Magnets are often listed with values such as surface Gauss, remanence (Br), and pull strength. While these terms are related, they describe different aspects of a magnet’s performance. Understanding their distinctions is critical for engineers, buyers, and anyone selecting magnets for industrial or commercial applications.
What is Surface Gauss?
Surface Gauss is a measure of the magnetic flux density at the surface of a magnet, typically expressed in Gauss or Tesla.
- It represents the number of magnetic field lines passing through one square centimeter.
- A higher Gauss value means more concentrated field lines at that measurement point.
Key Point: Surface Gauss depends on magnet geometry (length, diameter, thickness) as well as grade. For example, increasing thickness often results in higher Gauss at the surface.
What is Remanence (Br)?
Remanence, often written as Br, refers to the magnetization retained by a magnet once the external magnetizing force is removed.
- It is typically measured in a closed magnetic circuit, where all field lines flow internally from North to South.
- In this condition, the magnet demonstrates its maximum intrinsic flux density.
Example: A horseshoe magnet with its keeper attached appears non-magnetic externally because all flux is flowing through a closed path internally.
What is Pull Strength?
Pull strength is a practical measurement of the maximum force required to detach a magnet from a ferromagnetic surface.
- It is usually expressed in pounds or kilograms.
- Pull strength depends on several factors:
- Magnet material and grade
- Magnet size and shape
- Contact surface area and flatness
- Presence of coatings or air gaps
Key Point: Pull strength is the most relevant measure for end-users seeking to understand how much weight a magnet can hold in real-world applications.
Open Circuit vs. Closed Circuit Flux Density
- Closed Circuit (Remanence Br): Magnet flux flows entirely through a ferrous path, unleashing maximum internal power with no external field.
- Open Circuit (Surface Gauss): Magnetism is emitted into the air and available for attracting objects. Gauss values in this state are much lower, typically below 7,000 Gauss.
Example:
A 10 mm × 3 mm N42 neodymium disc has ~3600 Gauss at the surface. Increasing thickness to 5 mm raises it to ~5100 Gauss.
Which Metric Matters Most?
- Surface Gauss → Best for comparing field strength at a specific measurement point.
- Remanence (Br) → Important for magnet designers and manufacturers.
- Pull Strength → Most useful for buyers and end-users who need to know how much weight the magnet can hold.
At HS Magnet, we measure all three parameters using calibrated equipment such as Gaussmeters, tensile pull testers, and certified reference magnets. Each product is clearly labeled with surface Gauss rating and maximum pull force to ensure accuracy and reliability.
Conclusion
While surface Gauss, remanence, and pull strength are related, they serve different purposes:
- Gauss describes magnetic flux density at a point.
- Remanence reflects the magnet’s intrinsic strength in a closed loop.
- Pull strength shows real-world holding capability.
For practical applications, pull strength often provides the clearest picture of performance. However, engineers and designers may rely more heavily on Gauss and remanence values for system integration.
Need help choosing the right magnet? Contact our HS Magnet team for expert guidance and product recommendations tailored to your application.
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