There are many magnet types that vary in strength, temperature and offer differing corrosion resistance. The most commonly used magnet types are neodymium (known as NdFeB, NIB or Neo magnet), rare-earth, samarium cobalt (SmCo), AINiCo (Aluminium, Nickel & Cobalt), and ferrites.
Adhesives have proved to be a popular choice for magnet bonding because of their high temperature resistance, fast cure speeds and ability to withstand impact, vibrations and shock, as well as preventing corrosion.
We explore the range of adhesives for magnet assemblies and how they can be used in applications from bonding electric motors to speakers.
Types of magnet bonding adhesives
Epoxy systems can form strong, resistant bonds to magnets. Speciality high-temperature motor magnet bonding adhesives can be used for Class H motors.
Araldite 2014-2 is a two component, thixotropic adhesive with good environmental and chemical resistance. Suitable for bonding metal and electronic components.
Methacrylate adhesives are fast curing adhesives with high strength and toughness.
Araldite Agomet F300 A/B
Araldite Agomet F300 A/B is a two component, no mix, fast cure adhesive for bonding metals such as steel, ferrites and other magnet materials.
Structural acrylic adhesives
Structural acrylic adhesives have fast setting times making them ideal for high- speed motor production. These adhesives are durable and have high impact strength, peel strength and resistance to polar solvents. These adhesives can be used on metals and ferrites.
Some recommended adhesives are:
Permabond TA437, a one component adhesive can be applied without an initiator providing one of the surfaces is metal. The fixture time is between 5 to 10 minutes before manoeuvre. This adhesive can be used for speaker applications such as pole piece to magnet assembly.
Permabond TA439 is a two component adhesive with a fixture time of 20-40 seconds. This adhesive is methacrylic acid free, making it suitable for use on sealed electric motors. An initiator such as Initiator 41 or Initiator 43 (for plastics) is recommended for this product.
Cyanoacrylate adhesives are easy to use and rapidly form high strength bonds, making them suitable for very small motors and speakers. These adhesives have very high shear strength, however are not as resistant to impact and polar solvents, compared to epoxies and structural acrylics.
Some recommended adhesives are:
Permabond 910 is a single part, low viscosity, metal bonding adhesive with a service temperature of up to 90°C (195°F). This adhesive can be used to bond magnets in a headset.
A toughened, flexible, gap filling, black adhesive with a service temperature of 120°C (250°F). Permabond 737 can be used for speaker applications, for example, bonding the dust cap to cone, surround to cone, cone to spider, voice coil to cone.
Permabond 820 is a low viscosity adhesive with a high temperature resistance of 200°C (390°F).
A single part, gap filling adhesive with a high temperature resistance of 250°C (482°F). It is recommended that you use Permabond 922 with a secondary heat cure.
When using adhesives, it’s important to prepare surfaces before bonding to ensure contaminants are removed from surfaces.
Read our surface preparation post here