Bonded / Plastics
Composed of a mixture of plastic bonding matrices and NdFeB or ferrite powders, they are obtained by injection, compression, extrusion or calendering molding processes. They are thus characterized by high versatility in size combined with magnetic materials of varying performance.
Injected plastic magnets
The injection process enables the fabrication of complex shapes with high precision and the insertion of other components such as shafts, metal inserts, etc. by overmolding.
Thanks to a larger plastic binder component than compressed magnets, injected plastic magnets have lower magnetic force values. In this type of plastic magnet the content of magnetic raw material, mixed with a PA6, PA12 or PPS plastic matrix, is generally between 83 and 93 percent. Injection molded magnets can be overmolded to other components all in one process.
Polyamide 6 (PA 6), polyamide 12 (PA 12), and polyphenylene sulfide (PPS) are used as a plastic matrix in injection molded magnets. Maximum operating temperatures depend on the magnetic raw material and the type of matrix: 160°C for PA 6, 140°C for PA 12, and 220°C with PPS, although always depending on the magnetic material used in the compound.
Compressed plastic magnets
When high flux density and a simple magnet shape, such as rings, disks or cylinders, are required, compression molding is preferable.
In NdFeB compressed magnets, the magnetic raw material is embedded in a thermoset plastic matrix. Epoxy resin is one of the main materials used as a plastic binder. They are axially pressed into molds. Since the percentage of NdFeB powder is close to 97 percent, much higher magnetic values can be achieved than with injection-molded magnets. The equipment used for injection molded magnets is less complex and less expensive.
In most cases, compressed plastic magnets do not require anti-corrosion surface coating. Neodymium plastic magnets have magnetic values between 2 and 12 MGOe while ferrite magnets range from 0.1 to 2.5 MGOe. The maximum operating temperature varies depending on the mixture used; they are generally between +130 and +160 °C.
Flexible magnets with simpler shapes are also obtained by extrusion and calendering processes and can be cut or die-cut to obtain the desired shapes, or adhesively bonded.
In addition to the wide versatility for the type of magnetization, these materials exhibit (BH) max energy values from 32 to 86 kJ/m3, with good temperature stability characteristics.
Plastic magnets, often known by the term “bonded magnets”, are finding increasing use in areas such as sensing, automation and measurement systems.
ODB Magneti is able to assist you in the development of your designs, from the drafting of initial configurations, to prototype realization, capable of meeting even the most specific application requirements.
The key features listed here are general; we are happy to provide assistance in determining the most appropriate product for specific applications.