.