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Top 10 FAQ’s about Magnets

Magnet FAQ's

There are many surrounding magnets, What are they? How do they work? What are the different types? The list goes on. Therefore, we’ve answered the 10 most frequently asked questions.

1.How are magnets made?

Today’s magnet materials are made through casting, compression bonding, pressing and sintering, extruding, injection moulding, and also calendaring processes. Once manufactured, majority of magnets also need to be further processed by machining processes, and then assembled. For more visit our assembly and design brochure.

2.What are the different types of magnets available?

There are three different types of magnets available: permanent magnets, temporary magnets, and electromagnets.

  • Permanent magnets produce a magnetic field without the need for any external source of electrical power.
  • Temporary magnets only act as magnets when they are attached to something that produces a magnetic field. Therefore, they lose this capability when the source of the magnetic field is detached.
  • Electro-magnets need electricity to act as a magnet.

3.What are Rare Earth Magnets?

These are magnets made of the same rare-earth group of elements. Though the most popular rare-earth magnets are neodymium iron boron (NdFeB) and samarium cobalt (SmCo).

4.What are permanent magnets made of?

Permanent magnets are made from distinct alloys that essentially create better magnets. Although, the most common families of permanent magnet materials today include alnico, ferrite, neodymium-iron-boron, and samarium-cobalt.

5.How do I order magnets?

There are many aspects that need to be considered when ordering the correct magnets to suit your application. However, the most important considerations include:

  • General nature of application – is it for holding, moving or lifting?
  • Shape of magnet desired – disc, ring, rectangle etc.
  • Size of magnet desired – it’s diameter, length, width and height
  • Tolerances – what difference in dimensions is allowed?
  • Conditions in which magnets will be used – the temperature, outside, inside, etc.
  • Required strength of the magnet
  • Quantities required

These particular aspects will also have an impact on the cost that it takes to manufacture the magnets.

6.How are magnets rated?

Magnets are available in different shapes, sizes, colours, etc. Therefore, in order to categorize them accordingly they are rated through three characteristics:

  • Residual Induction – this provides an indication of how strong the magnet is capable of being. It is measured in Gauss and given the symbol Br.
  • Coercive Force – this provides an indication of how difficult it is to de-magnetise the magnet. It is measured in Oersteds and given the symbol Hc.
  • Maximum Energy Product – this provides an indication of what volume of magnet materials is required to ensure a given level of magnetic flux. It is measured in Gauss-Oersteds and given the symbol BHmax.

7.What might affect a magnet’s strength?

Many factors have the potential to affect a magnets strength. Although, the most common factors include:

  • Heat
  • Radiation
  • Strong electrical currents near the magnet
  • Other magnets near the magnet
  • High humidity environments will cause neodymium magnets to corrode unless they have a protective coating.

Additionally, it is important to note that shock and vibrations do not affect modern magnet materials unless they cause significant physical damage to the material.

8.Is it possible to make a current magnet stronger?

No, once a magnet is fully magnetised it becomes saturated, and therefore cannot be made stronger.

9.If a magnet has been de-magnetised can it be re-magnetised?

If the magnet material has been damaged by extreme heat then no, the magnet cannot be re-magnetised. However, if the magnet has not been exposed to or damaged by extreme heat then it can be re-magnetised back to its original strength.

10.How long does it take for a magnet to die?

If kept in good, optimum working conditions, a permanent magnet will keep its magnetism for years. For instance, it is estimated that a neodymium magnet only loses approximately 5% of its magnetism every 100 years.

Goudsmit UK

We understand that working with and finding the right magnet can become extremely complex. That’s why our experts at Goudsmit UK aim to simplify the process for our customers by using our experience and also our exposure to a vast number of applications.

At Goudsmit UK we sub-contract manufacture a vast variety of magnets and magnetic assemblies to suit your requirements. Contact us today for more information at dean@goudsmit.co.uk, or if you’d like to speak to a member of our team call us on +44 (0) 2890 271 001.

You can also visit our magnetic products brochure or magnetic grades web-page.

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