Neodymium Iron Boron

Benefits of NdFeB Magnets

Batch-to-batch Uniformity: The BHmax of our magnets has a Cpk greater than 1.6.

High Maximum Working Temperature: Our AH series of NdFeB magnets have working temperatures up to 230°C.

Excellent Adhesion of Plating to Magnet: Our magnets develop up to 2,175 psi attractive force between the plating and the magnet.

Excellent Corrosion Resistance: BJA Magnetics offers a number of coatings including, Nickel, Epoxy, Zinc, Tin, Phosphate, Parylene, Hybrid Coatings, Aluminum Spray coating, and IVD-Aluminum [Ion Vapor Deposition of Aluminum].

Low Surface Tension: Adhesives require a properly prepared surface for bonding. Good wet-ability is one of the keys to good bonding. The shear strength for our Ni Plated magnets is 50% greater than competitive magnets.

Improved Corrosion Resistance: The HAST protocol used on uncoated Neodymium Iron Boron magnets can qualitatively reflect the service life of the magnet. This test exposes the magnet to 130°C, 95% RH, at 2 ATM for 20 days. The magnet is massed before and after the test. Our magnets measure a weight loss of less than 3 mg/cm2. Competitors’ magnets can lose over 10 times more.

Surface Treatments: The corrosion resistance [sensitivity to oxidation] of NdFeB magnets is far better than it was just a few years ago due to changes in chemical composition. BJA Magnetics still recommends coating or plating for most applications. Plating NdFeB is a difficult process, and commercial plating houses are unlikely to be able to achieve plating with good adhesion. Nickel, Zinc, or Tin plating provides good corrosion resistance for NdFeB magnets.

NdFeB Coating, Sealing & Encapsulation

A variety of organic coatings have been successfully developed for NdFeB, exhibiting good corrosion resistance characteristics.

The latest advance in coating technology is Ion Vapor Deposition of Aluminum, typically referred to as “IVD Aluminum.” For especially harsh environments, it may be advisable to use a combination of coating techniques or to encapsulate the material in a sealed housing.

Organic Coatings: Epoxies, and urethanes are not hermetic (do not seal against moisture or oxygen), but do slow the reaction with the magnet.

Nickel: Electrolytic nickel provides a hermetic seal, but is prone to corrosion in salt, and acidic conditions. Electroless (chemical) nickel offers improved coating into crevices, internal threads, ID holes, but is less protective of the magnet.

Zinc Plating: Sacrificial, releasing particulates. By itself, the performance is marginal, so conversion coatings are often used in conjunction with zinc.

Aluminum IVD: A malleable coating that requires bead blasting, and conversion coatings to provide a good seal against the elements.

Conversion Coatings: Provides short-term protection only, but are used in conjunction with other coatings to enhance performance.

Combination Coatings: Typically nickel plating plus an organic overcoat; offers improved resistance to salt spray plus protection from moisture and oxygen.

Common Applications for Neodymium Iron Boron Magnets

• Holding systems requiring very high holding forces
• High field yoke magnets
• High performance stepper, DC, servo, linear, and voice coil motors
• Magnetic bearings
• Magnetic couplings
• Loudspeakers
• Halbach arrays
• Headphones
• Microphones
• Magnetic separation
• Instrumentation
• Switches
• Relays
• Magnetic resonance
• Sensor for Reed Switches, and Hall Effect devices
• Sputtering
• Vacuum deposition
• Charged particle beam guidance
• Particle accelerators
• Undulators
• Wigglers