Magnet #4966855

Cast Alnico 5 is the most commonly used of all the cast Alnicos. This material is used extensively in rotating machinery, meters, instruments, sensing devices and holding applications, to name a few. Excellent temperature stability, high residual induction and relatively high energies characterize Alnico materials, composed primarily of alloys of Aluminum, Nickel and Cobalt. They are manufactured through either a casting or sintering process. Cast magnets may be manufactured in complex shapes, such as horseshoes, not possible with other magnet materials. Sintered Alnicos offer slightly lower magnetic properties but better mechanical characteristics than cast Alnicos. Alnico is hard and brittle. Machining or drilling cannot therefore be accomplished by ordinary methods. Holes are usually cored in at the foundry and magnets are cast close to final size and then finish machined to closer tolerances. Alnico has a low coercive force and is easily demagnetized if not handled with care. For optimum performance of Alnico 5, the magnetic length should be approximately 5 times the pole diameter or equivalent diameter. For example, a 0.250" diameter magnet should be about 1.250" long. Because of its higher coercivity, Alnico 8 may be used in shorter lengths and in disc shapes.

Ceramic (Ferrite) magnets are sintered permanent magnets composed of Barium or Strontium Ferrite. This class of magnets, aside from good resistance to demagnetization, has the popular advantage of low cost. Ferrite magnets are very hard and brittle, and require specialized machining techniques. Moreover, they should be machined in an unmagnetized state. We are equipped to machine these materials to specifications. Anisotropic grades are oriented in the manufacturing direction, and must be magnetized in the direction of orientation. Isotropic grades are not oriented and can be magnetized in any direction, although some degree of greater magnetic strength will be found in the pressing dimension, usually the shortest dimension. Due to their low cost, Ferrite magnets enjoy a very wide range of applications, from motors and loudspeakers to toys and crafts, and are the most widely used permanent magnets today. Manufacturing Methods

Collectively known as Rare Earth magnets, Samarium Cobalt (SmCo) and Neodymium Iron Boron (NdFeB) magnets are alloys of the Lanthanide group of elements. Rare Earth magnets are the most advanced commercialized permanent magnet materials today. SmCo magnets are available in a number of different grades that span a wide range of properties and application requirements. SmCo magnets are brittle and machining operations should be performed prior to magnetization, using diamond tools. We are equipped to fabricate these materials to blueprint specifications. SmCo magnets are anisotropic, and can only be magnetized in the orientation direction. In general, magnetizing fields of about 35 to 45 kOe are required to saturate SmCo materials

Flexible sheet magnets, which are commonly used for refrigerator magnets, combine ceramic ferrite magnet powder with a flexible thermoplastic binder. The manufacturing process involves injection molding, which is well suited to high volume applications. The flexible nature of the material enables forming into intricate, tight-tolerance shapes. However, since the material is an alloy of ceramic ferrite material, the magnetic strength is weaker than a solid ceramic magnet. Still, the versatility of the flexible sheet enables its use in many applications. Flexible sheet is often magnetized in a multi-polar arrangement: N-S-N-S. The North and South poles are spaced close together, anywhere from 2 poles per inch to 60 poles per inch and up. This is useful in holding applications because a higher pole density results in higher holding forces. For a sensing application, a high pole density allows tighter resolution. Flexible sheets come in various thicknesses and widths. Thicknesses vary between 0.020" and 0.375". Widths vary from 0.187" up to 24". The material can be sold in strips up to 100 ft. long. Also, some come with an adhesive backing, which can simplify assembly if needed. The magnetic orientation is normally through the thickness. Our ProductsPermanent MagnetsAlnico MagnetsCeramic MagnetsNdFeB MagnetsSmCo MagnetFlexible MagnetsMagnet AssembliesMagnetic Couplings

Many factors must be considered when choosing a permanent magnet material for your application. We can make detailed recommendations for your particular application based on our years of experience and technical expertise. Factors including operating temperature, demagnetizing effects, environmental characteristics and available space all need to be considered. At VIONA, we can recommend materials, and we can assist in design.