Choice of Materials

We can offer the complete range of magnet materials to suit different application and operating conditions.

Rare Earth Neodymium Magnets

Rare Earth Neodymium Magnets

Neodymium NdFeB magnets are, size-for-size, the strongest type of any magnet material that is commercially available (they are stronger than SmCo, Alnico and Ferrite).

Neodymium NdFeB magnets are often the ideal first choice for many applications because they offer a maximum performance from the smallest magnet volume.

Neodymium NdFeB should always be coated to guard against the risk of corrosion – NiCuNi, Zinc, NiCuEpoxy and Gold are popular finishes.

Advantages & Disadvantages of Neodymium Magnets

Positivities 

  • Maximum performance from smallest size.
  • Can be used in extremely cold conditions (e.g. in liquid nitrogen).
  • Standard Neodymium NdFeB is rated to +80 degrees C (176F) maximum. Can be rated to +100 (212F), +120 (248F), +150 (302F), +180 (356F), +200 (392F) and +220/230 degrees C (428/446F) with higher Hci versions.
  • High coercivity (Hci) to resist demagnetisation.
  • NxxT and L-NxxT alloys have better corrosion resistance than standard NdFeB but still needs coating.

Negativities 

  • Requires a protective coating to prevent the iron in the alloy from corroding (rusting).
  • NxxT and L-NxxT alloys are much more expensive and will still show signs of corrosion.
  • Higher temperature versions contain more Dy element increasing their cost.
  • Nd and Dy prices affect the production cost.
  • Above 150-180 deg C (302-356F), SmCo may be better.
Applications for Neodymium Rare Earth Magnets

Typical Applications for Neodymium Rare Earth Magnets

  • Motors and Generators
  • Meters
  • Automotive (clamps, sensors)
  • Aerospace
  • Separation (rods, grids, etc) – 10-12kG (22-26lbs) systems
  • High-performance magnetic clamps and pot magnets

Example: An automotive company required a thin disc shaped magnetic clamp to hold two mild steel sections together with maximum force. Even high-grade Neodymium NdFeB disc and ring magnets did not provide enough pull strength performance. Our solution was a dual polarity Neodymium disc magnet within a ring assembly creating a perfect magnetic circuit with a pull force meeting the specification.

Samarium Cobalt SmCo

Samarium Cobalt SmCo

Samarium Cobalt SmCo is the alternative Rare Earth magnet. It is often used in aerospace, automotive and military applications. It is usually weaker than NdFeB Neodymium at room temperature. Samarium Cobalt SmCo is capable of use in extremes of cold and heat. It also has very high coercivity making it ideal for high temperature motor applications. Samarium Cobalt also has extremely good temperature coefficients making the magnet output very stable with small changes in temperature. It is very popular in mission-critical sensing applications.

Advantages & Disadvantages of Samarium Cobalt Magnets

Positivities 

  • Can be used in extremely cold conditions (e.g. to a few Kelvin above absolute zero).
  • SmCo can be used up to +300 degrees C (572F); the H rated versions up to +350 degrees C (662F).
  • High coercivity (Hci) to resist demagnetisation.
  • Above +150 to +180 degrees C (302-356F) the SmCo starts to offer more performance than NdFeB grades.
  • SmCo is regarded as being corrosion resistant.
  • Very low field strength change with varying temperature.

Negativities

  • Sm2Co17 should be given a protective coating when in very damp conditions to minimise any surface corrosion risk (Sm1Co5 does not rust as it contains no iron).
  • Generally higher cost than NdFeB.
  • All magnets are brittle but SmCo is the most brittle.
Application of Samarium Cobalt

Typical Applications of Samarium Cobalt

  • High-temperature Motors and Generators
  • Military applications
  • Automotive (sensors)
  • Aerospace (sensors)
  • Magnetic pump couplings
  • Oil drilling applications
  • Cryogenic applications

Example

magnetic pump coupling was required to cope with high temperatures up to and possibly over +300 degrees C (572F). We supplied the H rated SmCo which will cope with temperatures up to +350 degrees C (662F).

Ferrite Magnets - Magnet Materials

Ferrite (Ceramic)

Ferrite Magnets are corrosion resistant - they can be used in water with no corrosion at all. Although not as powerful as Rare Earth magnets, their high coercivity and relative low cost make them ideal for use in motors and high temperature motors.

