FEMM Software Enhances Precision in Ndfeb Magnet Design

Selecting the optimal bonded neodymium iron boron (NdFeB) magnets can be challenging given the vast array of products available. This article reveals how finite element method magnetics (FEMM) can precisely determine key characteristics of bonded NdFeB magnets, enabling informed design decisions and enhanced product performance.

Bonded NdFeB magnets play critical roles in motors, sensors, loudspeakers, and numerous other applications. Their performance directly impacts product efficiency, precision, and reliability. However, as these magnets consist of magnetic powder blended with polymer binders, their properties are influenced by multiple factors including powder type, particle size, filling rate, and binder composition. Accurate characterization is therefore essential for design optimization.

Finite Element Method Magnetics (FEMM) is a robust open-source tool for simulating electromagnetic fields. Engineers can use FEMM to analyze magnetic field distributions, flux lines, flux density, and other critical parameters, enabling magnet design optimization and performance enhancement. The bonded NdFeB magnet parameters provided herein serve as valuable references for FEMM simulations.

FEMM's bonded NdFeB magnet parameters represent typical application values rather than specifications from individual suppliers, as performance varies between manufacturers. These parameters provide users with a reasonable starting point that can be adjusted to better simulate specific magnet behaviors.

The composite nature of bonded magnets results in extremely low electrical conductivity, typically 0.01 MS/m. This characteristic must be considered during electromagnetic simulations to ensure accuracy.

The relative permeability of bonded NdFeB magnets correlates with their energy product. Lower energy product magnets exhibit relative permeability values approaching 1, while permeability increases with higher energy products. Regression analysis of manufacturer data enables reasonable modeling of this relationship.

Unlike sintered magnets, manufacturers typically specify bonded magnet energy product ranges with nominal values positioned at the midpoint. For FEMM material definitions, assuming actual energy products equal nominal values simplifies modeling.

In the absence of standardized bonded magnet nomenclature, FEMM adopts a "BNX" naming system where "BN" signifies "Bonded NdFeB" and "X" represents the nominal energy product in MGOe. For example, BN5 denotes a bonded NdFeB magnet with 5 MGOe energy product.

FEMM includes bonded NdFeB magnet grades ranging from 1 MGOe to 10 MGOe in 1 MGOe increments. The table below details these grades' performance parameters:

Utilizing FEMM's bonded NdFeB magnet parameters enables accurate performance simulations and design optimizations, including:

• Magnet geometry optimization: Adjusting shape and dimensions improves field distribution and flux utilization.
• Grade selection: Choosing appropriate magnet grades based on application requirements.
• Performance evaluation: Simulating behavior under various operating conditions to assess reliability.

Accurate understanding of bonded NdFeB magnet properties is fundamental to design optimization. FEMM's parameters and simulation capabilities provide valuable insights for performance evaluation and decision-making. This methodology facilitates the development of competitive products through informed magnet selection and application.