cast alnico

Transcription

cast alnico

Permanent Magnets Catalogue
ALNICO
RARE EARTH
FERRITE
FLEXIBLE
ASSEMBLIES
Certificate Number FM 31278
www.eclipse-magnetics.co.uk
CONTENTS
Introduction
3
Materials & Technical Information
4/7
The Product Range - A selection of Cast Alnico Magnets
Cast Alnico
8
Horseshoe Magnets & Related Types
9/10
Button Magnets & Deep & Shallow Pot Magnets
11/12/13
Rotor Magnets
14
Cylindrical & Ring Magnets
15/16
Rectangular & Cylindrical Bar Magnets
17/18
The Product range - A selection of Ferrite Magnets
Ferrite
19
Disc, Bar and Rectangular Block Magnets
20
Assemblies
21
The Product range - A selection of Rare Earth Magnets
Neodymium Iron Boron
22
Pot, Bar, Block and Ring Magnets
22
The Product range - A selection of Flexible Bonded Materials
Magnetic Sheet
23
Magnetic Strip
24
Standard Sizes
25
More Useful Information
Specification Requirements for Enquiries
26
Magnet Care Information
27
Glossary
28
02
Introduction
Eclipse Magnetics Ltd has been at the forefront of magnetic product design and manufacture for over 80 years. Based in Sheffield,
England, the capability of the company and the quality of its
products became apparent when the British Government
approached the company to undertake the manufacture of
permanent magnets for magnetos during the early years of the First
World War.
Today, Eclipse Magnetics has an enviable reputation for designing
world beating magnetic products that utilise the least magnetic
material and yet unleash the highest possible performance. They
produce a wide range of magnetically orientated products, spanning cast Alnico bars and standard shapes such as horseshoes,
through to specialised cast magnets and magnetic assemblies for
countless applications. These products are available in a variety of
magnetic materials - the company produces Cast Alnico magnets
and can offer a comprehensive range of Ferrite and Rare Earth
magnets. These can be of simple design - for example Ferrite rings,
magnetic flexible sheet or more complex Neodymium Iron Boron
magnets for sophisticated applications.
Eclipse Technicians are magnet experts - it’s what they do all day
and every day. They are a dedicated and highly trained team and
are able to provide invaluable technical advice on magnet use and
applications, as well as guiding customers on the best magnet
material and construction for the devices they require. Eclipse’s
resources were recently strengthened by the investment in a new
state of the art laboratory. This is capable of the detailed analysis of
all currently available magnetic materials and those currently being
developed for the future.
The Eclipse brand is internationally renowned for high levels of
quality and performance. The company’s dedication to this standard is reflected in the accreditation of the internationally recognised ISO Quality Award.
Whatever the magnetic problem, wherever the location, consult us
at the ‘drawing-board’ stage whenever permanent magnets are
concerned and let an Eclipse Technician propose an
effective solution.
Over 80 years of magnetic experience ...... yours free with every
magnet purchased.
03
TECHNICAL INFORMATION
Permanent Magnet Materials
The principal materials in which permanent magnets are supplied are shown on the accompanying family of
curves and tables. They are of the following main types.
Al-Ni-Co-Fe (Alnico)
ALCOMAX, HYCOMAX, ALNICO and ALNI are in this class.
Alcomax, available with three different balances of
properties, and Hycomax, a variety of Alcomax with lower
remanence but exceptionally high coercivity, are anisotropic
materials. Anisotropy is developed along one particular axis
at the expense of other axes by exposure to a magnetic
field during heat treatment. The stored magnetic energy,
when magnetised along the preferred axis, is about three
times as great as is possible with Alnico. The curves and
figures relate only to the preferred axis.
The additions increase the intrinsic coercive force which not
only enables a higher working temperature to be achieved,
but make these grades more suitable for DC motor
applications.
Due to their method of manufacture NdFeB magnets are
very brittle and great care must be taken when handling
them.
Please note that all grades should be coated if they are to
be used in a harsh environment, due to their poor resistance to corrosion. All are anisotropic.
See page 22 for further details of our range.
Alnico, an earlier material not having directional properties,
is largely superseded by the anisotropic materials. It is,
however, still used for shapes of magnets unsuitable for
anisotropic materials, such as multi-pole rotor magnets and
older types where re-design is not justified.
These materials have exceptionally good temperature
change and high temperature characteristics, and are ideal
for temperatures up to 550ºC
Ferrite
FEROBA III is a pressed and fired stronium ferrite and is a
ceramic material.
Samarium Cobalt (Rare Earth Cobalt)
Sintered Samarium Cobalt magnets are produced by a
powder metallurgy process and the most of the magnets
supplied are cut from isostatically pressed blocks.
Both the 1:5 and 2:17 grades provide substantially higher
flux densities than either Alnico or Hard Ferrite. This extra
performance enables a considerable reduction in magnet
size and so miniaturisation of systems is possible. To
optimise the use of Rare Earth Cobalt magnets a complete
redesign is required to maximise the advantages of these
magnets. The magnets, however, are extremely brittle and
should be handled with great care, especially when in a
magnetised condition. They also benefit from a maximum
operating temperature of 250-300ºC.
The maximum operating temperature of ferrite is much
lower than alnico material. Magnets in FEROBA III are
normally supplied in the magnetised state.
Ferrite magnets are immune to magnetic damage with
ordinary handling. They also benefit from a high corrosion
resistance
Neodymium Iron Boron (NdFeB)
Sintered Neodymium Iron Boron magnets are produced by
a powder metallurgy process and represent the highest
performance magnets commercially available. However,
they do have a temperature limitation, in that for the highest
performance material, they have a maximum operating
temperature of around 100ºC. It is for this reason that there
is a wide range of grades, mostly with alloy additions to
increase the maximum working temperatures, but at the
expense of a reduction in the BHmax.
04
Magnetic Sheet and Related Products
Flexible Bonded Magnetic Sheet consists of a fine magnetic powder (Barium Ferrite) loaded into a flexible thermoplastic binder. The compound is then calendered into sheet and
magnetised. Self-adhesive or coloured vinyls are added to
the non-magnetic face as required. Extruded profiles are
also available to customers own drawings
Bonded Magnetic Sheet is exceptionally flexible and will
remain so over a wide range of normal atmosphere
temperatures. As with most synthetic materials it is
somewhat temperature dependent.
Typical Magnetic Performance Range - Cast Alnico
Remanence
Coercivity
Maximum energy
product
Br
Tesla
Hc
(gauss)
ALNI
KA/m
(oersted)
(BH)
Kj/m3
Max Mgo
USA
German
equiv.
equiv.
6000
0.6
470
37.3
1.2
9.6
Alnico 1
Alnico 120
ALNICO
7900
0.8
490
38.9
1.7
13.1
Alnico 2
Alnico 160
Alcomax 2
12800
1.3
590
47.0
5.0
39.8
Alnico 5C
Alnico 500
Alcomax 3
12300
1.2
635
50.5
5.2
41.4
Alnico 5
Alnico 500
Alcomax 4
11250
1.1
725
57.5
4.3
33.8
Alnico 6
Alnico 400
Alcomax 3 semi-columnar
13100
1.3
700
55.7
5.8
46.2
Alnico 5DG Alnico 600
Columax
13100
1.3
720
57.3
6.8
56.7
Alnico 5-7
Alnico 700
Hycomax 2
8250
0.8
1125
89.3
3.8
29.8
Alnico 8
Alnico 450
Hycomax 3
8500
0.9
1475
117.4
4.9
39.0
Alnico 8
Alnico 450
Hycomax 3HE
8500
0.9
1550
123.4
5.4
43.0
Alnico 8HE
Alnico 450
15% Cobalt Steel
8200
0.8
176
14.0
0.6
4.9
35% Cobalt Steel
9000
0.9
251
20.0
1.0
7.5
TYPICAL DEMAGNETISATION CURVES FOR CAST ALNICO
Material Grade/Specification - Nominal Chemical Composition
Al
Ni
Co
Cu
Ti
Si
S
Nb
Fe
USA equiv.
German equiv.
