The following points should be considered when designing magnet assemblies.
Affixing Magnets to Housings
Magnets can be successfully affixed to housings using adhesives. Cyanoacrylate adhesives which are rated to temperatures up to 180° C with fast cure times avoid the need for fixtures to hold the magnets in place while the bond cures. Adhesives with higher temperature ratings are also available, but these require oven curing and fixturing of the magnets to hold them in a vacuum. Potential outgassing of the adhesives should be considered.
When arrays of magnets must be assembled, especially when the magnets must be placed in repelling positions, it is very important to consider safety issues. Modern magnet materials such as the Rare Earths are extremely powerful, and when in repulsion they can behave as projectiles if adhesives were to break down. It is recommended that in these situations mechanical fastening be included in the design in addition to adhesives. Potential methods of mechanical retention include encasement, pinning, or strapping the magnets in place with non-magnetic metal components.
Magnet assemblies may be potted to fill gaps or to cover entire arrays of magnets. Potting compounds cure to hard and durable finishes and are available to resist a variety of environments, such as elevated temperatures, water flow, etc. When cured, the potting compounds may be machined to provide accurate finished parts.
Assemblies which are required to be hermetically sealed can be welded using either laser welding (which is not affected by the presence of magnetic fields) TIG welding (using appropriate shunting elements to reduce the effect of magnetic fields on the weld arc). Special care should be taken when welding magnetic assemblies so that heat dissipation of the weld does not affect the magnets.