A New High-Performance Plastic Magnetic Encoder 2009-01-1293

A high-performance, multipole, magnetic encoder has been developed using magnetic plastic and a stainless-steel armature, or slinger. This new multipole magnetic encoder exhibits higher magnetic performance, and is more durable in harsh environments in comparison to existing products made of rubber.

Three technical advances were applied to the development of this new multipole magnetic encoder: magnetic field injection molding technique, direct adhesion during injection molding, and enhanced durability of the magnetic plastic material. A higher magnetic flux density was achieved through the use of magnetic particles each having an easy axis of magnetization that are highly oriented due to the application of plastic injection molding in a magnetic field, which promotes a higher magnetic flux density than that of a magnetic rubber encoder. Applying the technology of direct adhesion during injection molding assures that the magnetic plastic adheres to the stainless-steel slinger, which provides a high degree of reliability that is equal to or higher than that of existing products. The high durability of the multipole magnetic encoder’s plastic material was achieved by modifying the resin binder of the magnetic plastic material.

Magnetic flux density of the multipole magnetic encoder, which was manufactured with proprietary techniques, is actually 25 % higher than that of a magnetic rubber encoder. Results from testing where the encoder was constantly exposed to severe conditions of heat, moisture, salt water, ozone, oil, and chemicals, prove that this newly developed multipole magnetic encoder offers a sufficiently high degree of endurance and reliability to meet the strict requirements of a hub bearing assembly.