ALNI
13.0
26.0
0.5
4.0
-
-
0.2
-
BAL
Alnico 1
Alnico 120
ALNICO
9.8
19.0
12.0
6.0
0.5
-
0.2
-
BAL
Alnico 2
Alnico 160
Alcomax 2
8.1
12.0
23.0
4.5
0.5
0.3
0.2
-
BAL
Alnico 5C
Alnico 500
Alcomax 3
8.3
13.5
24.5
3.0
-
0.3
0.2
0.5
BAL
Alnico 5
Alnico 500
Alcomax 4
7.8
14.5
25.0
3.0
0.5
0.3
0.2
1.7
BAL
Alnico 6
Alnico 400
Alcomax 3 - Semi-columnar
8.3
13.5
24.5
3.0
-
0.3
0.2
0.5
BAL
Alnico 5DG Alnico 600
Columax
8.3
13.5
24.5
3.0
-
0.3
0.2
0.5
BAL
Alnico 5-7
Alnico 700
Hycomax 2
7.4
14.5
31.0
3.0
4.0
0.1
0.2
2.0
BAL
Alnico 8
Alnico 450
Hycomax 3
7.0
14.6
35.1
3.1
6.1
0.1
0.2
-
BAL
Alnico 8
Alnico 450
Hycomax 3HE
7.0
13.2
38.0
3.0
6.3
0.1
0.2
-
BAL
Alnico 8HE Alnico 450
15% Cobalt
CO
Cr
W
C
Mo
Fe
Steel
15.0
9.7
-
1.0
1.4
BAL
35.0
5.1
5.1
0.9
-
BAL
35% Cobalt
Steel
Dimensions not otherwise marked are mm. Where inch (“) dimensions are given, mm values are conversions.
Please note that non-standard sizes are also available on request
05
Typical Magnetic Performance Range - Strontium Ferrite
Intrinsic Hc
Jhc
bHc
Grade
Tesla
Gauss
kA/m
Oersted
kA/m
Sintered
GRADE
1
0.22
2200
136
1700
220
2750
8
Sintered
GRADE
2
0.4
4000
160
2000
185
2300
Sintered
GRADE
3
0.37
3700
240
3000
360
3250
Ferrite
Material
Strontium
Magnetising
Force (Min)
BH Max
Strontium
Ferrite
Strontium Ferrite
Br
Oersted kJ/m3 MGOe
Mean
Max
Reversible Curie
Density Working
Temp
Temp
Temp
Coefficient
kA/m
Oersted
gms/cc
ºC
%/ºC
ºC
1
600
7500
4.8
250
-0.19
450
28
3.5
800
10000
5
250
-0.19
450
26
3.3
800
10000
4.9
250
-0.19
450
Typical Magnetic Performance Range - Rare Earth
TYPICAL DEMAGNETISATION CURVES FOR
SAMARIUM COBALT MAGNETS
NEODYMIUM-IRON-BORON
HYCOMAX 3 CURVE SHOWN FOR COMPARISON
(a) BONDED NEODYMIUM IRON BORON
(b) BONDED SAMARIUM COBALT MAGNETS
FEROBA 2 CURVE SHOWN FOR COMPARISON
06
Typical Magnetic Performance Range - Rare Earth
bHc
Intrinsic Hc Jhc
BH Max
Magnetising
Force (Min)
Density
Max
Working
Temp
Mean
Reversible
Temp
Coefficient
Curie
Temp
Grade
Tesla
Gauss
kA/m
Oersted
kA/m
Oersted
kJ/m3
MGOe
kA/m
Oersted
gms/cc
ºC
%/ºC
ºC
Sintered
SmCo
1:5
0.88
8800
630
7800
1500
18750
150
19
2000
25000
8.3
250
-0.04
720
Sintered
SmCo
2:17
1.06
10600
675
8400
1175
14500
200
25
3500
43750
8.4
300
-0.03
800
Bonded
SmCo
0.58
5800
380
4750
720
9000
56
7
2400
30000
5.1
100
-0.04
-
Bonded
N10
0.68
6800
460
5780
820
10300
80
10
3000
37500
6.0
120
-0.16
-
Sintered
N27
1.10
11000
765
9500
900
11250
210
26
2500
30000
7.4
100
-0.12
310
Sintered
N27SH
1.04
10400
850
10500
>1600
>20000
210
26
2500
30000
7.4
<150
-0.12
310
Sintered
N30
1.16
11600
800
10300
880
>11000
230
29
2500
30000
7.4
100
-0.12
310
Sintered
N30H
1.10
11000
800
10300
>1350
>17000
230
29
2500
30000
7.4
100
-0.12
310
Sintered
N33
1.16
11600
850
10700
>900
>11500
255
32
2500
30000
7.4
100
-0.12
310
Sintered
N33H
1.16
11600
850
10700
>1353
>17000
255
32
2500
30000
7.4
100
-0.12
310
Sintered
N35
1.20
12000
850
10700
960
12000
280
35
2500
30000
7.4
100
-0.12
310
Sintered
N35H
1.20
12000
850
10700
>1353
>17000
280
35
2500
30000
7.4
100
-0.12
310
Sintered
N38
1.24
12400
890
11100
955
12000
295
37
2500
30000
7.4
100
-0.12
310
Sintered
N38H
1.24
12400
890
11100
>1353
>17000
295
37
2500
30000
7.4
100
-0.12
310
Iron Boron
Boron
Neodymium Iron
Material
Samarium Cobalt
Cobalt
Br
07
CAST ALNICO
Cast Alnico Magnets
Definitions
• Using patterns and simple moulding techniques, Alnico magnets can be cast to form a vast range of
complex shapes and sizes at an economical cost
Eclipse
Magnetics Alnico magnets are ideal for high temperature applications up to 550ºC
•
Alnico
is
very stable, has good corrosion resistance and a typical hardness of 50 Rockwell C. Once cast,
• the material
is so hard that the only machining possible is grinding
Alnico represents the most versatile magnet material available. The range of properties can be
• Cast
accurately designed for specific applications by changes to element analysis and heat treatment
Typical applications
• ABS braking system magnets
• Reed switch operating magnets
• Electricity meter damping magnets
• Holding/clamping applications
• Microwave applications
• Weighing scale damping magnets
• Electropermanent systems
• Calibration magnets
• Heat treatment jigs and fixtures
Eclipse Magnetics are continually improving their capability to
extend the range from traditional Alnico magnets
Eclipse Magnetics on site casting foundry
08
CAST ALNICO
Horseshoe Magnets and Related Types
Effects of high temperature
It can be stated categorically that there is no finer
material than Alcomax for service at high temperatures.
Further, as all these magnets are one-piece there are
no adverse effects such as differential expansion and
contraction. The benefits of their fine high temperature
performances are therefore available in full.
Definition
One-piece magnets with both poles in the same plane.
The tables list standard varieties of horseshoe
magnets, bridge magnets and channel magnets.
Summarizing, the magnets are not harmed up to
550ºC and can be used at still higher temperatures if
deterioration is acceptable. Up to 400ºC the negative
temperature coefficient is of the order of 0.02% per ºC.
Dimensions
Finish
Only the leading dimensions are quoted in the tables,
without detail and tolerances. Further information will
be provided on request.
Pole faces ground; elsewhere either natural finish or
painted.
Scope
Magnetic State
Most of the types listed are supplied as-cast except
that the pole faces are ground.
Supplied demagnetized or magnetized as required, In
the latter case either in pairs mutually ‘keepering’ one
another or with individual keepers.
Performances
Warning
Indicated on Pull Gap Curves of Magnetic Attraction,
which can be provided for many of the designs.
Some types have grip and depth of field so high as to
be dangerous in trapping fingers. Great care is
necessary to avoid injury.
Materials
In various grades of Alcomax and Alnico, as stated in
the tables. Ax = Alcomax, Ao = Alnico. For
characteristic properties of the materials see pages 05.
Conventional Horseshoes with converging poles
Drg. No.
M 2904
M 14672
M 4181A
Material
Weight (g)
Pull (kg)
28.6
22.2
25.4
7.9
6.4
A=Alnico
28.1
2.4
1.13”
0.88”
1.00”
0.31”
0.25”
D=AxIII
Ax III
25
3.0
Alnico
91
4.0
27.0
18.5
28.5
8.0
11.0
1.06”
0.73”
1.13”
0.32”
0.43”
33.3
27.0
35.0
15.9
7.9
1.31”
1.06”
1.38
0.63”
0.31”
For magnets similar to M 2904A but with a hole through the crown, see BUTTON MAGNETS on page 02
Bridge Magnets
Drg. No.
M 4144
Material
22.2
0.88”
11.1
0.44”
7.9
0.31”
6.4
0.25”
A=Alnico
Weight (g)
Pull (kg)
13
0.9
{ C=AxIV
09
CAST ALNICO
Horseshoes with parallel poles and rounded back
Drg. No.
