Permanent Magnets
Distribution
RARE EARTH MAGNETS - NEODYMIUM AND SAMARIUM-COBALT
TECSA supplies a line of permanent magnets in different materials, sizes and coatings. Rare earth magnets made of neodymium or samarium-cobalt are extremely strong and powerful magnets for their small size. They are also highly resistant to demagnetisation and high energy fields, making them ideal for miniature applications.
These magnets must be coated in nickel, zinc, tin, copper, epoxy, silver or gold to protect them and to reinforce them against corrosion and humidity. These coatings do not directly affect the magnet’s strength nor its properties.
KEY FEATURES:
Very high remanence (resistance to external magnetic fields) and coercivity (resistant to demagnetisation).
Excellent magnetic properties, high efficiency and low cost
Highly flexible compared with conventional magnets such as ceramic, alnico, SmCo and Ferrite.
Temperature limit: 200 ºC
Propensity to oxidise in humid conditions, a coating is recommended.
PRIMARY APPLICATIONS:
The magnets are able to transform electrical energy without loss of electrical property. These effects may be useful in applications such as electrical motors, speakers and equipment requiring variance in the motion of charged particles. Other effects:
Mechanical-electrical effects for generators, motors and microphones
Mechanical effects for heating Foucault currents (turbulence or Eddy currents) and hysteresis devices for torque control
Mechanical-mechanical effects for magnetic separators, sensors and detectors
Other magnetic-resistant effects.
ELECTRONIC: sensors, hard drive discs, switches, electro-mechanical devices
AUTOMOTIVE. direct current engines (hybrid and electric), small high-performance engines, hydraulic steering
INDUSTRY: lifts, pumps, heaters, battery chargers, domestic appliances, electro-valves, fans
MEDICAL: Magnetic resonance equipment and scanners
CLEAN ENERGIES: improvements to water cycles/flow, wind turbines
MAGNETIC SEPARATORS: recycling and waste removal
MAGNETIC BEARINGS
ORIENTATION AND MAGNETISATION
The direction of the orientation or axis is the direction in which its magnetism is the greatest.
Orientated/anisotropic: have a preferred direction of magnetism
Non-orientated/isotropic: can be magnetised in any direction
Poles: points where the magnetic force is centred identify north and south.
Magnetisation: requires very strong magnetic fields They can be magnetised in any direction provided they are correctly aligned. If multiple magnetisation is required, special equipment is needed.
ADDITIONAL INFORMATION
Maximum temperature?
Their limit is 200ºC Therefore, various grades and specifications are developed for each operation. Before selecting a neodymium magnet, it must be clear what the maximum operating temperature of each application will be.
How long do they maintain their magnetic force?
As long as they are not exposed to excessively high external magnetic fields that cause demagnetisation and/or exposed to temperatures higher than their limit, the magnets will not lose any of their force.
If they have been demagnetised, can they be remagnetised?
It depends on how they have lost their magnetism. Magnets can generally recover their original force, unless they have been exposed to extreme heat.
Do magnets become weaker? How?
If your magnet is kept close to heat sources, strong electrical currents, other magnets or radiation, it may lose its force. High humidity may corrode neodymium magnets. Rare earth magnets are very resistant and difficult to demagnetise compared to most other magnets. They do not lose their magnetism if they are dropped or are kept close to other magnets, but they begin to lose their force if heated above their working temperature, which is 80ºC for standard N grades. They will lose their magnetism completely if they are heated above their Curie temperature (590ºC) for standard N grades. Some magnets have been designed to support very high temperatures without losing their force.
OTHER MAGNETS
ALNICO
As their name indicates, ALNICO magnets are made mainly of aluminium, nickel, cobalt and iron. Their key characteristics are their excellent magnetic stability and resistance at high temperatures, up to 500ºC, as well as their high remanence and heat stability. They are also non-corroding and do not require coating.
ALNICO magnets can be produced by casting or sintering, the latter producing magnets with superior mechanical resistance.
Some of their applications include: ignition magnets, motors, distributors, relays, controls, generators, receivers, separators, radars, coin machines, clutches, bearings, telephones, microphones, speakers, security systems.
FERRITE
Ferrite or ceramic magnets are the most common types. They are easy to process and their raw materials are cheap. They are resistant to high temperatures, non-oxidising, and are resistant to demagnetisation (corercivity) and corrosion. They can be found in many forms: blocks, discs, rings, arcs and sticks
