How Bonded Magnets Are Made: A Comprehensive Guide

Jun 21, 2024 | Magnets, Material Grades

In the ever-changing world of magnet technology, bonded Alnico magnets represent a significant advancement. These innovative magnets offer unique benefits over traditional cast and sintered Alnico magnets, making them a valuable addition to various industrial applications. 

This post explores the fascinating process of creating bonded Alnico magnets, their properties, advantages, and industry impact.

What Are Bonded Alnico Magnets?

Bonded Alnico magnets are composed of Alnico powder and binders such as thermo-elastomeric (polyethylene, polyurethane), thermoplastic (nylon, PPS), or epoxy-based materials. These magnets are a relatively recent addition to the traditional Alnico line, designed to provide enhanced performance and versatility. 

Historically, Alnico magnets have been prized for their magnetic uniformity and temperature stability. The introduction of isotropic “bonded” Alnico magnets marks a significant innovation, broadening their application potential.

The Manufacturing Process of Bonded Alnico Magnets

The creation of bonded Alnico magnets involves several meticulous steps:

  • Powder Preparation: The process begins with carefully blending Alnico powder with a chosen binder and other chemicals. This mixture forms the foundation for the magnet.
  • Molding: The blended material is then compacted in a mold to create the desired shape. Unlike traditional methods, this process allows for the production of complex shapes, such as gear teeth, with extremely tight dimensional tolerances, eliminating the need for secondary finishing. 

Properties & Performance of Bonded Alnico Magnets

Bonded Alnico magnets exhibit distinct properties that set them apart:

Density and Temperature Limits

By controlling the binder’s dilution, these magnets have a density of approximately 50 to 80% of sintered Alnico. Their maximum operating temperatures, constrained by the binder and the powder’s reactivity, range from 0°C to 220°C.

Durability and Magnetizing Patterns

These magnets resist chipping and can accommodate complex magnetizing patterns, making them suitable for specialized applications.

Advantages Over Traditional Alnico Magnets

Bonded Alnico magnets offer several advantages compared to their traditional counterparts. Cast Alnico magnets are known for their excellent magnetic uniformity and temperature stability up to their maximum operating temperatures. 

The bonded versions maintain this consistency, with a temperature coefficient of Br of -0.02%/°C. This means they retain approximately 96% of their room temperature magnetization at temperatures up to 220°C, providing exceptional reliability under varying conditions.

Applications & Industry Impact

The unique variable properties of bonded Alnico magnets make them ideal for a wide range of applications across various industries.

Practical Uses

Common applications include electric motors, sensors, rotary encoders and precision instruments where complex shapes and tight tolerances are critical.

Future Prospects

As technology advances, the use of bonded Alnico magnets is expected to expand, driven by their versatility and performance. Continued innovation in binder materials and manufacturing techniques will likely further enhance their capabilities.

Bonded Alnico magnets represent a remarkable technological advancement, offering significant benefits over traditional cast and sintered Alnico magnets. Their unique properties (including extreme variation in properties), ability to create complex shapes, and consistent magnetic performance, make them invaluable in many industrial applications. 

For those seeking reliable and high-performance magnetic solutions, bonded Alnico magnets present an excellent choice. If you’re looking for the right bonded Alnico magnet for your next application, contact BJA Magnetics today to get started!

Search Here



Thank you so much Janice for your excellent customer service!
Cheryl N.
Thank you so much Janice for your excellent customer service!
Cheryl N.
Cheryl N.