X-MINING Anisotropic SmFeN sensor magnets simulation with 2 poles outer circumference
[Analysis case: Magnetic field analysis simulation]

• You don’t know what kind of of alignment of magnet should you use to detect the angle of rotation with hall element and ring magnet?
• You don’t know how to construct the manet alignment of sensor magnet to detect the angle with hall element widely?
• You want to make a ring magnet in which the waveform of the surface magnetic flux density changes linearly with the angle.
• You want to make a magnetic sensor construction that can detect signals even if the distance between the sensing element and the magnet is increased.

By adjusting the orientation configuration of the Wellmax^TM SmFeN magnetic material, various surface magnetic flux density waveforms can be produced even with the same shape.

This case study shows how the waveform of surface magnetic flux density changes in several orientation examples, which were analyzed using the commercial magnetic field analysis software “JMAG”.

Step 1: Orientation analysis

Design several models of molds for magnetic alignment　with　permanent　magnets,　and　then　calculate　those　orientations and magnetic force of Wellmax^TM material during injection molding.

Step 2: Surface magnetic flux density analysis

Calculate the waveform of the surface flux density of the magnet with orientations obtained in Step1.

（Model）Magnet to simulate magnetic field analysis

・Shape of the magnet: Φ30×Φ24×L12 (mm)
・Magnetic matrial: Wellmax^TM-S3A12M
・Magnetic poles：2poles in outer surface
・Anisotropic type：Polar
・Specifications：Specifications：Examination of how the surface magnetic flux density waveform changes with orientation. (Axial center of magnet, Gap=0.5mm from magnet surface)
・Waveform：study item
・Accessories：None

Figure １　Shape of magnet

Analytical model

The orientation model was constructed using one or two permanent magnets (orientation magnets) per magnet pole.
For orientation analysis using magnetic field analysis, the angle of the orientation magnets and the material of the mold components were changed.

Figure 2 Example of magnetic circuit design

Result of analysis

The direction and magnitude of magnetization of Wellmax^TM magnetic materials filled in the cavities were calculated for each orientation model using the magnetic field analysis software “JMAG”.

Figure 3 Example of orientation analysis vector diagram in cavity

Analytical model

We used magnetic field analysis to simulate the waveform of the surface flux density of each magnet with the orientation obtained in Step 1 for the Wellmax^TM material.

Result of analysis

The odd-order component values of the waveform of the surface magnetic flux density of the magnet simulated by the magnetic field analysis for each orientation model were compared with the components of the triangular wave.

Figure 4 Example of orientation analysis vector diagram in cavity

Figure 5 Surface magnetic flux density waveforms of magnets in six orientation model patterns

Figure 6 FFT analysis results for six orientation model patterns.

The configuration of an orientation mold that satisfies the required characteristics of SmFeN injection-molded anisotropic bonded magnetic material (Wellmax™ material) was studied by magnetic field analysis simulation.
The surface magnetic flux density waveforms of the magnets varied greatly among the six orientation patterns considered, and results close to a triangular wave were obtained for the surface magnetic flux density waveforms of two