About Magnets

About Magnets
A magnet is a material or object that produces a magnetic field.

In physics, magnetism is one of the phenomena by which materials exert attractive or repulsive forces on other materials via their magnetic field. Magnetism occurs when electrically charged particles are in motion, which creates a magnetic field.

Magnetic Fields & Magnetic Poles
Normally, magnetic fields are seen as dipoles, having a "South pole" and a "North pole"; terms dating back to the use of magnets as compasses, interacting with the Earth's magnetic field to indicate North and South on the globe.

For historical reasons, the "end" of a magnet that points towards the North Magnetic Pole is itself called the "north pole" of the magnet, with the other end being the magnet's "south pole". Because it is unlike poles that attract, the Earth's North Magnetic Pole is therefore physically a magnetic south pole. To avoid confusion between geographic and magnetic north and south poles, the terms positive and negative are sometimes used for the poles of a magnet. The positive pole is that which seeks geographical north.

The true North Pole is one of the two points where Earth's axis of rotation meets the Earth's surface. The other point is the South Pole. So if you are heading to the true north, you should arrive the true North Pole. However, the Magnetic North Pole is the direction a camass indicates, which at one point will direct you downwards, towards the core of the earth. The Magnetic North Pole is changing, and has 'travelled' more than 1,100 km in the last century.

Measuring Magnetic Fields
Calculating the attractive or repulsive force (measure the flux density) is an extremely complex operation, as it depends on the shape, magnetization, orientation and separation of the magnets. Since it involves measuring the movement of electric particles in materials, the following factors are needed to be considered: size, mass and distance.

There are three main unit standards for measuring the flux density.

1. The CGS method, which uses the following units: Centimetres, Grams and Seconds. The measure unit is called gauss.

2. The SI method, which uses the following: Meters, Kilograms and Seconds. The measure unit is called tesla.

3. The English method, which uses the following: Inches, Pounds and Seconds. The measure unite is called Lines/in.

The first method which uses gauss is the most popular for indicating the strength of the magnets / magnetic field in magnetic jewellery. We use this measuring unit to indicate the strength of the magnets in our Magnetic Bracelets (Titanium Magnetic Bracelets, Stainless Steel Magnetic Bracelets, Gold Magnetic Bracelets, All-Magnets Bracelets, Golfers Magnetic Bracelets, Copper Magnetic Bracelets, Stone Magnetic Bracelets, Alloy Magnetic Bracelets, Expanding Bracelets and our Extra Large Bracelets), All our Magnetic Bangles Titanium Magnetic Bangles, Silver Magnetic Bangles, Stainless Steel bangles, Copper Magnetic Bangles and the Economy Magnetic Bangles), our other Magnetic Jewellery (Our Magnetic Rings & Earrings, Magnetic Necklaces and chains, Magnetic Hematite jewellery and our Watches with magnetic bracelets), our Magnetic Therapy products (The General Magnetic Well-Being products and the Magnetic Body Support), and our Magnetic Animal Care (Pets Magnetic Care).

Ferromagnetic materials can be magnetized in the following ways:

1. Placing the item in an external magnetic field will result in the item retaining some of the magnetism on removal.

2. Placing the item in a solenoid with a direct current passing through it.

When magnetizing objects, the results will be considered to be "soft" or "hard":

1. A "soft" or "impermanent" magnet is one that loses its memory of previous magnetizations. "Soft" magnetic materials are often used in electromagnets to enhance (often hundreds or thousands of times) the magnetic field of a wire that carries an electrical current and is wrapped around the magnet; the field of the "soft" magnet increases with the current.

2. A "hard" or "permanent" magnet is one that stays magnetized for a long time, such as magnets often used in refrigerator doors and magnetic jewellery. Permanent magnets occur naturally in some rocks, particularly lodestone, but are now more commonly manufactured.

A magnet's magnetism decreases when it is heated and increases when it is cooled.