M 15306
M 16694
M 17022
Material
127.0
98.4
47.6
63.5
5.0”
3.88”
1.88”
2.50”
76.0
63.5
24.0
38.0
3.00”
2.50”
0.94”
1.50”
55.5
46.0
24.0
30.0
2.19”
1.81”
0.94”
1.19”
Weight (g)
Notes
Ax III
2650
Ax III
472
Hole 0.25”
Ax III
228
Hole 0.25”
diameter
diameter
Large Vee-shaped Magnets (diverging poles)
Drg. No.
M 3574/1C
Material
113.0
81.0
124.0
62.5
4.46”
3.18”
4.88”
2.46”
Ax II
Weight (kg)
4.53
Square Horseshoes
Drg. No.
M 6770 A
M 6770 B
M 6770 C
M 5750
M 10208
M 10209
M 10210
Material
30.0
20.0
20.0
15.0
1.18”
0.79”
0.79”
0.59”
40.0
25.0
25.0
20.0
1.57”
1.00”
1.00”
0.79”
45.0
30.0
30.0
23.0
1.77”
1.18”
1.18”
0.90”
60.0
40.0
62.0
31.8
2.36”
1.57”
2.44”
1.25”
57.0
35.0
44.5
27.8
2.25”
1.38”
1.75”
1.09”
70.0
41.0
57.0
34.0
2.76”
1.61”
2.25”
1.34”
79.0
54.0
82.5
38.0
3.11”
2.13”
3.25”
1.50”
Ax II
Weight (g)
Pull (kg)
55
4.5
Notes
Hole 4mm
clearance
Ax II
120
9.0
Hole 5mm
clearance
Ax II
182
11.8
Hole 5mm
clearance
Ax III
652
35.0
Ax III
368
23.5
Ax III
709
37.0
Ax III
1446
47.0
No Hole
}
2 holes
for bolts
Channel Magnets
Drg. No.
Material
M 9113
M 19276
M 19278
M 19281
22.2
22.2
0.88”
0.88”
{
{
A=140.0
Weight (g)
A=426
B=108.0
10.3
A=5.51”
0.41”
Ax IV
B=335
Ax III
93
Ax III
132
Ax III
820
B=4.25”
12.7
7.9
127.0
4.7
0.50”
0.31”
5.00”
0.19”
19.0
12.7
152.0
6.35
0.75”
0.50”
5.98”
0.25”
38.1
22.2
152.0
12.7
1.50”
0.88”
5.98”
0.50”
10
CAST ALNICO
Button Magnets
Effects of high temperatures
As these magnets are one-piece, there are no adverse
effects such as differential expansion and contraction.
The benefits of the high temperature performance of
Alnico are therefore available in full.
Definition
Magnets of cylindrical shape but of ‘horseshoe’ type,
with both poles in the same plane at one end of the
cylinder. There is a groove between the poles, and a
hole through the crown, unless otherwise stated.
Dimensions
Only the leading dimensions are quoted in the tables,
without detail and tolerances. Further information will
be provided on request.
Most of the types listed are supplied as-cast except
that the pole faces are ground.
Summarising, the magnets are not seriously affected
magnetically up to 550ºC. If the magnets are used at
higher temperatures than 550ºC deterioration will take
place over time. Up to 200ºC the negative temperature
coefficient is of the order of 0.02% per ºC.
Finish
Button magnets are ground on the pole faces and the
crown. They are supplied either natural finish or painted.
Magnetic state
Supplied demagnetised or magnetised as required. The
magnets are supplied either in pairs mutually ‘keepering’ one another or with individual keepers.
Special note
Performances
Indicated on Pull Gap Curves of Magnetic Attraction.
Material
Distinguish carefully between Pot Magnets and Button
Magnets as both are cylindrical. The overall dimensions
are similar, but they are entirely different in principle and
performance.
Alnico, unless otherwise stated. For characteristic
properties, see pages 05.
Button Magnets
Drg. No.
M 4776A
12.7
0.50”
0.38”
M 4776B
19.1
12.7
0.75”
0.50”
25.4
1.00”
M 4776C
M 4776D
9.5
4.0
7.0
4.0
0.16”
0.28”
0.16”
5.5
8.7
4.8
0.22”
0.34”
0.19”
15.9
5.5
8.7
4.8
0.63”
0.22”
0.34”
0.19”
31.8
25.4
7.9
12.7
7.1
1.25”
1.00”
0.31”
0.50”
0.28”
Weight (g)
Pull (kg)
6.3
0.7
20
1.9
49
3.4
113
4.8
Notes
Button Magnets with straight slots
Drg. No.
M 4140
M 14331
22.2
19.1
6.4
4.8
0.88”
0.75”
0.25”
0.19”
9.8
6.0
3.7
0.386”
0.250”
0.145”
Weight (g)
Pull (kg)
41
3.0
2.3
No hole
Centreless
Ground
11
CAST ALNICO
Pot Magnets
(e) The magnet proper has the most efficient of all
magnet shapes - a plain cylinder, magnetised
lengthways.
(f) Concentration of magnetic flux in the mild steel,
possibly up to twice the density of the flux in the
permanent magnet. Grip varies as the square of the
flux density, so this is specially advantageous.
(g) Depth of field small compared with that of magnets
with poles farther apart (such as horseshoes), but
grip in intimate contact vastly superior to that of
non-composite magnets of similar weight.
Definition
A pot magnet comprises a cylindrical permanent
magnet assembled concentrically in a steel pot. The
pot is an essential part of the magnetic circuit,
providing the return path for the flux. The two poles are
concentric, in the same plane, on an end face.
Contact surfaces
Applications
Finish
Pot magnets are among the most efficient of all
magnet designs for gripping. (Other designs are
preferable for lifting and attractive duties across gaps).
Ground all over. Supplied either natural finish or
painted.
Pot magnets are primarily for gripping applications, for
which they are ideal. For the most efficient gripping,
contact should be intimate. Contact surfaces should
be maintained in good condition.
Magnetic material
General features
(a) There is no stray flux as the magnetism is retained
in a closed circuit.
(b) The pot screens the magnet proper from
demagnetising effects.
(c) The pot is readily machinable.
(d) Can be inserted into, or fitted to steel without
adverse effect. (This cannot be done with
unscreened magnets).
Alcomax III - one of the most efficient of all
commercially available materials.
Magnetic state
Normally supplied magnetised, individually each with a
keeper, or (with the exception of Magnetic Holdfasts) in
rows with a keeper at the open end of each row.
Deep Pot Magnets
The proportions combine excellent performance with a
high degree of stability.
Assembly and correct spacing are achieved by means
of a force-fitted aluminium ring.
Caution is necessary at temperatures above about
200ºC because of possible mechanical loosening
through expansion and contraction of the component
parts.
Drg. No.
M 5663 Y
9.5
15.1
8.0
6.4
0.38”
0.59”
0.31”
0.25”
M 5663 Z
12.7
15.9
9.9
8.1
0.50”
0.63”
0.39”
0.32”
M 5663 A
17.5
16.0
13.5
10.0
0.69”
0.63”
0.53”
0.39”
M 5663 B
20.5
19.0
16.0
12.0
0.81”
0.75”
0.63”
0.47”
M 5663 C
27.0
25.0
21.0
15.0
1.06”
0.98”
0.83”
0.59”
M 5663 D
35.0
30.0
27.7
22.9
1.38”
1.18”
1.09”
0.90”
Weight (g)
Pull (kg)
M3
6.4
1.0
M4
12.9
2.0
M6
22.7
2.6
M6
38.7
4.0
M6
85
6.1
M6
184
14.7
12
CAST ALNICO
Shallow Pot Magnets
Designed to satisfy the demand for high grip magnets where height is too
restricted for deep pots. Good grip in intimate contact, but not as stable
as deep pots.
Shallow Pots suffer magnetic damage more easily if two should be
opposed - this is unlikely to happen accidentally. With the exception of
M9067A, assembly is by 3-point staking which minimises mechanical
loosening by expansion and contraction. M9067A can withstand
temperatures of up to 100ºC, whereas M9067B, M9067C and M14659 can
withstand temperatures of up to 550ºC.
Drg. No.
