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The
Alnico
(Aluminum,
Nickel,
Cobalt)
family
was
introduced
in the
1930's.
AlNICo
magnets
derive
their
magnetic
properties
and
their
name
from
their
main
constituents
-
aluminum,
nickel,
and
cobalt.
They
have the
widest
range of
temperature
stability
of any
standard
magnetic
material,
It's
characterized
by
excellent
temperature
stability,
high
residual
induction,
and
relatively
high
energies.
These
were the
first
materials
specifically
designed
for
permanent
magnets
to be
used in
meters
and
instruments
commercially.
As
one of
the
oldest
members
of our
magnet
family,
Alnico
remains
the
workhorse
of the permanent
magnet
industry
and can
be
relied
upon to
deliver
impressive
flux
density
at an
economical
price.
Alnico
also
boasts
the
lowest
temperature
coefficient
of any
commercial
magnet
material
(0.02%
per
degree
centigrade)
allowing
for
excellent
stability
over a
wide
temperature
range.
The surfaces of cast Alnico magnets are usually dark grey, have wide tolerances, and have a rough finish. Critical dimensions are abrasively cut or ground in order to maintain close tolerances and improve the fit and finish. Sintered magnets usually require minimal grinding because they can be produced with tighter dimensional tolerances. It is usually desirable to have features developed in the casting or sintering operations because conventional machining methods are difficult to employ when fabricating Alnico magnets.
Alnico
is
available
in both
cast, sintered
and
bonded
forms.
Sintered
Alnico
offer
slightly
lower
magnetic
properties
but
better
mechanical
characteristics
than
cast
Alnico.
These
materials
are
brittle,
hard and
cannot
effectively
be
machined
by
conventional
techniques
other
than by
grinding.
Advantages
for
using
Alnico:
Excellent
temperature
characteristics
Capable
of
working
at a
wide
range of
temperature
up to
550
degrees
centigrade.
High
field
strengths
at
medium
prices
Easy of
magnetizing, The
lower
coercive
force of
Alnico
makes
magnetizing
a simple
matter
in most
cases
Compatible
with
most
painting
or
plating
systems
(including
nickel
and
copper)
Charasteristics:
Suitable
for
small
volume
magnet
with
complex
shape;
Compact
crystal,
high
intensity;
Regular
shape,
precision
size;
Even
elements,
stable
performance;
Suitable
for
compound
magnet;
Excellent
temperature
stability
(temp.
coefficient
of Br is
the
smallest
among
all of
the
other
permanent
magnets.)

DESIGN
CONSIDERATIONS
Because
Alnico
magnets
are
coarse-grained,
hard and
brittle,
they
cannot
be
drilled
or
conventionally
machined.
Given
these
mechanical
properties,
Alnico
parts
are not
normally
used as
structural
members.
Where a
choice
exists,
select
simple
shapes.
Slots
are
preferred
over
holes.
Cross
sections
of less
than
0.125"
(3.18
mm)
should
be
avoided.
Finished
surfaces,
when
required,
may be
produced
by
grinding;
however,
for many
applications,
the "as
cast" or
"as
sintered"
surface
yields a
satisfactory
result
at a
significantly
lower
cost. To
facilitate
mounting
and give
adequate
protection
to the
magnet,
special
assemblies
such as
rotors
and
magnetron
magnets
may be
supplied
with an
aluminum
jacket.
Additionally,
low
carbon
steel
pole
pieces
may be
attached
to
magnet
pole
faces by
adhesive
bonding
or with
studs or
bolts.
Plastisol
or paint
can be
applied
for
improved
appearance
Application:
Commercially
viable
Alnico
magnets
have
been in
production
since
the mid
1940s.
Many
applications
that
originally
utilized
Alnico
have
switched
to
Ceramic
or Rare
Earth
magnets.
Most new
applications
do not
employ
alnico
alloy
unless
the
magnets
are
exposed
to high
heat or
corrosive
environments.
Alnico
magnets
are used
extensively
in
aerospace
applications,
automotive,
consumer
goods,
and
medical
devices.
Main
applications
are:
Inner
magnetic
voltmeter/ammeter,
electronic
type
power
energy
measuring
instrument, avometer, flowmeter;
A wide
range of
magnetic
sensor,
polarized
relay
,temperature
and
pressure
controller;
Buzzer
of
Mobile
phone,
hearing
aids,
mini
speaker;
lighter
of
automobile,
odometer
of
automobile
and
motorcycle,
permanent
motor,
adsorptive
appliance;
Alnico
has
experienced
renewed
interest
in
recent
years in
such
temperature-sensitive
applications
as
hall-effect
and MR-based
automotive
and
electronic
sensors,
in
addition
to the
traditional
magnetron,
TWT
amplifiers,
actuators,
motors
and
instruments
applications
that
have
long
relied
upon
Alnico.
AlNiCo
magnets
Excellent
temperature
stability,
high
residual
induction,
and
relatively
high
energies
characterize
Alnico
materials,
composed
primarily
of
alloys
of
Aluminum,
Nickel,
and
Cobalt.
They are
manufactured
through
either a
casting
or
sintering
process.
AlNiCo
(Aluminum-Nickel-Cobalt)
Magnet
is
high-energy
permanent
magnet,
which
posses
high
flux
density,
high
coercive,
high
energy
product
and
extreme
stability
for
temperature
changes.
It
exhibits
good
resistance
to
demagnetization,
stability
in high
temperatures
and
excellent
conduction |