  • Ferrite magnets are ideal for low cost applications.
  • Ferrite magnets are also electrically insulating - they do not allow eddy currents inside them.
  • Ferrite magnets are great for higher temperatures but not ideal in very cold applications.

Advantages & Disadvantages of Ferrite Magnets

Positivities 

  • Do not corrode in water.
  • Can be used up to +250 degrees C (482F)
  • Sometimes up to +300 degrees C (572F) in special circumstances.
  • High coercivity (Hci) that increases as magnet heats up.
  • Electrically insulating.
  • Low cost.

Negativities

  • Not as strong as Rare Earth Magnets – typically offering around 1/7th the pull force of similarly sized NdFeB.
  • Specialised shapes can carry tooling charges.
  • When taken to around -20 degrees C (-4F) and colder, the Intrinsic Coercivity (Hci) falls to a level that risks the magnet possibly starting to demagnetise (depending on the shape and the application).
Applications for Ferrite Magnets

Typical Applications for Ferrite Magnets

  • Motors and Generators
  • Meters
  • Marine applications
  • High temperature applications.
  • Lower cost pot magnets and clamping systems
  • Loudspeakers
  • Overband magnets

Example: A company was using NdFeB Neodymium magnets to clamp onto hot mild steel surface - the magnets were struggling to perform and cost was an issue. We supplied ferrite pot magnets which not only provided sufficient direct pull force but the pot magnets could handle the high temperatures, the magnets could not be damaged by being protected by the pot magnet design and the system was also cheaper and easy to maintain.

Alnico Magnets - Magnet Materials

Alnico Magnets

Alnico magnets have the best temperature coefficients of any magnet material. Alnico magnets are a best choice in extremely high temperature applications.

Alnico magnets are Cast or Sintered.

Weaker Isotropic alnico takes complex magnetic fields. Stronger anisotropic alnico has a fixed DoM axis.

Cast Alnico 5 is the most common grade of Alnico, with the LNG44 variant of Alnico 5 (Alcomax 3) being the most popular.

Advantages & Disadvantages of Alnico Magnets

Positivities

  • Cast Alnico offers a near net shape. Cast alnico can be produced to complex shapes with complex magnetic patterns.
  • Alnico Br as high as NdFeB at room temperature.
  • Can be used up to 450-550 degrees C (842-932F).
  • Least variation in magnetic output with temperature change of any magnetic material.
  • Can be cast in very large sizes.

Negativities

  • Sintered alnico is usually limited to small to medium sizes and simpler shapes.
  • Low coercivity (Hci) making them easy to demagnetise.
  • Complex cast alnico sometimes needs sand mold tooling which can be expensive if existing tooling is not available.
Alnico Magnets Application

Typical Applications for Alnico Magnets

  • Very high temperature applications
  • Use in hot oils
  • Clamping
  • Motors and Generators
  • Mass spectrometers
  • Precision sensors and meters
  • Aerospace

 

Example

A company was using Alnico to operate a Mass Spectrometer but they were struggling to achieve the required magnetic field to detect the materials they were testing for.

The solution was to use a higher strength of Alnico magnet assembly and then deliberately use the low coercivity of alnico to demagnetise it slightly to tune the magnetic field in the assembly air gap to the required field strength.

The thermal stability of the alnico meant that the field would be stable enough for the entire operation of the unit. In the laboratories.

Flexible Magnets Rubber

Flexible Magnets (Rubber)

Eclipse Magnetics understands the needs of the product designer, graphic designer, printer, marketing manager and end user. We offer a comprehensive range of magnets and magnetic products to meet the marketing and advertising needs for Point of Sale displays, packaging products and signage. Flexible magnets are produced by a ferrite magnet material mixed with a flexible rubber binder which is then extruded or calendared to create profiles, tapes and sheets. Because the binder is flexible, the material can be rolled. The flexible magnetic rubber is multiple poled on one side (some versions, termed anisotropic) is magnetic on both sides. Extra options include vinyl finish, dry wipe, printed, etc.

Advantages & Disadvantages of Flexible Magnets

Positivities

  • Low cost.
  • Can generally be rolled up for storage and ease of transporting around.
  • Can print onto the vinyl surface to create bespoke visual displays.
  • Can be produced in a customised manner for practicality e.g. adding ferrous sheet and printed vinyl so magnets would attract to the ferrous layer in magnetic maps.
  • Can add adhesive backing layer.