M 9067 A
19.1
7.6
16.3
14.7
M3
0.75”
0.30”
0.64”
0.58”
Csk
M 9067 B
28.6
8.7
23.8
22.2
M4
1.13”
0.34”
0.94”
0.88”
Csk
M 9067 C
M 14659
38.1
10.6
32.8
31.0
M4
1.50”
0.42”
1.29”
1.22”
Csk
60.3
15.9
54.0
52.0
M6
2.38”
0.63”
2.13”
2.05”
Csk
Weight (g)
Pull (kg)
13
3.0
35.5
5.0
79.4
13.0
300
50.0
Notes
Hycomax 2
Magnetic Holdfasts
A mild steel concentrator pole piece gives superior gripping ability. The
grip in intimate contact sometimes necessitates a jacking screw for
detachment from loads. This is supplied as standard.
Assembled by filling the annular gap with epoxy resin.
Temperature limitation: 100ºC.
In M 5866/2 and M6207 plain holes are provided: users can tap to their
preferred screw thread.
Drg. No.
M 11345
44.5
44.5
34.9
26.2
1.75”
1.75”
1.38”
1.03”
M 8062
54.0
49.2
41.2
32.5
2.13”
1.94”
1.62”
1.28”
M 8063
69.9
63.5
53.3
42.9
2.75”
2.50”
2.10”
1.69”
M 5866/2
M 6207
Weight (kg)
Pull (kg)
M8
0.50
20
M8
0.83
40
M8
1.75
88
4.30
183
6.15
214
101.6
74.6
76.2
63.5
8.4mm
4.00”
2.94”
3.00”
2.50”
Plain (3)
100.0SQ
100.0
82.6
69.9
8.4mm
3.93SQ”
3.93”
3.25”
2.75”
Plain (8)
Square
Notes
CUBE
4 holes in top
4 holes in one side
13
CAST ALNICO
Magnetic Foot M 5991/1
A rectangular assembly equivalent in performance to two Deep Pots.
(Type M5663C) Weight: 240g
Rotor Magnets
Definition
These magnets have multiple poles. Each pole alternates
in polarity.
Applications
Rotor magnets are ideal for anisotropic heat treatment.
The cored hole is left as cast so that the rotor may be
fitted to shafts. Typical applications for one-piece rotors
are synchronous motors, dynamos and air turbine
generators.
Magnetisation Service
Eclipse Magnetics Limited provide a magnetisation
service for assemblies incorporating these magnets. It is
generally possible to re-despatch assemblies within one
working day of receipt (unless there are unusual
complications necessitating the provision of special
adaptors).
Notes on the Dimensions and Tolerances
Finish and Tolerances
Supplied with a ground finish. Unless specified, the
tolerance on the length is ±0.1mm/±0.004”. Holes, when
provided, are produced by coring and are to casting
accuracy only. The periphery is unground, being fettled
and shotblasted only except where otherwise indicated.
Apart from lengths, the data in the table is generally
nominal and should be regarded as average. The use of
several significant figures does not imply any smaller
tolerances.
Material
Alcomax III unless otherwise specified.
Magnetisation
To gain the full benefits of these magnets, magnetisation
after assembly is essential. They are tested magnetically
and then normally demagnetised before despatch.
Drg. No.
M 16792
M 16555
M 19077
M 16473
19.0
25.0
6.4
0.75”
0.98”
0.25”
19.0
31.8
6.4
0.75”
1.25”
0.25”
22.4
38.0
9.6
0.88”
1.50”
0.38”
31.8
50.8
12.7
1.25”
2.00”
0.50”
No. of Poles
Material
Weight (g)
4
Ax III
51
6
Ax III
18
6
Ax III
132
8
Ax III
333
14
CAST ALNICO
Cylindrical and Ring Magnets
Definition and scope
Cylindrical magnets with anistropic preferred axis from
one flat pole face to the other. Length and diameter are
similar. Such magnets are sometimes known as
“centrepoles” or “slugs”. Some products in this range
are cone shaped.
being fettled and shotblasted only, except where otherwise indicated.
Material
Alcomax III unless otherwise specified.
Magnetisation
Efficiency
Cylindrical magnets are ideal for anistropic heat
treatment because they are straight and have a
constant cross section area and length. Thus, on the
basis of stored magnetic energy per unit volume they
are more efficient than other designs in the same
materials. Consequently they offer the benefits of
minimum weight, size and cost for many applications.
Application
These magnets are intended for assembly with soft
magnetic components (mild steel is suitable) to form
complete magnetic systems. Typical applications are
loudspeakers, moving coil instruments, pot magnets
(for gripping applications), conveyor rails/pulleys and
jigs for the heat treatment of drills. These magnets are
exceptionally versatile.
To gain the full benefits of these magnets,
magnetisation after assembly is essential. They are
tested magnetically and then normally de-magnetised
before despatch.
Magnetisation service
Eclipse Magnetics Ltd. provide a magnetisation service
for assemblies incorporating these magnets. It is
generally possible to re-despatch assemblies within
one working day of receipt unless there are unusual
complications necessitating provision of
special adaptors.
Notes on the dimensions and tolerances
Apart from lengths, the data in the table is generally
nominal and should be regarded as average. The use
of several significant figures does not imply any smaller
tolerances.
Finish and tolerances
Cylindrical magnets are supplied with a ground finish
on the two flat surfaces. Unless otherwise specified the
tolerance on the length is: ±0.1mm /±0.004”. Holes,
when provided, are produced by coring and are to
casting accuracy only. The periphery is unground,
Solid Cylinders (no hole)
Drg. No.
M 5664Z
M 5664A
8.1
12.5
0.32”
0.49”
10.0
12.9
0.39”
0.51”
M 5664B
12.0
14.7
0.47”
0.58”
M 5992C
15.0
20.9
0.59”
0.82”
M 4705B
M 5664D
M 4649A
M 4649B
M 4649C
21.3
15.9
0.84”
0.63”
23.0
21.8
0.91”
0.86”
25.4
15.9
1.00”
0.63”
27.0
19.1
1.06”
0.75”
29.0
22.2
1.14”
0.88”
Weight (g)
Notes
4.5
Centreless ground
7.7
Centreless ground
13.2
30.4
41.7
67.6
59
80
107
Centreless ground
Dimensions not
otherwise marked are
mm.
Where inch (“)
dimensions are given,
mm values are
conversions.
15
CAST ALNICO
Tapered Cylindrical Cones
Drg. No.
M 11068
50.8
44.5
44.5
15.9
2.00”
1.75”
1.75”
0.63”
Plain Cylinders with Central Fixing Hole
Drg. No.
M 4075/1
M 3012/2
M 4075/2
M 4075/3
M 4075/4
M 4075/5
M 4075/6
M 14639
Weight (g)
26.2
7.9
15.9
1.03”
0.31”
0.63”
27.0
6.0
22.9
1.06”
0.24”
0.90”
27.8
7.9
19.1
1.09”
0.31”
0.75”
29.7
7.9
22.2
1.17”
0.31”
0.88”
32.5
8.7
25.4
1.28”
0.34”
1.00”
34.9
9.5
28.6
1.38”
0.38”
1.13”
37.3
9.5
31.8
1.47”
0.38”
1.25”
52.0
7.5
13.0
2.05”
0.30”
0.51”
Notes
57
Hole clears 6mm bolt
91
78
105
144
185
238
198
Csk one end
Mod Hyc.
Ring Magnets
Anistropic preferred axis from one flat face to the other unless otherwise stated.
Pole faces are ground. Otherwise ground as cast and fettled only.
Drg. No.
M 14801
M 14802
16
Material
31.7
25.4
27.0
1.25”
1.00”
1.06”
61.0
50.0
27.0
2.40”
1.97”
1.06”
Ax III
Ax III
CAST ALNICO
Rectangular Bar Magnets
Materials
Alnico (Ao) and various grades of Alcomax (Ax).
Effects of high temperatures
Safe working limit 550ºC. Can be used up to 700ºC in
certain circumstances: see page 22. Can be
incorporated into die castings.
Finish
One-piece magnets of high length/cross section ratio
with two poles situated at opposite ends.
As cast and fettled only except on pole faces (ends)
which are finish ground, unless otherwise specified.
Supplied either natural finish or painted. Long
cylindrical bars can be supplied unground to enable
customers to grind and cut up the bars into individual
magnets.
Scope
Magnetic state
Cast cylindrical and rectangular bar magnets available
as standard sizes and cut to length pieces.
Demagnetised or magnetised in pairs or rows.
Definition
Rectangular Bar Magnets
Cross
Maximum
Length
¦
Drg. No.
