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Explore Our Ceramic Magnet Capabilities
- Ceramic magnets are a cost effective option for high volume applications.
- Ceramic magnet alloys offer good resistance to external demagnetization fields.
- Magnosphere can help optimize performance and cost with a variety of grades, including Ceramic 1, Ceramic 5, Ceramic 8, and Ceramic 8B in strengths ranging from 1.05 – 3.8 MGOe.
- Commonly used in motors, speakers and work holding assemblies.
Stock Ceramic magnets also available to reduce development and production lead times.
Available grades of ceramic magnets:
The range of Ceramic magnet alloy grades available from Magnosphere typically extends from 1.05 – 3.8 MGOe. This range allows for optimizing the cost, performance, and operational temperature resistance for a wide range of applications. Ceramic magnets have the lowest Energy Density of the commercially viable alloys, but are by far the most cost effective. Oftentimes sacrificing “space” and using more Ceramic / ferrite magnet alloy is a very good-trade-off for the low cost. As with all magnet alloys, Ceramic magnets should not be used as structural elements. They are very inherently brittle and will fracture or chip easily when mechanically stressed.
corrosion resistance:
Ceramic magnets are very resistant to corrosion. Coatings can be applied for cosmetic reasons or to reduce the fine, ferrite powder which is associated with Ceramic magnets. A Dura team member will assist with the selection of best surface treatment option for your Ceramic application.
temperature effects:
Ceramic (Ferrite) magnets are susceptible to demagnetization when exposed to temperature extremes. There are grades which have better resistance to high and low temperatures, but several factors will dictate the performance of the Ceramic magnet. One of the most pertinent variables is the geometry of the magnet or magnetic circuit. Magnets which are thin relative to their pole cross-section (Magnetic Length / Pole Area) will demagnetize easier than magnets which are thick. Magnetic geometries utilizing backing plates, yokes, or return path structures will respond better to temperature changes. The maximum recommended operating temperatures listed on the Ceramic magnetic characteristics page does not take into account all geometry conditions.
caution when using ceramic magnet in the cold
Unlike Neodymium, Samarium Cobalt, and Alnico, Ceramic magnets have a Positive Temperature Coefficient for the Intrinsic Coercive Force (Hci) (β). This means that as the temperature increases the magnet may exhibit an increase in net field. This is up to a certain point and the degree of increase is dependent upon the geometry of the magnet. The converse is also true and this is where some designs may have issues. As a Ceramic Magnet experiences a temperature decrease, the net field decreases. This is unlike all other commercial magnet alloys which experience a net field increase when the temperature decreases. Applications where failures may occur could be sensor trigger when the field is not sufficient to trigger a sensor in colder climates. Refer to the Available Ceramic Magnet Grades section of our website for specific thermal performance.
magnetization options:
Most useful commercial magnets are anisotropic, which means that they have an “Easy” or preferred direction of magnetization and that an orientation field was applied during the compaction stage of the manufacturing process.
It is essentially impossible to magnetize the resulting anisotropic magnet alloy other than in the Direction of Orientation; however, various pole configurations can be achieved without conflicting with the magnet material’s orientation.
Below are conventional and standard industry options for the MAGNETIZATION directions of Ceramic/ Ferrite Magnets.
disc geometry:
Polarity Nomenclature: Typically the arrowhead indicates the North pole of the magnet. For symmetric geometries indicating the location of a particular pole is unnecessary, but for non-symmetric geometries identifying a particular pole location is very important.
Example: An axially Magnetized disc magnet does not require communication as to the NORTH pole’s position, but a radial arc does. One must indicate if the NORTH pole is to reside on the Inner radius or Outer Radius.
block maget:
“Block Magnets” or Rectangular / Square magnets have three potential orientation directions. The block magnet can be polarized in any direction.
