Injection Molded Magnets

Injection Molded Magnets

Injection molded magnets are essentially fully dense magnetic powders blended with a variety of polymer base materials.  Depending on the combination of magnetic material and polymer selected, a wide range of final material properties are possible.

Arnold typically works with a wide ranging combination of magnetic materials and polymers including:

  • Ferrite
  • NdFeB
  • SmCo
  • Nylon 6
  • Nylon 12
  • PPS

Selecting the right combination will impact the resistance of the product to moisture absorption, physical strength, magnetic properties, and even maximum operating temperature.

Injection molded magnets can be formed from very simple shapes to very complex shapes. Depending on the magnetic material, the parts may require magnetic orientation during the injection molding process to optimize the magnetic properties.

Temperature Characteristics

Maximum use temperature is a function of both the magnetic alloy powder and of the binder. For example, ferrite powders in nylon 6 or PPS have tested satisfactorily at 180°C. On the other hand, nylon 12 melts above 170°C and is not recommended for use above 150°C. Magnetic material such as the highest energy NdFeB grade, with intrinsic coercivity of 9,500 Oersteds (760 kA/m), suffers significant irreversible magnetic loss above 120°C, regardless of which binder is used. Maximum use temperatures are listed on each product’s specification sheet.

Tolerances

An important characteristic of injection molded magnets is that they conform dimensionally to the mold cavity which is precisely machined, the result being close tolerances in the finished product. What little dimensional variability there is results from shrinkage of the polymer during cooling. This depends upon part thickness and shape. Typical tolerances are +/-0.003 in/in. Closer tolerances on critical dimensions can be negotiated.

Product Availability Guide

Part No.Magnetic MaterialPolymerDensity (g/cc)Max. Br (Gauss)Max. Hc (Oe)Max. Hci (Oe)Max. Bhmax (MGOe)Max. Temp (ºC)
2039SrFerriteNylon 63.803,0702,5703,0702.35160
2040SrFerriteNylon 123.753,0602,5403,1902.34150
2046SrFerriteNylon 63.582,8902,5503,1502.11160
2048SrFerriteNylon 63.552,8802,5103,2101.99160
2049SrFerriteNylon 123.212,4602,3403,6001.52150
2051SrFerriteNylon 63.763,1302,5903,1402.41160
2052SrFerritePPS3.652,8802,5303,3202.05180
2070SrFerriteNylon 123.632,9402,5203,1902.17150
2071SrFerriteNylon 123.532,8102,6804,0202.05150
2101SmCoNylon 125.606,8806,00011,60011.28150
2103SmCoNylon 65.506,3806,00028,0009.72160
2202NdFeBPolyamide4.855,8004,32010,0007.15125
2204NdFeBNylon 125.205,3904,92013,2005.94150
2206NdFeBPPS4.404,4004,00010,5004.26150
2212NdFeBNylon 124.905,7204,3209,0006.63150
2213NdFeBNylon 125.205,8905,00010,0007.44150
2214NdFeBNylon 12/Polyamide4.654,8004,2009,8405.56125
2216NdFeBNylon 125.166,1104,8009,0006.63125
2217NdFeBPPS4.904,8204,80018,0005.17180
2218NdFeBNylon 125.205,8904,8009,6007.44150
2225NdFeBSpecial plastic5.706,8005,80010,2009.4150
2409SrFerrite/NdFeBNylon12/Polyamide4.154,6202,8804,3203.43125
2413SrFerrite/NdFeBNylon12/Polyamide4.725,2002,6404,4004.77125
2414SrFerrite/NdFeBNylon 124.855,3004,1009,1005.95150
2415SrFerrite/NdFeBNylon 124.003,8702,8304,2203.03150
2416SrFerrite/NdFeBNylon 124.975,4004,3109,4006.31150
2417SrFerrite/NdFeBNylon 63.852,2001,7402,6401.01150
2521SrFerriteNylon 123.652,8102,6804,0202.05150
2534SrFerriteNylon 63.532,7302,2503,3001.89150
2535SrFerriteNylon12/Polyamide3.652,8402,6504,0001.96125
2560SrFerritePolyamide3.652,8402,6504,0001.96125