In the years following, Arnold Engineering produced several other magne c lines. Tape wound cores became the third type of magne c material. They were made from nickel alloy tapes and are used in transformers and electronic control devices. Bobbin cores followed and were available in a wide range of sizes to suit the ul mate use of the core in electronic computer assemblies. In 1951, transformer cores (Silectron), made of grain oriented silicon steel, were produced to become Arnold Engineering's fi h magne c line. They were supplied in sizes weighing a frac on of an ounce to over a ton. In 1955, a line of iron powder cores was introduced. Their principal usage was in various radio, television, hearing aid, computer and aerospace applica ons. In 1964, Arnold Engineering formally announced its ceramic magnet line called Hard Ferrites. These products are used primarily in such applica ons as magne c separators, loudspeakers, holding devices, magne c chucks, and D. C. motors. In 1965, Arnold Engineering expanded its custom sli ng and rolling of various precision and highly-alloyed metals. Metals as so as copper can be rolled 50 mes thinner than a human hair. Such ultra-thin metal foil is custom rolled for use in electronic, electrical and aerospace applica ons. P 5 Ceramic Magnets Precision Thin Metals Wound Core Magnets