 

Negativities

  • Binder softens at +50 to +70 degrees C (122-158F) and higher and the magnetic performance is lost.
  • The material stiffens as it gets colder.
  • Below around -20 degrees C (-4F) the ferrite starts to lose its performance by demagnetisation.
  • Some options cannot be rolled up (e.g. magnetic rubber plus ferrous sheet plus vinyl plus dry wipe combination is laminated together so should not be rolled up).
Flexible Magnets Applications

Typical Applications of Flexible Magnets

  • Vehicle magnetic graphics.
  • Magnetic signs and displays (Point of Sale).
  • Advertising.
  • Magnetic maps, charts, music boards.
  • Painting booth magnetic covers.
  • Magnetic gaskets.

Example: A customer wanted to convert their magnetic white board to a customised planning chart that is removable. The solution was to take their artwork for the chart, print it onto white vinyl coated magnetic rubber and add a dry wipe finish so whiteboard pens could be used on it.

Electromagnets

Electro-magnets

Eclipse Magnetics understands the needs of the product designer, machine designer, electrical engineer, safety manager and end user. Electro-holding magnets can be simple electromagnets or electropermanent magnets. Electromagnets are a wound copper coil with a central steel core within a steel housing– they only create magnetism and clamp onto mild steel when a dc electrical current is present (energise to hold).

Electropermanent magnets are electromagnets with permanent magnets inside them as well – the magnet clamps to the mild steel when no current is applied but when the dc current is applied the magnetic paths change and clamping is stopped (energise to release). The energise to release electromagnets are always "on" when no current is present.

Advantages & Disadvantages of Electro Magnets

Positivities

  • Extremely high clamping forces are possible
  • Over 1600N for a 65mm (2.6ins) diameter electromagnet
  • They can be connected in series or parallel (parallel is regarded as a better method) when using several
  • Electropermanent magnets stay clamped when no current is present
  • Can be operated remotely
  • 12V dc, 24V dc and 240V ac versions exist

Negativities

  • Electromagnets only clamp when a current is applied
  • Electromagnets require a power supply
  • Pull force reduces as the air gap increases
  • Pull force reduces for thinner mild steel (using several smaller electromagnets is advised in such situations)
Applications for Electromagnets

Typical Applications for Electro Magnets

  • Machine tools
  • Door locking / holding
  • Feeder mechanism, Short stroke / high force operation
  • Automation e.g. Textile machinery, Packaging machinery, Office machinery
  • Grill locking
  • Remote hold / releas

Example: A company required a system to clamp mild steel sections and move them around within a confined area, ideally with the ability to clamp and release on a robotic system. We supplied them with energise to release electropermanent magnets that they can control automatically at a distance to their requirements.

Bonded/Molded Magnets

Bonded/Molded Magnets

Compression molding uses a solid binder (e.g. a plastic or thermosetting epoxy) plus the magnetic material. The end material is isotropic - the magnetising coil fixture design determines the magnetic pattern it takes.

Compression molding is cost effective when higher volumes are required compression molded magnets are best produced in tens or hundreds of thousands of magnets per production run.

Injection molding uses a solid binder (e.g. a plastic or thermosetting epoxy) plus the magnetic material but gives a greater variety of shapes and complexity of shapes compared to compression bonded. The end material is isotropic - the magnetising coil fixture design determines the magnetic pattern it takes.

Overmolding is possible with injection molding process.

Injection molded magnets are produced in tens or hundreds of thousands of magnets per production run.

Advantages & Disadvantages of Bonded/Molded Magnets

Positivities

  • A higher ratio of magnetic material powder to binder gives higher magnetic performance than the injection molded magnets (higher magnetic loading)
  • NdFeB, SmCo, Alnico and Ferrite versions possible
  • Hybrid versions as well (e.g. Ferrite+NdFeB) with combined properties
  • Good tolerances – secondary machining not needed
  • Low electrical conductivity, low eddy currents

Negativities

  • The compression bonding process is limited to simpler shapes such as rectangles, rings, arcs and cylinders. A consistent cross sectional area is required along the pressing direction
  • Possible tooling charges for production and magnetising
Blonded and Molded Magnets Application

Typical Applications of Bonded/Molded

  • Motors
  • Position sensors
  • Hybrid performance components

Examples: A company wanted a magnet on a joystick to activate Hall Effect sensors to give relative position information. A ferrite magnet would be too weak; a sintered NdFeB neodymium magnet would be too powerful. A compression bonded NdFeB magnet was supplied that had a performance between NdFeB and Ferrite but which had an epoxy finish, good final tolerances and would be low cost in high production quantities.

