| 1 What information should I provide
when ordering? We will help you with your order. Usually
we ask for the following information.
Material type and grade required.
Size and shape, if available, a sketch or drawing with dimensions
and tolerances.
Max working temperature.
Delivered magnetized or unmagnetized? Magnetization direction?
Quantities required.
Coating required (if any)
Information on what you want to use the magnet for.
2 General information on Neodymium Iron
Boron Magnet Materials Sintered neodymium-iron-boron
(Nd-Fe-B) magnets are the most powerful commercialized permanent
magnets available today, with maximum energy product ranging
from 26 MGOe to 52 MGOe. Nd-Fe-B is the third generation of
permanent magnet developed in the 1980s. It has a combination
of very high remanence and coercivity, and comes with a wide
range of grades, sizes and shapes. With its excellent magnetic
characteristics, abundant raw material and relatively low prices,
Nd-Fe-B offers more flexibility in designing of new or replace
the traditional magnet materials such as ceramic, Alnico and
Sm-Co to achieve high efficiency, low cost and more compact
devices.
A powder metallurgy process is used in producing sintered NdFeB
magnets. Although sintered NdFeB is mechanically stronger than
Sm-Co magnets and less brittle than other magnets, it should
not be used as structural component. Selection of Nd-Fe-B is
limited by temperature due to its irreversible loss and moderately
high reversible temperature coefficient of Br and Hci. The maximum
application temperature is 200 C for high coercivity grades.
Nd-Fe-B magnets are more prone to oxidation than any other magnet
alloys. If Nd-Fe-B magnet is to be exposed to humidity, chemically
aggressive media such as acids, alkaline solutions salts and
harmful gases, coating is recommended. It is not recommended
in a hydrogen atmosphere.
Neodymium magnets are a member of the Rare Earth magnet family
and are the most powerful permanent magnets in the world. They
are also referred to as NdFeB magnets, or NIB, because they
are composed mainly of Neodymium (Nd), Iron (Fe) and Boron (B).
3 What can Neodymium magnets do? Magnets
affect electrically charged particles and electrical conductors.
Magnets have the ability transform electrical energy without
losing their own energy. These effects can perform useful functions,
for example:
Electrical-to-mechanical effects are key in the function of
motors, loudspeakers, and equipment that requires charged particle
deflection.
Mechanical-to-electrical effects are useful in generators, motors
and microphones
Mechanical-to-heat effects facilitate eddy current and hysteresis
torque devices.
Mechanical-to-mechanical affects, Magnetic separators, Sensors.
Other effects of magnets include magneto-resistance and magnetic
resonance.
4 Temperature constraints The
temperature coefficient of neodymium has triggered several grades
to be developed to meet specific operating requirements. Please
refer to our chart of magnetic properties to compare the characteristics
of each grade. Before choosing a neodymium magnet be sure to
consider your application?s maximum operating temperature.
5 Magnetization Neodymium magnets
require extremely high magnetizing fields and particular consideration
must be given to this when designing complex assemblies. Neodymium
can be magnetized in any direction as long as it is aligned
properly. In some instances multiple pole magnetization is not
possible; when it is possible, special fixtures are required.
6 Are there any regulations for shipping
magnetized materials? According to the United States
Department of Transportation and the Office of Hazardous Materials
Safety, it is against regulations to ship a magnet by air that
maintains a field of more than 0.00525 gauss measured at 4.5
meters (15 feet) from any surface of the package. This is to
prevent the magnet from interfering with the operation of the
aircraft's navigational compass. There are no federal regulations
that restrict the shipping of magnetized materials by ground
transportation. Please check with your commercial carrier for
additional specifics.
7 What materials can be used for magnetic
shielding?
In
general, magnetic field attenuation is a function of the permeability
of the material. A better shielding material has high permeability
per weight. For metallic foil and sheet, the most efficient
shielding material is the 80 Nickel family (e.g., Molypermalloy),
followed by the 50 Nickel alloys (e.g., Deltamax). The economical
silicon-steel foils and sheets are also good shielding material
when weight is not of a major issue.
8 How long do magnets hold their magnetic
strength? If the magnets are not subjected to external
magnetic fields high enough to cause demagnetization - and/or
- elevated temperatures above the advertised maximum use temperature
the field will remain at or near as received. This could be
expected last for the life of the application.
9 Can magnets be made stronger? Once
a magnet is fully magnetized, it cannot be made any stronger.