Normal
Material
Section
M 8894/2A
Ax III
5 x 10
20
M
Pull (kg)
0.6
North Pole identified
Notes
M 8894/2B
Ax III
5 x 12.5
40
1.5
M 8894/2C
Ax III
5 x 15
60
2.2
M 4985/2
Ao
10 x 15
50
1.9
M 4984/2
Ao
10 x 15
75
1.9
M 18978
Ao
6 x 12
75
1.8
North pole identified
M 19690
Ao
6 x 12
50
1.8
M 19691
Ao
6 x 12
100
1.8
M 19087
Ax III
4”
0.8
M 19088
Ax III
1/8” x 3/8”
3/16” x 3/8”
4”
0.8
M 19089
Ax III
1/2”
4”
0.8
1/2”
6”
2.7
M 19090
Ax III
1/8” x
1/2” x
It is not usual to plot pull gap curves for bar magnets
since bar magnets do not satisfy the basic condition
for ideal gripping and pulling that both poles should be
in the same plane.
Fiqures shown are only to be used as a performance
guide.
17
CAST ALNICO
Cylindrical Bar Magnets
Individual Sand Cast Cylindrical Bar Magnets
• Bar Size: 6 - 20mm diameters
• Cast tolerance: ±0.3mm diameter, 250mm length. Can be supplied as
cut pieces to ±0.2mm. Vacuum and sand cast bars can be ground on
diameter to 0.5mm
Diameter
Material
Minimum
Length
¦
Normal
Drg. No.
M
Pull (kg)
Notes
M 8731/1A
Ax III
6.0
20
0.6
M 8731/1B
Ax III
8.0
25
0.9
Cast
M 8731/1C
Ax III
10.0
30
1.5
Cast
Ao
12.7
52
M 4246B
Cast
Centreless ground
Vacuum Cast Cylindrical Bar Magnets
• Cast in long sticks and can be ground on
diameter (±0.025mm) then cut up into short
magnets (to ±0.2mm)
• Bar Size: 3 - 10mm diameter
• Cast tolerance: ±0.3mm diameter, 100 to
250mm length, minimal, dependant upon the
diameters
Cutting Facilities
Magnacut, a division of eclipse Magnetics are specialists in the processing of all types of magnets, with
special abilities for cutting alloys in volume.
18
FERRITE
Ferrite Magnets
Key Features
Bonded and Sintered Ferrites are made up of metal
oxides. They are known as ceramic magnets because
of their physical properties which are comparable to
porcelain (hard and brittle).
The maximum operating temperature is lower than
Cast Alnico material at 250ºC.
Of all magnet materials, Ferrite magnets are the most
widely used throughout the world because they
combine low cost manufacture with high coercive
properties.
Sintered Ferrite
Sintered Ferrites are produced from Stronium and have
anisotropic properties. The magnets are usually formed
by wet pressing.
Bonded Ferrite
Formed by mixing ferrite powders with polymer based
resins which makes it ideally suitable for low cost
applications. This product is often used for a wide
range of electronic and small motors used in the
automotive industry.
(a) SINTERED FERRITE MAGNETS
(b) BONDED FERRITE MAGNETS
Typical Applications
Ferrite (Sintered)
• Audio/television applications
• Holding/clamping applications
• Loud speaker units
• Reed switches
• Security systems
• Sump plugs
• Water conditioners
Ferrite (Bonded)
• Instrumentation (Automotive applications)
• Reed switches
• Sensor applications
See pages 06 for technical information.
19
FERRITE
Sintered Ferrite Magnets
Definition
Magnets are produced by either dry or wet
pressing followed by sintering stronium and
barium carbonates.
Feroba I - Isotropic multipole
Feroba II and II - Anisotropic
Temperature
250ºC maximum
Magnetisation
Disc Magnets
Drg. No.
Diameter
Thickness
M 15321
14
5
Fer I
M 15322
20
5
Fer I
M 15530
25
3
Fer I
M 15531
25
5
Fer I
M 15323
30
5
Fer I
Axial configuration
Material
Standard
Sintered Feroba
Magnetisation
Multipole on
one face
Non-Magnetic face
Multipole configuration
Ring Magnets
Drg. No.
Outside
Inside
Diameter
Diameter
Thickness
Material
Standard
Sintered Feroba
Magnetisation
M 15009
20
5
9
Fer II
M 15224
36
18
8
Fer II
M 15571
39
22.5
8
Fer II
M 15968
45
22
9
Fer II
M 15572
50
25
8
Fer II
M 15131
60
24
8
Fer II
M 15574
70
32
10
Fer II
M 16048
72
47
10
Fer III
M 15575
90
40
13
Fer II
Magnetised through
the thickness
Rectangular Block Magnets
Drg. No.
Width
Thickness
Length
(Axis)
Material
Standard
Sintered Feroba
Magnetisation
M 16027
9
6
49.5
Fer III
M 13704
19
4.8
50
Fer III
M 15065
25
20
60
Fer III
M 15069
32
10
75
Fer III
M 15073
40
15
125
Fer III
M 10792
50
20
75
Fer III
M 16540
100
25
150
Fer III
Magnetised through
the thickness
Note
Individual magnets supplied as cut pieces to customer requirements:
Tolerances up to 25mm ±0.2mm
up to 50mm ±0.5mm
up to 100mm ±0.5mm
Thickness (Axis) ±0.15mm
20
FERRITE ASSEMBLIES
Heavy Duty Ferrite Shallow Pot Magnets
Definition
Heavy Duty Ferrite Shallow Pot Magnets are made from Ceramic Ferrite
material inside a mild steel shell and offer a high clamping force. Supplied
with a central M6 tapped hole and removable jacking screw for ease of
release.
Temperature
80ºC maximum.
Drg. No.
Diameter
Thickness
Pull (kg)
Thread Size
Fixing Stud Centres
M 15562
66
10.7
25
M6
46mm/3holes
PCD (mm)
M 15563
76
12.5
33
M6
46mm/3holes
M 15564
100
15.0
55
M6
63mm/3holes
Ferrite Shallow Pot Magnets
Definition
Ferrite Shallow Pot Magnets offer a high clamping force, even on painted
surfaces and are especially suitable for clamping onto thin sheet metal
surfaces. Supplied with a central M6 tapped hole and a removable hook.
Temperature
80ºC maximum.
Drg. No.
Diameter
Thickness
Pull (kg)
Tread size
M 15559
46
10.7
6
M6
M 15560
56
10.7
16
M6
M 15561
66
10.7
25
M6
Ferrite Shallow Pot Magnets - Zinc Plated
Definition
Ferrite Shallow Pot Magnets are supplied bright Zinc plated and are suitable for attracting, clamping and positioning
applications.
Temperature
80ºC maximum.
Tapped Fixing Hole
Drg. No.
Diameter
Thickness
Pull (kg)
Fixing Hole
M19810/1XK
10
11.5
0.3
M3
M19810/2XK
13
11.5
0.5
M3
M19810/3XK
16
11.5
1
M3
M19810/4XK
20
13
2.5
M3
M19810/5XK
25
15
4
M4
M19810/6XK
32
15
7
M4
M19810/7XK
36
16
8
M4
M19810/8XK
40
18
10
M5
M19810/9XK
47
17
15
M4
Countersunk Screw Drg. No.
All accept 5mm countersunk screw
Diameter
Thickness
Pull (kg)
M19812XR
25
7
4.5
M19835XR
32
7
10
M19813XR
40
8
20
21
NEODYMIUM IRON BORON MAGNETS
Definition
Finish
A single Bi Pole assembly comprising a Neodymium Iron Boron
magnet with pole pieces encased in an aluminium pot.
Pole faces ground. Pot natural aluminium or paint.
Application
Supplied magnetised with keeper or in rows with a keeper at
the open end of each row.
Designed for contact gripping where equal or greater holding
forces can be achieved from a smaller magnet over a
conventional pot magnet.
Magnetic state
Temperature
120˚ C maximum.
Neo-hold Bi-Pole Gripping Magnets
Part Number
M 16382
M 16386
M 16390
M 16394
12.7
16.0
22.0
25.0
11.6
15.6
20.0
25.0
5.5
5.5
5.5
5.5
Fixing hole
M5 x 5
M6 x 5
M6 x 6
M6 x 6
Pull (max Kg)
2.0
5.0
9.0
15.0
Disc, Block and Ring Magnets
RARE EARTH MAGNETS - A SELECTION OF THE STANDARD SIZES AVAILABLE
Finish
Nickel plate unless otherwise stated.
Temperature
Magnetic State
120˚C maximum:
180˚C by special request.
