Optimization of Magnetizing Parameters for Multipole Magnetic Scales Using the Taguchi Method

Magnetic encoders are widely used to identify the position or travel distance in machine tools in a harsh environment. A magnetic encoder comprises a magnetic sensor and a magnetic scale, which is a permanent magnet strip magnetized into a multipole configuration. The pole pitch, magnetic flux density, periodicity, and symmetry of a magnetic field pattern are crucial for signal processing to obtain a satisfactory resolution. The magnetic flux density and the accuracy of a magnetic scale with a qualified permanent magnet strip are determined using magnetization technology. This paper focused on the optimization of perpendicular magnetizing parameters, using the Taguchi method, for designing a magnetizer to fabricate the high-quality magnetic scales made of rubber magnets. The parameters included the thickness of the magnetizer core, diameter of the magnet wire, magnetizing current, and magnetizing gap. The optimal parameters of magnetization were determined, and the reproducibility was validated. The average magnetic flux density was increased by similar to 17% after optimization. In addition, the high-quality magnetic field pattern was achieved and it was advantageous for signal processing.