Types of Magnets and Materials

1. Ferrite Magnets:
Ferrites are usually non-conductive ferromagnetic ceramic compounds derived from iron oxides such as hematite or magnetite as well as oxides of other metals. Ferrites are, like most other ceramics, hard and brittle. In terms of the magnetic properties, ferrites are classified often as "soft" and "hard" which refers to their low or high coactivity of their magnetism, respectively.

Permanent ferrite magnets (or "hard ferrites"), which have a high permanence after magnetization, are composed of iron and barium or strontium oxides. In a magnetically saturated state they conduct magnetic flux well and have a high magnetic permeability. This enables these so-called ceramic magnets to store stronger magnetic fields than iron itself.

Ferrites are produced by heating: an intimate mixture of powdered precursors are heated and pressed in a mould.

2. Alnico Magnets:
Alnico alloys make strong permanent magnets, and can be magnetized to produce strong magnetic fields. Of the more commonly available magnets, only the rare-earth magnets such as neodymium and samarium-cobalt are stronger. Alnico magnets produce magnetic field strength at their poles as high as 1500 gauss.

Alnico magnets are produced by casting or sintering processes. Anisotropic alnico magnets are oriented by heating above a critical temperature, and cooling in the presence of a magnetic field.

3. Neodymium-iron-boron (NdFeB) magnets:
NdFeB rare-earth magnets are actually the second generation of Neodymium rare-earth magnets. They are very strong in comparison to their mass, and are made from sintered neodymium, iron and small amounts of boron. These magnets have the highest energy product of any permanent magnetic material. The biggest problem with NdFeB magnets is that they are mechanically fragile and start losing strength as their temperature approaches 80C (170F). For this reason, THOSE MAGNETS ARE NOT SUITABLE FOR SILICONE BANDS - because they will loose most of theirs strength when the silicone in being injected and sealed around theme. Another big issue is that their Iron content makes them susceptible to corrosion. For this reason, they are usually plated, to protect them from corrosion. The problem in plating the magnets is that plating may be chipped and may fall off, which exposes the magnets of the typical magnetic bracelet, magnetic bangle, magnetic ring and magnetic chain to the humidity of the skin.

4. Samarium-cobalt magnets:
A sintered rare-earth magnetic material made of samarium and cobalt, those magnets are more expensive and not as powerful as neodymium magnets. However, samarium-cobalt magnets are higher temperature resistant and can be used for higher-temperature applications, as they do not begin losing strength until they approach 250C (482F). This made those magnets THE BEST CHOICE TO USE IN SILICONE MAGNETIC BANDS, as they will not loose their strength during production time, when the hot silicone is being made around them and in the process of sealing the bands. Those magnets are also better resisting corrosion, which makes them a choice of many people that buy magnetic bracelets or magnetic bangles, as the humidity of the skin is likely to effect them less.

5. Ceramic magnets:
Magnets that are made of Alnico alloys (composite of iron oxide and barium/strontium carbonate) are strong permanent magnets, and can be magnetized to produce strong magnetic fields. Of the more commonly available magnets, only rare-earth magnets such as neodymium and samarium-cobalt are stronger. Alnico magnets produce magnetic field strengths at their poles as high as 1500 gauss (0.15 tesla).

Alnico magnets are produced by casting or sintering processes. Anisotropic alnico magnets are oriented by heating above a critical temperature, and cooling in the presence of a magnetic field

6. AlNiCo magnets:
A magnet made from aluminum, nickel and cobalt. Although these are brittle, they are corrosion-resistant, and have an extremely high 800C (1472F) Curie point (de-magnetization).

7. Injection Molded/Bonded magnets:
A magnet made by the combination of resins and magnetic powder to form a soft and flexible magnetic material.

8. Plastic magnets:
A plastic magnet is a non-metallic magnet made from an organic polymer. The magnetic properties arise from the fully pi-conjugated nitrogen-containing backbone combined with molecular charge transfer side groups. Plastic magnets have uses in computer hardware, for example as disc drives and in medical devices such as pacemakers and cochlear implants where the organic material is more likely to be biocompatible than its metallic counterpart