Magnetised
Block Magnets
Part Number
N35A251003
N35A251005
N35A251010
N35A252510
N35A402530
N35A452510
N35A452520
N35A502505
N35A502510
N35A505013
Width Thickness
(Axis)
10
3
10
5
10
10
25
10
25
30
25
10
25
20
25
5
25
10
50
12.5
Length
25
25
25
25
40
45
45
50
50
50
Ring Magnets
Part Number
Outside
Inside
Diameter Diameter
N35A194576
19
4.5
N35A200610
20
6
N35A200610CK 20
6
N35A221802
22
18
N35A230710
23
6.5
N35A230720
23
6.5
N35A341809
34
18
N35A725130
72
51
Length
(Axis)
7.6
10
10
2
10
20
9
30
Disc Magnets
Part Number Diameter
N35A027048
N35H0302
N35A0402
N35A0404
N35A0502
N35A0505
N35A0510
N35A0601
N35A0604
N35A0606
N35A0630
N35A0903
N35A0909
N35A0909
N35A1003
N35A1005
N35A125055
N35A135035
N35A2003
N35A2010
N35A2210
N35A3806
PLEASE NOTE THAT NON-STANDARD SIZES ARE ALSO AVAILABLE ON REQUEST
22
2.7
3
4
4
5
5
5
6
6
6
6
9
9
9
10
10
12.5
13.5
20
20
22
38
Length
(Axis)
4.8
2
2
4
2
5
10
1
4
6
30
3
9
9
3
5
5.5
3.5
3
10
10
6
FLEXIBLE BONDED MAGNETS
Magnetic Sheet
General Information
Colour
Surface Finishes
Plain magnetic material assumes the colour of the
barium Ferrite powder, ie dark brown. Any colour can
be achieve by laminating with the appropriate coloured
material.
Plain products have a smooth clean surface which is
suitable for accepting flexible paints, adhesives or self
adhesive.
Temperature Effects
Total flux of 0.2% per ºC rise, recoverable on cooling.
Flexibility will increase with elevated temperature.
Storage
Adhesive Backed Items are laminated on the
non-magnetic face with a good quality acrylic type
double sided adhesive complete with siliconised
release paper. Colour Faced Sheet is laminated with a
high quality self adhesive PVC film on the
non-magnetic face.
Great care must be taken with storage. Rolls of
material should not be stored on end or on one edge,
otherwise distortion will occur. For preference rolls
should be suspended on the centre core. Vinyl faced
material should be sheeted and stored flat colour face
to colour face.
N
S
Reverse
Non-magnetic
Forms of Magnetisation
Isotropic
Magnetic Stability
Magnetised multipole on one surface with pole pitching
of approx. 3mm. As the poles are closely spaced very
small pieces can be cut with no loss of performance.
By using high coercivity powders the material is immune
to magnetic damage in normal use.
Physical Stability
Anisotropic
The material has good aging resistance and can be used
both indoors and outdoors. However, the coloured vinyl
surface is subject to some fading with prolonged outdoor use.
Magnetised through the thickness. Suitable for magnetic
sandwiches.
Special Shapes
The poles will be either parallel or at right angles to the
roll length.
Machinability
As the material has excellent flexibility and impact
resistance it can be easily cut with scissors or knives.
Regular shapes can be punched using inexpensive dies.
Magnetic Performance
The figures quoted below are the vertical pull achieved
when the sheet is placed in contact with finely ground
mild steel.
Typical figures are :0.5mm thick
23 grams/cm2
0.75mm thick
39 grams/cm2
Normally supplied in roll or sheet form but quantities
permitting special cut shapes such as circles, rectangles,
triangles, etc, can be produced provided customers
contribute to the cost of form cutters.
Special Sizes
Material is available to special order in alternative
widths, thickness and lengths.
*Width
Both the laminated adhesive and vinyls will be a
minimum of 610mm wide. An unsurfaced salvage edge
of magnetic sheet may be apparent.
23
Magnetic Strip
Description
Flexible Bonded Magnetic Strip consists of a fine
magnetic powder (Barium ferrite) loaded into a flexible
thermoplastic binder. The compound is then extruded
to give the required form and finally magnetised with
the appropriate pole arrangement.
Flexibility
The degree of flexibility is dependent on the cross
section of the profile. All strips can be coiled around a
100mm dia. former without damage.
Forms of Magnetism
Magnetic Performance
Magnetic strip is mostly supplied magnetised as in Fig.
2. Thin profiles are magnetised as in Fig. 1 to obtain
maximum gripping performance on working face.
Alternative forms 3, 4 and 5 can be supplied for speFig. 1 cial applications.
Relatively low magnetic pull when compared to metallic magnets. When sandwiched with mild steel to provide flux concentration very high contact grips can be
achieved.
Magnetic pull achieved with 75mm piece of 10596
magnetised as Fig. 3 and combined with mild steel to
form a sandwich.
N
S
N
S
N
Maximum Temperature
Suitable for thin profiles
Maximum recommended operating temperature 80oC
Fig. 2
Methods of Combining with Pole Plates
N
To provide flux concentration, and hence increase the
magnetic pull, strip can be combined with mild steel in
several configurations, eg:
S
Normal for gripping applications
Magnetic pull achieved with standard magnetisation of
strip lifting a ground mild steel block.
Fig. 3
Physical Stability
N
Excellent toughness. Corrosion and weather resistant.
Special Sizes and Profiles
S
Suitable for magnetic sandwiches
Fig. 4
Dies are continually being added to our range and
further ones will always be considered providing
customers agree to contribute to the tooling cost.
Special Cut Lengths
N
Normally supplied in complete coils only, but providing
quantities are sufficiently large cut pieces of 10mm and
above can be supplied.
S
For equal adhesion on both wide faces
Special Finishes
Fig. 5
N
Certain profiles can be supplied with double sided
pressure sensitive adhesive on non-magnetic face.
S
Magnetised along the length of the profile
Max. 40mm
Machinability
Strip can be easily cut, drilled, punched and shaped
without the need for expensive equipment.
24
Special Magnetisation
In certain cases alternative forms of magnetisation can
be provided on standard profiles.
FLEXIBLE BONDED MAGNETS - A SELECTION OF THE STANDARD SIZES AVAILABLE
Description
Performance
Flexible bonded magnetic sheet consists of a fine magnetic
powder (Barium/Strontium ferrite) loaded into a flexible
termoplastic binder. The compound is then calendered
into sheet or extruded into strip
Sheet:
0.5mm thick
0.75mm thick
23gms/cm2
39gms/cm2
Temperature
Plain:
80˚ C maximum
Vinyl Faced: 70˚ C maximum
Sheet
Applications
Isotropic
Plain Sheet
Thickness
0.5
0.75
0.5
0.75
0.5
0.75
Adhesive Backed Sheet
Matt Coloured Vinyl Sheet
(Available colours: Red, Blue,
Green, Yellow, White, Black)
Gloss Coloured Vinyl Sheet
(Available colours: Red, Blue,
Green, Yellow, White, Black)
Anisotropic
(Plain only)
Vinyl Thickness
0.1
0.1
Width
610
610
610
610
610
610
‡Length
30m
30m
30m
30m
30m
30m
0.5
0.75
0.1
0.1
610
610
30m
30m
Thickness
1.5
2.0
4.0
6.0
BH max
1.1
1.1
1.4
1.4
Width
250
250
250
250
‡Length
500
500
500
500
Strip
Drg. No.
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Vehicle Signs
Magnetic Printing
Cylinders
Sound Damping
Pads
Toys and Games
Magnetic Filters
Point of Sale
Displays
Planning Boards
TV Magnets
Teaching Aids
Shelf Markers
Ventilation Closers
Magnetic L Plates
Magnetic Badges
Paint Masks
Charting
Magnetic Alphabets
Applications
Diagram
Section
Coil
Length (m)
10232/1
7.9 x 4.3
50
11357
9.5 x 3.6
50
Standard
Magnetisation
Notes
M
M
M
10595
11
x 4.6
50
10596
15
x 6.4
30
13772
12.5 x 1.5
50
14167
19
x 1.5
50
16214
25
x 2.0
50
15324
(‘C” profile)
9.5 x 3.1
50
5 poles on
one face
15326
(‘C” profile)
19.5 x 3.1
50
10 poles on
one face
15328
(‘C” profile)
30
x 3.1
50
15 poles on
one face
15328
(‘C” profile)
50
x 3.1
50
16 poles on
one face
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
PLEASE NOTE THAT NON-STANDARD SIZES ARE ALSO AVAILABLE ON REQUEST
6 poles on
one face
8 poles on
one face
M
M
M
10 poles on
one face
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Door Closures
Double Glazing
Reed Switch
Operators
Planning Boards
Paper Guides on
Printing M/Cs
Magnetic Vice Jaws
Multipole Electric
Motors
TV Corrector
Magnets
Knife Racks
Magnetic Toys
Patio Door
Ventilators
Magnetic Signs
Shower Door Seals
Can Openers
Keyboards
Shelf Markers
Dimensions not otherwise
marked are mm.
