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Protective Coating for Magnetic Materials

IP.com Disclosure Number: IPCOM000049820D
Original Publication Date: 1982-Jul-01
Included in the Prior Art Database: 2005-Feb-09
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Dickie, HG: AUTHOR

Abstract

Precision permanent magnets forming part of the stator of an electric motor or actuator are encapsulated by electrophoretic coating. This prevents contamination of the environment of the motor with easily shed magnet material without compromising dimensional tolerances.

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Protective Coating for Magnetic Materials

Precision permanent magnets forming part of the stator of an electric motor or actuator are encapsulated by electrophoretic coating. This prevents contamination of the environment of the motor with easily shed magnet material without compromising dimensional tolerances.

Electric motors and actuators are frequently employed in magnetic disk files in which particulate contamination of the head/disk environment must be strictly controlled. Such actuators and motors generally employ a number of permanent magnets to provide the working flux across an air gap of precise dimensions. The magnetic materials employed are often brittle and susceptible to chipping or flaking unless coated with a protective coating. Traditional varnish or paint coatings are difficult to apply with the control of thickness which would be necessary when the magnet defines an air gap in which a coil rotor moves.

It has been found that a suitably thin protective coating of precise thickness can be produced electrophoretically. In one specific example, ferrite permanent magnets are first electrolessly plated with 1000 angstroms of copper or nickel. The precoated magnets are then placed in an electrophoretic coating bath employing an acrylic paint and connected as the anode. A coating of 0.025 to
0.030 mm thickness of acrylic is deposited and subsequently cured. The electrophoretic process has the advantage of being self-limiting.

If the permanent magnet ma...