l Inspection standard for permanent magnet

l Purchasing Guide

l Permanent magnet supply direction

l Surface protection and surface coating for the permanent magnet

l Quality warranty

l Safety principle for manual operation of permanent magnet

NdFeB Magnet

Frequently Asked Questions about NdFeB Magnet:

Q:Will my magnets demagnetize if I heat them?

Yes, if you heat them beyond 170 degrees Fahrenheit (80 degrees Celsius) the magnets will quickly loose their magnetic properties. Sustaining these temperatures for a length of time or heating the magnet significantly higher than this will permanently demagnetize it. Other types of magnets such as Samarium-Cobalt have higher heat resistance(below 300 degree Celsius). There are also other types of Nd-Fe-B magnets that are not as susceptible to heat induced flux degradation,H grade could withstand 100 degree Celsius,SH grade 150 ℃ ,UH grade 180℃,and EH grade 200℃.

Q:I would like to get a single pole magnet?

They don’t exist. All magnets have two poles,N and S.

Q:Do magnets pose a health risk?

No, unless you have an internal medical device such as a pacemaker that would be affected by a strong magnetic field. However, Nd-Fe-B magnets are very strong and should be handled with care. These magnets can pinch if allowed to come together against the skin.

 

Q:How thick could the plating thickness of NdFeB be?

Present technology could only plate NdFeB magnet with max.30 microns thickness. as the plating will bubble and come off if it surpass 30 microns.

Q:How are your magnets measured and graded for strength, quality, etc.?

Magnet Strength Measurements (B) --The units for measuring the field strength (flux density) of a magnet are Gauss or Tesla. 1 Tesla = 10,000 Gauss.There are different ways to classify and measure field strength:

B (flux density): This is the measurement (in Gauss or Tesla) you get when you use a gaussmeter at the surface of a magnet. The reading is completely dependant on the distance from the surface, the shape of the magnet, the exact location measured, the thickness of the probe and of the magnet's plating. Steel behind a magnet will increase the measured 'B' significantly. Not a very good way to compare magnets, since B varies so much depending on measurement techniques.

Br (residual flux density): The maximum flux a magnet can produce, measured only in a closed magnetic circuit.They are a good way to compare magnet strength...

B-H Curve: Also called a "hysteresis loop," this graph shows how a magnetic material performs as it is brought to saturation, demagnetized, saturated in the opposite direction, then demagnetized again by an external field. The second quadrant of the graph is the most important in actual use--the point where the curve crosses the B axis is Br, and the point where it crosses the H axis is Hc (see below). The product of Br and Hc is BHmax.very complicated and expensive equipment is needed to plot a B-H curve.

Magnet Quality (BHmax): The quality of magnetic materials is best stated by the Maximum Energy Product (BHmax), measured in MegaGauss Oersted (MGOe). This is because the size and shape of a magnet and the material behind it (such as iron) have a large effect on the measured field strength at the surface, as does the exact location at which it measured.

Coercivity (Hc): This measures a magnet's resistance to demagnetization. It is the external magnetic field strength required to magnetize, de-magnetize or re-magnetize a material, also measured in Gauss or Tesla.

Q:Will magnets corrode if used outdoors?

NdFeB magnets are susceptible to corrosion. The 'Fe' in the name stands for Iron, and it rusts easily as it’s atom is quite active and it’s easily oxidated! Many of our magnets come with a Nickel, Zinc, Gold or Epoxy coating to protect them from moisture. If the coating is damaged , the magnet could rust if exposed to water or humidity.

Q:How are magnets manufactured? Can I make them at home?
Manufacturing: NdFeB magnets are complicated to manufacture. The raw material should be firstly made into alloy, powdered, orientated in magnetic field, shaped, finally sintered. All of the process should be done with the protection of nitrogen. After sintered process, the finished raw magnets should be inspected in terms of magnetic properties, then finally machined to the sizes required and plated with surface coating. To magnetize them, they are placed in a very expensive machine that generates an extremely high-powered magnetic field for an instant, using high-voltage capacitor discharge and coils. The polarity of the finished magnet depends on how it was oriented in the magnetizing machine, and how the particles in the sintered mixture were oriented. So that makes home manufacture impossible. You CAN, however, make a simple steel magnet at home. Take a nail and stroke it with a strong NdFeB magnet 20 or 30 times, ALWAYS moving the magnet in only one direction on the nail. Presto, the nail will be magnetized, although very weakly and it’ll demagnetize shortly.

Q:How can you ship magnets safely? Don't they affect airplane safety?

We take great care when packing orders to see that any magnetic fields are well contained within the box(wooden box or carton) we send them in. We pack very carefully so the external magnetic fields cancel out, and we use steel box liners as needed to insure that every box is safe and non-magnetic to comply with national and international postal regulations. We also test each package before it goes out to be sure it complies with all regulations

Q:How about the application of NdFeB magnets?

Electric motor industry: Permanent Motor, Mini motor(libration motor),Motor for electric bicycle.

Electronic industry: Speakers, Telecommunication, Computer drive,VCD,DVD, CD-ROM, OA equipment, home appliance, meters.

Industry: magnetic separator(used in Food, Mine, Glass and Coal industry),magnetic crane, magnetic salvage and magnetic chuck.

Civil application: magnetic jewelry, toys, magnetic button.

Medical application: Magnetic therapy, Nuclear magnetism resonance, Magnetic health care.

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