10 Can magnets that have lost their magnetism
be re-magnetized? That depends on how the magnetism
was lost. Usually magnets can regain their original strength
unless theyve been exposed to extreme heat.
11 Do magnets get weaker? How? Several
factors can weaken the magnetism in a magnet. If a magnet is
stored close to heat, strong electrical currents, other magnets,
or radiation, it can lose its strength. Additionally, high humidity
can corrode neodymium magnets. Demagnetization
Rare Earth magnets have a high resistance to demagnetization,
unlike most other types of magnets. They will not lose their
magnetization around other magnets or if dropped. They will
however, begin to lose strength if they are heated above their
maximum operating temperature, which is 176F (80 C) for standard
N grades. They will completely lose their magnetization if heated
above their Curie temperature, which is 310F (590 C) for standard
N grades. Some of our magnets are of high temperature material,
which can withstand higher temperatures without losing strength.
12 What are magnetic poles? All
magnets have points, or poles, where their magnetic strength
is concentrated. Those points are called poles. We label them
north and south because suspended magnets orient along north-south
planes. On different magnets, like poles repel each other, opposite
poles attract. Are permanent magnets really permanent?
13 What does 'orientation direction' mean? Some
magnets, called oriented or anisotropic magnets, have a preferred
direction in which they should be magnetized. The "orientation
direction," also known as an "easy axis" or "axis,"
is the direction that achieves its maximum magnetism. Other
magnets, called unoriented or isotropic magnets, can be magnetized
in any direction.
14 What are rare earth magnets? The
term Rare Earth Magnets is used to refer to a group of magnetic
materials whose alloys consist of one or more of the Rare Earth
elements. These materials are characterized by exceptionally
strong magnetic properties.
15 Coatings of Neodymium magnets The
coatings do not affect the magnetic strength or performance
of the magnet.
Neodymium magnets are a composition of mostly Neodymium, Iron
and Boron. If left exposed to the elements, the iron in the
magnet will rust. To protect the magnet from corrosion and to
strengthen the brittle magnet material, it is usually preferable
for the magnet to be coated. There are a variety of options
for coatings, but nickel is the most common and usually preferred.
Our nickel plated magnets are actually triple plated with layers
of nickel, copper, and nickel again. This triple coating makes
our magnets much more durable than the more common single nickel
plated magnets. Some other options for coating are zinc, tin,
copper, epoxy, silver and gold. Our gold plated magnets are
actually quadruple plated with nickel, copper, nickel and a
top coating of gold.
16 Grades of Neodymium magnets
N35, N38, N42, N45, N48, N50, N38SH...what does it all mean? Neodymium
magnets are all graded by the material they are made of. As
a very general rule, the higher the grade (the number following
the 'N'), the stronger the magnet. The highest grade of neodymium
magnet currently available is N50. Any letter following the
grade refers to the temperature rating of the magnet. If there
are no letters following the grade, then the magnet is standard
temperature neodymium. The temperature ratings are standard
(no designation) - M - H - SH - UH - EH. You find the temperature
rating of each grade on our Specifications of Neodymium Magnets
Page.
The grade, or "N rating" of the magnet refers to the
Maximum Energy Product of the material that the magnet is made
from. It refers to the maximum strength that the material can
be magnetized to. The grade of neodymium magnets is generally
measured in units millions of Gauss Oersted (MGOe). A magnet
of grade N38 has a Maximum Energy Product of 38 MGOe. Generally
speaking, the higher the grade, the stronger the magnet.
17 Rare earth magnets There are
two types of rare earth magnets available: Neodymium and Samarium
Cobalt.
They are called rare earth because their composition elements
found in the "Rare Earth" or Lanthanides portion of
the Periodic Table of Elements.
Neodymium magnets (Nd-Fe-B) are composed of neodymium, iron,
boron and a few transition metals. Samarium cobalt magnets (SmCo)
are composed of samarium, cobalt and iron. These rare earth
magnets are extremely strong for their small size, metallic
in appearance and found in simple shapes such as rings, blocks
and discs.
Due to their tremendously high energy level, Rare Earth magnet
material is ideal for miniaturized applications. They offer
high resistance to demagnetization and are recommended for applications
with temperature ranges under 200oF. Raw Rare Earth magnets
have a dull metallic appearance and tend to be very brittle.
They can be ground, but caution must be exercised not to crush
the material. Be aware of possible fire from the dust particles
produced from grinding or cutting Rare Earth magnet materials.
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