FAQ - Frequently Asked Questions
What temperatures can magnets withstand?
- the magnet material used (neodymium or ferrite)
- the magnet's temperature type
- the magnet's shape
- the positioning of magnets in a group
Types of temperature losses (= loss of magnetisation due to high temperature)If you heat up a magnet above its so-called "maximum working temperature", it loses part of its magnetisation. Thereafter, it adheres less strongly to an iron plate, for instance, even after the magnet is cooled down again. At a certain temperature, the so called "Curie temperature", there is no remanence left.
Reversible temperature loss
- Temperature area: just above the maximum working temperature
- The magnet is less magnetic as long as it is hot.
- Once it is cooled down, it regains its original strength.
- It makes no difference how often the magnet is heated up and cooled down.
- Temperatur area: significantly above the maximum working temperature
- The magnet is weakened permanently, even after it is cooled down.
- Repeated heating at the same temperature does not amplify irreversible losses.
- Remagnetising an irreversibly weakened magnet through a strong enough external magnetic field can give it its original strength back.
Permanent lossAround the Curie temperature, the structure of permanent magnets starts to change. Remagnetising is no longer possible.
All before-mentioned types of temperature losses are covered in the following video. The author differentiates between "warming up" (reversible), "heating up" (irreversible) and "smouldering" (permanent). At the end, a magnet is melted. It is hardly a surprise that therafter it does not possess any magnetisation anymore.
Duration of heatingThe duration of heating has only a minimal influence on the strength of losses when it comes to irreversible losses, given that the temperature was the same everywhere on the inside of the magnet. When heating up a thick magnet for a short time, the outside temperature may be much higher than the maximum core temperature inside the magnet. In that case, temperature losses are dependent on the position - the magnet is therefore irregularly magnetised.
Magnet shape, direction of magnetisation and positionWhether heating leads to irreversible losses depends not only on the temperature type of a magnet but also on the following three factors. The maximum working temperatures are therefore only reference points.
Magnet shapeThe indicated maximum temperature is only valid when the width-to-height ratio of the magnet is "ideal." The following rule applies: A very thin or flat (flatness = diameter divided by height) magnet already suffers irreversible losses at temperatures below the maximum working temperature.
Direction of magnetisation with ring magnetsDiametrically magnetised ring magnets possibly have a much lower maximum working temperature. We recommend prior tests if the magnets will be subject to higher temperatures.
Positioning of magnetsThe more a magnet in a certain position is exposed to a reverse field, the lower is its actual maximum working temperature.
Features of neodymium magnets
|Temperature type||Max. working temperature||Curie temperature|
5 pcs. 0,80 EUR ea.*Block magnet 22 x 8,5 x 1,4 mm
5 pcs. 1,04 EUR ea.*Block magnet 25 x 6 x 2 mm
1 pc. 4,65 EUR ea.*Block magnet 30 x 15 x 6 mm
20 pcs. 0,27 EUR ea.*Block magnet 5 x 5 x 1 mm
20 pcs. 0,27 EUR ea.*Block magnet 5 x 2,5 x 2 mm
20 pcs. 0,27 EUR ea.*Block magnet 5 x 2,5 x 1,5 mm
10 pcs. 0,34 EUR ea.*Block magnet 6 x 4 x 2 mm
20 pcs. 0,34 EUR ea.*Block magnet 6 x 5 x 2 mm
10 pcs. 0,37 EUR ea.*Block magnet 10 x 3 x 2 mm
10 pcs. 0,65 EUR ea.*Block magnet 12 x 7 x 2 mm
5 pcs. 1,41 EUR ea.*Block magnet 30 x 7 x 2,5 mm
10 pcs. 0,61 EUR ea.*Block magnet 15 x 4 x 4 mm
Features of ferrite magnets
|Temperature type||Max. Working temperature||Curie temperature|
|Y35||250 °C||450 °C|