Where inch (“) dimensions
are given, mm values are
conversions.
25
SPECIFICATION REQUIREMENTS FOR
ENQUIRIES
USEFUL MAGNETIC INFORMATION
Suggestions on Magnet Dimensions
General
For maximum economy, design so that fine tolerances are
not required. Do not specify tolerances that are not
necessary.
4
Surface Finish
It is common practice to specify surface finish as routine.
This may be justified for some mechanical components
but it is not appropriate for permanent magnets - it
increases costs without any advantage in magnetic or
mechanical performance.
If at all possible, avoid any specification of surface finish,
except for pole faces.
5
Direction of Magnetisation
In the case of anisotropic magnets and isotropic magnets
supplied fully magnetised, it is necessary for the
manufacturer to know the direction of magnetisation.
Anisotropic Magnets
Indicate the intended direction of magnetisation on
drawings.
On rectangular block magnets, avoid having the magnetic
length the same as any other dimension. If that cannot be
arranged, then the anisotropic preferred axis must be made
apparent by some obvious mark such as a bevel along one
edge.
ie:
It should be ensured that the direction of magnetisation is
clearly marked on the drawing. The recognised symbol
for the direction of magnetisation is:<—-M—->
6
Protective and Decorative Coatings
Unless otherwise specified, magnets are supplied without
protective or decorative coating. Typical finishes are paint
or zinc/nickel plate and this should be specified if
required.
7
Magnetic State
Some alloy magnets are not suitable for supply in the
magnetised state. However horseshoe and certain other
magnets may be supplied magnetised.
1
Quantities and Delivery Requirements
These affect the:a production batch size
b amount and type of tooling
c time factor for tooling
d cost
It is advisable to specify ‘magnetised in pairs’ or
‘magnetised with keepers’ or' magnetised in rows'.
2
8
Material
There are many materials available, each one with
special characteristics and all requiring different
dimensions for a particular application. Some are suitable
for production in certain shapes and sizes. Some cannot
be machined, except by grinding or are suitable for
magnetising in one direction only.
3
Machining
Except where there are sound reasons, it is good
practice to avoid machining and specifying tolerances.
The practice of showing a general tolerance which is
applicable to all dimensions often results in some
unnecessary grinding, adding to the cost. If tolerances
are not specified, it is understood that the magnets will be
supplied with the minimum of machining.
Ferrite, rare earth cobalt and NdFeB are always supplied
magnetised. It is important to specify the direction of
magnetisation for these materials.
Tests
If any particular performance is required then this should
be specified.
Magnetic properties are the main consideration during
manufacture. Other physical properties and working
conditions in use are not normally considered.
Tractive and gripping magnets are usually checked by a
weight lift test.
The magnetic characteristics given in this booklet are the
average value of rectangular test blocks. They are not
minimum guaranteed values and should not be used for
acceptance tests except in certain cases. When setting
test standards, the economic implications should be
considered.
Unnecessarily stringent tests can increase the cost of
testing, the scrap factor and therefore the price.
This also applies to physical dimensions and tolerance.
26
MAGNET CARE INFORMATION
How to avoid magnet damage
•
Once a magnet has been magnetised it is susceptible to magnetic damage, particularly when on ‘open circuit’. Magnetic
damage in the form of flux reduction is usually caused by exposure to stray magnetic fields. The damage is
instantaneous and can only be recovered by remagnetisation.
•
Storage is a common cause of damage which occurs to magnetised magnets. (Rare Earth and Ferrite are not susceptible to
magnetic damage of this nature).
•
Demagnetised magnets do not attract ferrous material and are immune to magnetic damage. Consequently, they may be
handled, shipped and stored without regard to magnetic considerations. About 90% of all Industrial Alnico type permanent
magnets are delivered to users in the demagnetised condition. However, magnets can be supplied magnetised if requested.
•
Magnetisation is generally a quick and easy process within the capability of any organisation. Advice on the design and
suitability of magnetisers will be given on request.
•
Please note that if an assembly is stripped down so that the magnet is placed on ‘open circuit’, the performance
advantage is immediately lost. Re magnetisation subsequent to re-assembly will restore the original performance.
•
A keeper (a piece of iron or steel that bridges the poles of a magnet when it is not in use) makes a magnet less
susceptible to magnetic damage and the attraction of ferromagnetic material is minimised.
Magnetic Damage
Do this
Separate by a direct pull. Reduce the pull by
breaking apart as shown.
Don’t do
this
Like poles repel.
Never allow this.
Rotating will cause like pole
to cross.
Placed like this both
magnets are damaged –
especially the one
on the right.
Never store magnets with
their sides on
ferrous materials.
Flux distorts and
causes weakening.
Magnetic damage is instantaneous and can
only be rectified by remagnetisation.
Permanent magnets at high temperatures
Optimum performances of permanent
magnets are largely due to
achievement of the most favourable
structures during manufacture - and,
of course, to those structures not
changing subsequently. Heat is the
agent that can cause structural
change.
Barium Ferrite and Strontium Ferrite
The curie point of this material is
450ºC. If this temperature is
exceeded structural change occurs. If
the curie point is not exceeded, the
reduction in performance on heating
is recovered after cooling. From -40ºC
to 200ºC the mean reversible
temperature coefficient is -0.19%/ºC.
The losses on heating from room
temperature are approximately:50ºC 100ºC 200ºC 450ºC
10%
20%
40%
100%
The recommended upper
temperature limits of use are 180ºC
for Sintered Ferrite magnets and
120ºC for Bonded Feroba.
Al-Ni-CO-Fe Alloys
Structural change occurs at
temperatures above 550ºC. If that
temperature is not exceeded the
reduction in performance on heating
is fully recovered on cooling. From 40ºC to200ºC the mean reversible
temperature coefficient is -0.02%/ºC.
The reversible losses (dependent on
the working point of the magnet) are
approximately:Flux density
after 1 hour
Length/ Holding
at holding
Dia.
temperature temperature
ratio
ºC
Tesla
9.9
590
1.027
10.0
600
0.945
10.0
635
0.900
7.1
700
0.610
100ºC
200ºC
300ºC
1%
1.5%
2.5%
400ºC
500ºC
550ºC
5%
9%
12.5%
The following are examples of
circumstances when magnets must
withstand the effects of very high
temperatures:• Incorporation of magnets in zinc
based or aluminium based die
castings
• Brazing pole pieces to magnets
• Neutron bombardment of magnets
in nuclear reactors
• Lifting ferromagnetic loads at high
temperatures
• Holding twist drills for salt bath heat
treatment
It can be categorically stated that for
such high temperature applications
the Al-Ni-Co-Fe alloys, of which
ALCOMAX, HYCOMAX and ALNICO
are typical, are the very best of all
permanent magnet materials. They
are, in fact, the only practicable
solution for such circumstances.
At 590ºC and above, the duration of
exposure to the elevated temperature
is a determining factor because
structural change will have
commenced. It must be emphasised
that the B/H working ratios of the
magnets are also significant.
% loss after further period at holding
temperature
2h 5h 10h 50h 100h 200h 500h
0.2 0.8 1.5 1.6
2.0
2.4
0.7 1.1 1.4 3.4
4.7
6.7
0.8 1.5 1.7 4.4
8.0 15.0 27.0
1.7 11.0 21.0 53.0 63.0
-
27
GLOSSARY
Air Gap
Load Line
A non-magnetic discontinuity in a magnetic circuit (i.e. the distance between
two magnetic poles). This gap often includes other materials such as brass,
aluminium or paint.
A line drawn from the origin of the Demagnetisation Curve with a slope. The
intersection of the -B/H curve and slope represents the operating point of the
magnet.
Also see Permeance Coefficient, Pc
Anisotropic Magnet
A magnet which has a preferred direction of orientation so that the magnetic
characteristics are optimum in one preferred direction.
Closed Circuit
Magnetic Circuit
An assembly consisting of some or all of the following: permanent magnets,
ferromagnetic conduction elements, air gaps, electrical currents.
This exists when the flux path external to the permanent magnet is confined
within high permeability materials which contain the magnet circuit.