Multiple Poles on One-Face Can Be Achieved with Ceramic Magnets:
This image illustrates two poles, NORTH – SOUTH on one working face.
ring geometry:
Multiple Poles on One-Face Can Be Achieved with Ceramic Magnets:
This image illustrates four poles, NORTH – SOUTH – NORTH – SOUTH on one working face.
arc segment geometry
compliance and intellectual propert considerations:
Ceramic magnets manufactured by Magnosphere are compliant with Intellectual Property Rights, Environmental Restrictions, and Conflict Mineral usage.
- RoHS, RoHS II and REACH
Handling and storage of ceramic magnets:
Large Ceramic (Ferrite) magnets are very strong and brittle and appropriate handling and packing is required. Most receiving departments are not familiar with the strength of ceramic magnets and this can result in injury or broken parts. All personnel that may come in contact with this alloy should be made aware of the dangers of handling these magnets. The brittle nature of the alloy can lead to flying chips if the magnets are allowed to impact each other or a solid surface. Larger magnets can become a pinching hazard if caution is not exercised. We urge all customers to discuss handling techniques pertinent to their magnets with a Magnosphere team member.
ceramic magnets packaging
The packaging methods of magnetized alloy are dependent upon the magnet size and the customer requirement.
- Quarter-sized or smaller magnets are usually put attracting in rows. They may or may not have plastic spacers between them in order to reduce the attracting force between the magnets. These rows may be wrapped in corrosion inhibiting paper (VCI) and the wrapped rows are arranged attracting in a brick. The bricks may be skin package on cardboard or wrapped in foam.
- Magnets up to 2″ square will be arranged attracting in rows with sizable spacers between each magnet. The rows can be arranged attracting with spacers running the length of the rows or individually wrapped in foam. Smaller quantities of these large magnets can go into an appropriate cardboard box, but larger volumes must be crated.
- Large magnets, arrays, or assemblies will be packaged in wooden crates. Many times these products must be shipped via a LTL carrier.
ceramic magnets Shipping
A majority of our products are shipped ground by DHL, or LTL carriers. FAA guidelines consider magnetized material as hazardous goods when the field density emanating from the package sides exceed a specified value. Many air carriers will not accept magnetized material for air shipments. Dura Magnetics is able to ship magnets via air, but a packing/handling charge may be applied for larger volumes. These charges are only applied in extreme cases to cover the cost of extra shielding and packaging material, labor, and necessary paperwork.
ceramic magnets storage
Although Ceramic magnets are fairly inert, all magnets should be stored in a low humidity and mild temperature environment. The magnetized alloy is very strong and it will attract ferrous particles from the air and surrounding surfaces. These particles will accumulate and appear as small “hairs” on the surface of the magnet or packaging. To combat the accumulated debris, the magnets should be kept in closed, clean containers and left in their original Magnosphere wrapping. The magnets should remain in the attracting condition with all spacers intact. Metal shelving with poor clearance may cause the magnets to jump or shift as they are accessed. Do not store any magnetic material near sensitive electronics, equipment with cathode ray tubes (CRT), or magnetic storage media. Magnets which are not of the same alloy may need to be buffered from each other because of demagnetizing effects.
Ceramic magnet manufacturing methods:
Ceramic or Ferrite Magnets are produced by calcining a mixture of iron oxide and strontium carbonate to form a metallic oxide. A multiple stage milling operation reduces the calcined material to a small particle size. The powder is then compacted in a die by one of two methods. In the first method, the powder is compacted dry which develops an isotropic magnet with weaker magnetic properties, but with better dimensional tolerances. Oftentimes, a dry pressed magnet does not require finish grinding. In the second method, the powder is mixed with water to form slurry. The slurry is compacted in a die in the presence of a magnetic field. The applied field creates an anisotropic magnet which exhibits superior magnetic properties, but usually requires finish grinding.
The compacted parts which approximate the finished geometry are then sintered at high temperatures to achieve the final fusion of the individual particles. Final shaping is achieved by diamond abrasives. Usually the pole faces of the ceramic (ferrite) magnets will be ground and the remaining surfaces will exhibit “as sintered” tolerances and physical characteristics.