Surface Coating

Zinc Nickel Nickel-Copper -Nickel Au   Ag Phosphate Epoxy sealing

Plating Characteristics

Plating Type Overall Thickness Salt Spray Test Pressure Cooker Test
NiCuNi (Nickel Copper Nickel) 15-21 μm 24 hours 48 hours
NiCu + Black Nickel 15-21 μm 24 hours 48 hours
NiCuNi + Epoxy 20-28 μm 48 hours 72 hours
NiCuNi + Gold 16-23 μm 36 hours 72 hours
NiCuNi + Silver 16-23 μm 24 hours 48 hours
Zinc 7-15 μm 12 hours 24 hours


Each individual layer of Nickel and Copper are 5-7 μm thick. The Gold and Silver plating layers are 1-2 μm thick.
 Test results shown to allow comparison between plating options. Performance in your application under your specific test conditions may vary. Salt Spray testing conducted with a 5% NaCl solution, at 35°C. Pressure Cooker Test (PCT) conducted at 2 atm, 120°C at 100% RH.
 
 Table comparing main coating types
Once plated the Neodymium magnet is then magnetised. The Neodymium magnet is placed in a solenoid coil which is energised to produce a field at least 3 times the value of the magnet’s Hci. It is not unusual for Rare Earth magnets to be 'hit' with a field of 5T. The Rare Earth magnets sometimes have to be physically held in place within the coil otherwise the magnet may react to the applied magnetizing pulse and is propelled out of the coil (a bit like a bullet). The Neodymium magnet, being anisotropic, has a direction of magnetisation locked within its structure. When being magnetised, this direction of magnetisation within the structure aligns with the magnetising field. If the magnet is not aligned with the magnetising field, the magnet will violently spin to align up. It is possible for the magnet to break up / shatter due to the high rotational forces acting on the domains within the magnet. The magnet must be magnetised to saturation to get the maximum performance output. If the magnet is not aligned with the magnetising field, full saturation of Neodymium may not be achieved. The Neodymium magnet is made up of multiple domains (in simple terms, think of these as miniature magnets that make up the entire magnet). A very small proportion of domains are 'weak' and these 'relax' soon after the magnetisation. This is natural and cannot be avoided. The output drop is very small (much less than 0.5 % typically) and occurs very soon after being magnetised to saturation (it will have happened before the magnets have been packed for dispatch). Once done, the output of the NdFeB will not fall any further except by external demagnetising fields, raised temperatures, radiation or corrosion.

The Neodymium magnets are given quality control checks throughout the entire production process (dimensional checks, magnetic checks, visual checks). After magnetizing, the magnets are given a final check (they are tested for magnetic performance and are visually checked and dimensionally checked) and are then, having passed the quality control inspection tests, packaged for shipping to the customer.