Injected Molded Magnets

Injection Molded (Plastic) Magnets

Injection molding uses a solid binder (e.g. a plastic or thermosetting epoxy) plus the magnetic material but gives a greater variety of shapes and complexity of shapes compared to compression bonded. The end material is isotropic - the magnetising coil fixture design determines the magnetic pattern it takes.

Overmolding is possible with injection molding process. Injection molded magnets are produced in tens or hundreds of thousands of magnets per production run.

Advantages & Disadvantages of Injection Molded (Plastic) Magnets

Positivities

  • More complex shapes are possible
  • Overmold, insert mold, etc all possible
  • NdFeB, SmCo, Alnico and Ferrite versions possible
  • Hybrid versions as well (e.g. Ferrite+NdFeB) with combined properties
  • Low electrical conductivity, low eddy currents
  • Good tolerances. More resistant to chipping than compression bonded

Negativities

  • Injection molded magnets offer lower magnetic performance than the compression bonded magnets (due to lower magnetic loading)
  • Possible tooling charges for production and magnetising
Typical Applications of Injection Molded (Plastic) Magnets

Typical Applications of Injection Molded (Plastic) Magnets

  • Motors
  • Sensors
  • Injection molded rotor assemblies
  • Insert molded magnetic components
  • Overmolded magnetic components

Example: A company required a ring magnet with multiple poles around the outer circumference for rotary movement sensing. An injection molded ferrite magnet was magnetised with a dedicated magnetising fixture to create the required multiple pole pattern. The ring also had a slot added to fit onto the keyway on a shaft to locking in place in the assembly.

Soft Ferrite Magnets

Soft Ferrite Magnets

Soft ferrites are not permanent magnets. They carry magnetism (like mild steel) but as soon as the magnetic field is removed, the magnetism disappears. Soft ferrites are popular as transformers (to change the voltage from primary to secondary windings). So soft ferrites are often called transformer ferrites. Soft ferrites exist as toroids (rings), C shapes, E-shapes, curved shapes, etc. Other shapes are possible. They often have performance criteria such as permeability and inductance.

Advantages & Disadvantages of Ferrite Magnets

Positivities

  • Carry magnetism effectively with low losses
  • Can handle alternating currents

 

Negativities

  • Have different properties such as inductance and permeability so care is required to get a correct material type
  • It will be expected that the customer knows exactly what they require
Typical Applications for Ferrite Magnets

Typical Applications for Ferrite Magnets

  • Power conversion
  • Line filters
  • Radio frequency applications
  • Transformers

It is expected that the customer will know the size, shape and performance characteristics of the soft iron material that they require. We do not currently offer technical design support for this product range.

Iron Chrome Cobalt FeCrCo

Iron Chrome Cobalt FeCrCo

Iron Chrome Cobalt magnets (FeCrCo) have similar properties to cast Alnico 5 but, unlike cast alnico, the FeCrCo magnets are actually reasonably malleable. The FeCrCo magnet material is semi-hard magnetically and exists in bar, rod, wire and also as thin rolled strip. They are a replacement for CuNiFe magnetic material (CuNiFe is not commercially available any more).

Advantages & Disadvantages of Iron Chrome Cobalt Magnets

Positivities

  • Malleable – FeCrCo is easier to machine than Alnico
  • FeCrCo can be hot deformed
  • The maximum recommended operating temperature is typically around +400 degrees C (752F)
  • FeCrCo has a Hc varying typically from 50kA/m to 300kA/m. The value of Hc produced depends on the method of the final heat treatment (timescale, temperature and quench rate)
  • FeCrCo usually does not require any corrosion coating

Negativities

  • If the final heat treatment is not performed, the magnetic performance is very poor
  • The strips are usually thin. Thicker sheets and plate are not really possible
  • Easily demagnetised or remagnetised in a different direction
Typical Applications for Iron Chrome Cobalt Magnets

Typical Applications for Iron Chrome Cobalt Magnets

  •  Compasses
  • Hysteresis coupling applications e.g. a multi-pole permanent magnet rotor turning a FeCrCo disc by hysteresis

Example: A company wanted a customised needle for a compass they were designing. The needle could be produced to the shape, heat treated, painted and magnetised to their requirements.