Technical Journal : Industrial Furnaces for Magnets for Vehicle Motors

Industrial Furnaces for Magnets for Vehicle Motors

Magnets are produced by means of many processes, such as the alloy production process, hydrogen embrittlement process, sintering process, and grain boundary diffusion process. To produce the highperformance magnets required for use in vehicle motors, ULVAC provides an appropriate furnace for each process. The “Magcaster-600” is a melting furnace for the alloy production process for producing magnets with good grinding characteristics. The “FHH series” includes hydrogen furnaces for the hydrogen embrittlement process without exposure to the air. The “FSC series” provides inline-type heat treatment furnaces for the sintering and aging processes. The “Magrise series” features heat treatment furnaces for the grain boundary diffusion process used to defuse heavy rare metals into neodymium. This article introduces the features of the line of furnaces manufactured by ULVAC for the production of magnets for installation in vehicle motors.


Since people first began using automobiles, a wide variety of technologies have been developed. As these technologies advanced, motors began to be used in various parts of automobiles.
Motors are especially important in hybrid vehicles and all-electric vehicles, which use motors to provide motive power.
One of the parts essential to motors is the permanent magnet. Because an alloy consisting of neodymium (Nd), iron (Fe), and boron (B) is its main component, this magnet is generally called a neodymium magnet and is considered the most powerful among permanent magnets. Because neodymium magnets are powerful, they are extremely useful when it is necessary to reduce the size,
thickness, and weight of devices that require permanent magnets, and therefore are widely used. However, a weak point of neodymium magnets is the fact that their magnetic force weakens at high temperatures. This phenomenon in which a neodymium magnet loses its magnetic force
(magnetic characteristics) at high temperatures is called heat-induced demagnetization.
This phenomenon typically occurs in neodymium magnets when their temperature rises
to several hundred degrees. When a neodymium magnet is incorporated into a motor used in an automobile, it is being used in a hightemperature environment. Consequently, the magnet cannot
be used as is because of the heat-induced demagnetization phenomenon mentioned above. To solve this problem, many innovative steps have been taken in developing industrial
furnaces to be used for manufacturing on-board motors. This paper introduces the characteristics of industrial furnaces to be used for manufacturing magnets, which ULVAC has already delivered to neodymium magnet manufacturers.