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Bonding Magnets and Metals to Compose Magnetic Assembly

Posted on May 30, 2016

Bonding Magnets and Metal to make magnetic assemblies

In order to build an optimal adhesive joint between magnets and metals for a magnetic assembly, a detailed bonding process must be set up in advance. This process should include the following aspects:

  • For large magnetized magnets, it is necessary to design and fabricate jigs and structure tools for putting them into positions and holding them during curing period. Magnets of big size could repel or attract each other in magnitude of a few hundred pounds force and it would be impossible to fix them in given positions by hand. They could move in curing time. However, small magnetic assemblies, RB cups for example, are bonded in the automated assembly line by using computer controlled automatic glue filling machines.
  • For plated magnets and metals to be bonded for a magnetic assembly, sand and strip the coating then remove any dust, dirt, greases and other contaminations prior to bonding.
  • Select an optimum epoxy which are most compatible with both the magnets and the metals. Also consider the cure time and its maximum working temperature.
  • Wetting the mating surfaces of the magnets and the metals with the epoxy immediately before bonding they for a magnetic assembly
  • In order to get high shear strength and impact resistant joints, control the bond line thickness to be 0.005” approximately with proper spacers.
To test the bonding quality of an adhesive joint in a magnetic assembly, drop tests are widely used for small magnetic cup assemblies. For more elaborate tests of impact strength in shear and bonding durability, please refer to ASTM D950 and ASTM D4501.