After-market machining neodymium magnets.


Due to the fragile nature of neodymium magnets, after market machining can be a tedious process. Usually one only endured as a last resort for prototypes and low-quantity projects.

Below is a list of best practices for ensuring your magnets will be operational after modification.

     
1.) Neodymium magnets must be ground (Not Cut)
Magnets are brittle. For example: If you need to drill a hole in a neodymium magnet you cannot use a traditional Metal HSS drill bit as the magnet will chip or break. The material should be ground away slowly. The best bit for “grinding” a hole would be a cone shaped bit as shown below.
            
 
     

2.) Exposed neodymium will oxidize/rust.
Most of the neodymium magnets sold by Amazing Magnets are electro plated to avoid oxidization. When grinding away material the neodymium substrate is exposed and will need to be covered shortly after the modification is complete.
You can use a 2part epoxy such as JB weld to “re-plate” the magnet.
            
 
     
3.) Heat will cause a magnet to lose its strength.
Most of the neodymium magnets sold by Amazing Magnets have a maximum temperature of 80c/176F. If the magnet exceeds this temperature for an extended period of time it will lose its magnetism. When grinding away material from a magnet it is important to keep a bucket of cold water close by to dip the magnet and keep it cool. It is also important to dry the magnet directly after cooling it in the bath as the exposed neodymium substrate can quickly oxidize.
 
     

4.) Neodymium magnets can easily chip or break during machining.
Neodymium magnets are hard and brittle - like glass. The vibration, pressures, and shocks caused by grinding can easily chip or break neodymium magnets. Use rubber pads in your vice grip and other vibration damping methods to avoid breaking the magnets during machining. 


 

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