Magnetic Flux
Coercive Force, Hc
Magnetising Force, H
The demagnetising force necessary to reduce observed induction B to zero
after the magnet has been brought to saturation. Coercive force is measured
in Oersteds or more recently A/m and kA/m.
The total magnetic induction over a given area.
The magnetomotive force per unit length at any point in a magnetic circuit.
This is measured in Oersteds.
Magnetomotive Force, F
Curie Temperature, Tc
This is the potential magnetic difference between any two points.
The temperature at which a material loses its permanent magnetic
properties completely and is no longer able to hold magnetism.
Maximum Energy Product, BH max.
Demagnetisation Curve
The second/left quadrant of the hysteresis loop, generally describing the
behaviour of magnetic characteristics in actual use. Also known as the
B-H curve.
There is a point at the Hysteresis Loop at which the product of magnetising
force H and induction B reaches a maximum. This maximum value is called
the Maximum Energy Product and is measured in Mega Gauss Oersted,
MGOe.
Oersted, Oe
Ferromagnetic Material
A material whose permeability is very much larger than one, and which
exhibits hysteresis magnetising and demagnetising characteristics. The
greater the flux carrying potential, the bigger the value i.e. one to several
thousands.
A unit measure of magnetising force (cgs). This is equivalent to Ampere
Turns per Inch (S.I.).
Permeance
The inverse of reluctance.
Flux
Permeance Coefficient, Pc
Magnetic flux is the condition existing in a medium subjected to a
magnetising force. This value is quantified by E.M.F. (electromotive force).
This measurement of force in cgs units is a Maxwell.
Pull Gap
Fringing Fields
Leakage flux particularly associated with edge effects and leakage patterns
in a magnetic circuit.
Gauss
Lines of magnetic flux per square centimetre. Gauss is measured in cgs
units, Maxwell lines and Webers per square metre or Tesla in the Si system.
Hysteresis Loop
A closed curve calculated by plotting corresponding values of magnetic
induction: B on the abscissa against magnetising force H.
Induction, B
Ratio of the magnetic induction to self demagnetising force. This is also
known as the 'load line' or operating point of the magnet.
Usually illustrated in graph format, these curves are a representation of the
relationship between the attractive force exerted by a magnet on a soft
magnetic workpiece and the distance between them. Pull Gap curve
diagrams are useful when selecting a magnet for a particular tractive or
holding application.
Reluctance, R
Reluctance is the resistance in a magnetic circuit and is related to the
magnetomotive force, F and magnetic flux (R =F/ magnetic flux) where F is
the magnetomotive force.
Remenance
This is the magnetic flux per unit area of section in the applied magnetic
direction of flux. This is measured in Gauss.
Remenance is the magnetic induction which remains in a magnetic circuit
after the removal of an applied magnetising force. If there is an air gap in the
circuit, the remenance will be less than the residual induction Br.
Intrinsic Coercive Force
Residual Induction Br
This is a measure of the resistance of the magnet material to a
demagnetising force. Permanent magnets with high intrinsic coercivity
values are usually classified as 'hard' permanent magnets. Intrinsic coercive
force indicates magnetic stability at high temperatures. Also see stabilisation.
Irreversible Loss
This is the partial demagnetisation of a magnet material when introduced to
external factors such as high/low temperatures and demagnetising fields.
Losses can only by rectified by remagnetisation. However, magnets can be
stabilised to prevent the variation of performance caused by irreversible
losses.
Isotropic Magnet
A magnetic material which does not have a preferred direction of magnetic
orientation and therefore can be magnetised in any direction without the loss
of magnetic characteristics.
This represents the maximum flux output from a given magnet material
measured at the point where the Hysteresis Loop crosses the B axis at zero
magnetising force.
Return Path
A magnetic circuit which provides a low reluctance path for the magnetic
flux.
Reversible Temperature Coefficient
A measure of the reversible changes in flux caused by temperature
variations.
Saturation
This is the condition whereby a magnet or ferromagnetic material has
reached a maximum value and an increase in the appliance of magnetising
force produces no increase in induction i.e. saturation flux densities for
steels range from 16,000 to 20,000 Gauss.
Knee of the Demagnetisation Curve
The point at which the B-H curve ceases to be linear. If the operating point
of the magnet falls below the knee, the magnet will not be able to recover
full magnetic potential without the application of a magnetising force.
Leakage Flux
This is the loss of magnetic flux which occurs through leakage caused by
saturation or air gaps introduced into the magnetic circuit. This induces a
loss of efficiency in the circuit which cannot be recovered.
Length of Air Gap, Lg
Indicates the length of the central flux path across an air gap.
28
Stabilisation
The process where a magnet is exposed to demagnetising influences
expected to be encountered in operation. The exposure to these
demagnetising influences such as high or low temperatures or external
magnetic fields prevents irreversible losses during actual operation.
Industrial
Product Support
Please contact the following for any assistance:
Tim Hollingsworth
Industrial Sales Manager
Alan Lyons
Technical Sales Engineer
Eclipse Magnetics Ltd
Atlas Way, Atlas North, Sheffield, S4 7QQ, UK
Tel: ++44 (0)114 225 0600, Fax: ++44 (0)114 225 0610
E-mail: [email protected]
Website: www.eclipse-magnetics.co.uk
For other Eclipse Magnetics products:
Kerri Ellis
UK Distribution Sales
Peter Rowsell
Export Development Manager
Mark Ward
VP Sales North America
[email protected]
Graham Thorpe
Technical Sales Manager - Handling Systems
& Workholding
Steve McAllorum
Technical Sales Manager - Separation & Filtration
Martyn Cotterill
Technical Sales Engineer - Separation & Filtration
WARNINGS
Health and Safety at Work Act, 1974 & Control of Substances Hazardous to Health (COSHH) Regulations 1988
In accordance with Section 6 of the above mentioned Act, every care is taken, as far as is reasonably practical, to ensure that products are
safe and without risk to health when properly used. However, inherent properties require that some precautions should be taken when using
or working on certain products.
Most permanent magnets are exceptionally hard and brittle. Fragments might be broken off, and can be projected at high velocities, when
subjected to abnormal shock or impact. Moreover, the magnetic forces are in some cases so great that such shock or impact could be
caused by two magnets jumping together. Magnetised magnets should be restrained mechanically, by non-magnetic spacers, from all such
tendencies.
Again due to the high magnetic forces, there is a risk of personal injury through trapped fingers if two magnets should jump together, or even
when a single magnet attracts its keeper or other ferrous matter. Magnets should be held in such a way that the fingers cannot possibly be
trapped.
Some permanent magnet materials contain cobalt. The limit for cobalt metal dust in the air is subject to Factory Act regulations. It is,
therefore, advisable that grinding operations on these materials be carried out in accordance with the regulations (Technical Data Note 2/73
– “Threshold Limit Values for 1973” – HM Factory Inspectorate).
Neodymium Iron Boron magnets burn spontaneously when machined without coolant; coolant should always be used when machining or
cutting these materials. Care should be taken that the swarf extracted from the coolant is not exposed to naked flames.
Ferrite magnets contain either Barium or Strontium elements which if consumed, can be injurious to health.
Certain Permanent Magnets, especially Rare Earths and unkeepered magnets, have very powerful magnetic fields. If these are brought near
to unshielded, sensitive equipment containing either permanent magnets or magnetic material components (mild steel etc.), they may have
either a demagnetising or a magnetising effect which could cause adverse operation of that equipment. i.e. pacemakers, computers and
tape, watches, credit cards etc.
Manufacturers Notes Although every effort has been made to ensure that the information contained in our catalogue is correct at the time
of printing, no guarantee as to its accuracy can be given or implied.
The company reserve the right to withdraw or amend any information, what-so-ever its nature, without notice. Availability of all types of
magnets and their specifications should be confirmed prior to proceeding with any design work.
Re: Transport by air of magnetised materials
(International Air Transport Association (IATA)
The magnetic field strength, for any package/ article, must be 0.00525 gauss or less, to be accepted for air transportation. Shipment
should be by sea or land wherever possible. If air transportation is unavoidable, magnets should either be in their demagnetised state or fully
keepered and/or shielded. Please note that extra keepering and/or shielding can be expensive and may be charged for at cost.
Eclipse Magnetics Ltd.
Atlas Way, Atlas North
Shefﬁeld S4 7QQ, England
T: +44(0)114 225 0600
F: +44(0)114 225 0610
E: [email protected]
Website: www.eclipse-magnetics.co.uk

cast alnico

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