Permanent Magnets

ALNICO MAGNETS
This family of magnets was discovered in Japan in the mid-1930's. Arnold was the first US company to engage in research and manufacturing of alnico magnets starting in 1938. The Alnico (aluminum, nickel, cobalt) family of magnets remains the material of choice for many applications. Produced in both cast and sintered form at our facility in Marengo, IL alnico's outstanding temperature characteristics, high magnetic flux density, and excellent corrosion resistance are ideally suited for use in products of all sizes - from miniscule cellular telephone magnets weighing less than a gram to radar focusing magnets weighing 50 pounds or more. Arnold also manufactures assemblies using Alnico.

BONDED MAGNETS
Polymer bonded magnets have opened a new world of application opportunities. Thermo-elastomer and thermo-plastic resins can be compounded with a variety of magnetic powders to form Injection Molded. Injection molded magnets can be formed into complex shapes and molded directly onto other components reducing assembly costs. Flexible sheet and strip is used in many applications including small motors, flexographic (printing) devices, magnetic filtering, and signs.

HARD FERRITE MAGNETS
Hard ferrite (ceramic) magnets were developed in the early 1960’s as a low-cost alternative to metallic magnets (steels and alnico). Even though they exhibit lower energy when compared with other materials available today and are relatively hard and brittle, ferrite magnets have won wide acceptance due to their high resistance to demagnetization, outstanding corrosion resistance and low price per magnetic output.

ARNOKROME III™ IRON CHROME COBALT MAGNETS
Iron-Chrome-Cobalt permanent magnets are a malleable, magnetically semi-hard alloy which is available in cast form (see the Alnico Magnet section) and as thin rolled strip, bar, rod or wire from our Rolled Products facility. It is an excellent material for hysteresis coupling and for sensing applications. It is also a substitute for CuNiFe, which is no longer commercially available. Iron-Chrome-Cobalt is made and sold by Arnold under the trade name Arnokrome III™.

NEODYMIUM MAGNETS
Sintered neodymium-iron-boron (NdFeB) magnets, also referred to as "neo" magnets, have been commercially available since November 1984. They offer the highest energy product of any material today and are available in a very wide range of shapes, sizes and grades. Earliest use of neo magnets was primarily for voice coil motors (VCM's) in hard disk drives and this market still accounts for about 50% of total sales dollars. Other applications include high performance motors and generators, brushless DC motors, magnetic separation, magnetic resonance imaging, sensors and loudspeakers. Magnetic assemblies made from neo are also available from Arnold.

SAMARIUM COBALT MAGNETS
Our RECOMA® Samarium Cobalt magnets (also called rare earth magnets) were first commercially available about 1970. We offer two main variations: SmCo5 and Sm2Co17 and within these multiple grades of magnets from 18-32 MGOe (140 to 255 kJ/m³). These materials are stronger than ferrite and alnico magnets and widely used in high output motors and sensor applications where corrosion resistance, temperature stability, low weight and small size are important issues. Even with the introduction of neodymium iron boron magnets, samarium cobalt is still used where superior high temperature performance, excellent thermal stability or excellent corrosion resistance is required. Our RECOMA SmCo material is produced in Lupfig, Switzerland either as finished magnets or as blocks in a number of sizes to be finished into custom magnets. SmCo block material is stocked in the US, in Switzerland and also in the UK for fabrication into finished magnets or for use in samarium cobalt magnetic assemblies.