Machining and tolerances
Most alnico
magnets are manufactured using typical foundry
casting techniques, where the molten alloy is poured into sand molds.
Very small magnets, usually one ounce or less, are also produced using
the press and sinter techniques. Alnico is hard and brittle (45-55 Rockwell
C), and is not suitable for drilling, tapping or conventional machining
operations. Close tolerances are attained by abrasive grinding and cutting.
Standard tolerances for ground dimensions are +/-.005". Tolerances
for as cast dimensions vary with the actual part size. Un-ground surfaces
are gray to dark brown in color but are bright metallic after grinding.
Common applications
Magnetos •
Separators •
MRI • Sensors
• Holding magnets
• Security systems
• Relays |
Temperature constraints
and methods of magnetization
Alnico has the lowest temperature coefficient of any commercial magnet
material, providing for excellent stability over a wide temperature range.
A properly designed circuit usings alnico
magnets will have a stable flux
output during temperature fluctuations. Maximum operating temperature
for alnico is 950°F.
Magnetization: Alnico magnets
can be partially demagnetized
if like poles of magnets are brought together. Placing individual magnets
in contact with ferrous materials can also partially demagnetize them.
Care must be exhibited in handling magnetized magnets. Typical alnico
5 applications require a long magnetic length to pole surface ratio (usually
4:1 or greater) to insure good magnetic performance.
Added value services
Adams provides in-house cutting and grinding to meet your application
requirements. We also provide magnetic circuit design assistance to enable
you to choose the proper material and the proper size magnet to perform
the task you require.
Adams stocks a variety of shapes, sizes and grades of alnico. Alnico
5 is the grade most widely used but we also stock alnico 2, 5-7, 8 and
9.
Download product specifications in PDF format.
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Soft Ferrite Tools
