Magnetic Component Engineering

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Fastening and Securing Magnets


Magnets are used to perform a function for the user. Generally, magnets need to be fastened or secured to other components. The best way to determine how to fasten the magnet to make your magnet system is to understand your options, then select what is most suitable.

Magnets are generally very brittle and hard. Fastening requires careful consideration. Below is a list of common systems utilized. If you are not sure, please call us and we will assist you. MCE is very experienced with the assembly of magnets in a magnet system.

Securing using Screws or Bolts

Advantages:

  • Generally, securing with a screw or bolt is considered reliable. 
  • Assembly is fast and can be automated.

Disadvantages:

  • Drilling a hole in a magnet is typically expensive because they are hard materials and machining is a slow process.
  • Magnets are generally brittle materials. If the screws are over torqued, excessive loads may be introduced on the magnet, causing it to fracture or break.

Welding

Advantages:

  • Systems welded in place can be very secure.
  • Hermetic seals are achievable.

Disadvantages:

  • Care must be taken to prevent the magnets from becoming exceedingly hot to prevent structural damage.
  • If the magnets are magnetized prior to assembly, care has to be taken so as not to exceed the magnet’s maximum operating temperature. Considerations have to be taken to prevent exceeding the magnet SYSTEM’s operating temperature too which might be substantially lower than the magnet material’s Tmax
  • The magnets must be held in a fixture during the welding process as to prevent movement during welding.
  • Electron Beam welding can only be performed on magnet assemblies that are NOT magnetized during the welding process, because the magnet’s field influences the electron beam.

Pressure Clamping

Advantages:

  • Magnets can be retained in position and remain secure.
  • Magnets can be used in a vacuum application without a concern of outgassing.
  • Assembly can be fast and automated.

Disadvantages:

  • Excessive pressure can fracture or break a magnet during the assembly process.
  • Tolerances on the magnet may need to be tighter than industry standards to ensure a consistent pressure.

Press Fitting

Advantages:

  • Magnets can be secured in position with high reliability.
  • The magnets inherent mechanical imperfections can be overcome specially for applications such as high speed or high rpm. Here, inherent cracks in the magnet could be masked.
  • Assembly can be automated.

Disadvantages:

  • Magnets must be manufactured to very tight tolerances.
  • Mating components must be manufactured to very tight tolerances.
  • Strong controls need to be in place to achieve the required interference fit, hence the required mechanical strength.

Cementing

Advantages:

  • Using advanced adhesives or epoxies can lead to very high strengths.
  • Assembly is quick and reliable for most applications.
  • Complex shapes can be constructed.

Disadvantages:

  • In vacuum applications, care must be exercised in the selection of adhesives and epoxies to prevent outgassing.
  • Epoxies and adhesives must be checked for possible expiration. Lot control data of epoxy or adhesive lot should be kept for traceability reasons.
  • In high temperatures, epoxies and adhesives lose their holding strength.