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 adhesive force loss due to heatIf you heat 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 has cooled down. At a certain temperature, the so-called 'Curie temperature', there is no remanence left.
Reversible loss of adhesive force
- Temperature range: just above the maximum working temperature
- The magnet is less magnetic while it is hot.
- Once it has cooled down, it regains its original strength.
- It makes no difference how often the magnet is heated and cooled down again.
Irreversible loss of adhesive force
- Temperature range: significantly higher than the maximum working temperature
- The magnet is weakened permanently, even after it has cooled down.
- Repeated heating at the same temperature does not amplify irreversible losses.
- A sufficiently strong external magnetic field can remagnetise an irreversibly weakened magnet and restore it to its original strength.
Permanent loss of adhesive forceAt temperatures around the Curie temperature, the structure of permanent magnets begins to change permanently. Remagnetisation 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, the direction of magnetisation and positionWhether irreversible losses occur when a magnet is heated depends not only on the temperature type but also on the following three factors. The maximum working temperatures of the magnets 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.
Working temperatures of neodymium magnets
|Temperature type||Max. working temperature||Curie temperature|
5 pcs. 1,04 EUR ea.*Block magnet 22 x 8,5 x 1,4 mm, holds approx. 1,3 kg
5 pcs. 1,23 EUR ea.*Block magnet 25 x 6 x 2 mm, holds approx. 1,7 kg
20 pcs. 0,28 EUR ea.*Block magnet 5 x 5 x 1 mm, holds approx. 350 g
20 pcs. 0,28 EUR ea.*Block magnet 5 x 2,5 x 2 mm, holds approx. 450 g
20 pcs. 0,28 EUR ea.*Block magnet 5 x 2,5 x 1,5 mm, holds approx. 350 g
10 pcs. 0,33 EUR ea.*Block magnet 6 x 4 x 2 mm, holds approx. 640 g
20 pcs. 0,36 EUR ea.*Block magnet 6 x 5 x 2 mm, holds approx. 600 g
10 pcs. 0,76 EUR ea.*Block magnet 12 x 7 x 2 mm, holds approx. 1,3 kg
5 pcs. 0,73 EUR ea.*Block magnet 20 x 5 x 2 mm, holds approx. 1,5 kg
5 pcs. 1,30 EUR ea.*Block magnet 30 x 7 x 2,5 mm, holds approx. 2,1 kg
10 pcs. 0,59 EUR ea.*Block magnet 15 x 4 x 4 mm, holds approx. 1,7 kg
Working temperatures of ferrite magnets
|Temperature type||Max. Working temperature||Curie temperature|
|Y35||250 °C||450 °C|