Magnets in Motors: Ferrite vs Rare Earth
Motors rely on magnets for their rotation. Ferrite magnets and rare earth magnets being two of the most used types. Rare earth magnets, also known as neodymium magnets, are the strongest type of permanent magnets. They have a very strong magnetic field, around 1.4 Tesla, which is higher than ferrite magnets, about 0.5 to 1 Tesla. This is why rare earth magnets are famous for their strong and lasting magnetic field.
Ferrite Magnets
Ferrite magnets, also known as ceramic magnets, are made from a mix of iron oxide with one or more metallic elements. They are the commonly used magnets in electric motors due to their cost-effectiveness.
Advantages:
- Affordable: Ferrite magnets are made from a mix of iron oxide and barium/strontium carbonate. They are relatively inexpensive to produce and easy to magnetize.
- Resistant to Demagnetization: They are quite resistant to getting demagnetized compared to many other types of magnets.
- Corrosion Resistant: Ferrite magnets do not rust, so it doesn’t require extra coatings.
Disadvantages:
- Lower Magnetic Strength: Ferrite magnets are generally weaker than rare earth magnets. This may limit their use in applications requiring very strong magnetic fields.
- Brittle and Hard: They are brittle and can easily break or chip upon impact, so it cannot be used in machines where the magnet would experience significant stress or bending.
Rare Earth Magnets
Rare earth magnets, made from alloys of rare earth elements, are the strongest type of permanent magnets. They are divided into two main types: Neodymium (NdFeB) and Samarium Cobalt (SmCo).
Advantages:
- Powerful Magnetic Fields: Rare earth magnets can produce incredibly strong magnetic fields, making them ideal for applications a strong magnetic force is needed.
- Compact Size: Their strength allows for smaller, lighter designs of motors, which can be a huge advantage in applications like aerospace or portable electronics.
Disadvantages:
- Cost: Rare earth magnets are significantly more expensive to produce than ferrite magnets. Their price can be a limiting factor for certain projects or applications.
- Corrosion Prone: Without proper coating, rare earth magnets are susceptible to corrosion, which can degrade their performance over time.
