Bonding Magnets and Metals to
Compose Magnetic Assembly
Posted on May 30, 2016
In order to build an optimal adhesive joint between magnets and metals for a
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.