Remanence
Residual magnetic flux density at zero applied field after saturation.
T · mT · G · kGFROM MATERIAL TO COMPONENT
Understand the Field.
Define the Part.
Magnetic quantities, clear calculations and the interfaces that shape a component.
READ THE MATERIAL DATA
Four Quantities. Different Roles.
Compare the same quantity, units and test conditions.
Normal Coercivity
Reverse field strength at which magnetic flux density B reaches zero.
A/m · kA/m · OeIntrinsic Coercivity
Reverse field strength at which magnetic polarization J reaches zero.
A/m · kA/m · OeEnergy Product
Maximum magnitude of B × H on the second-quadrant normal demagnetization curve.
kJ/m³ · MGOeRemanence is a material property. The field at a working point also depends on magnet geometry, the magnetic circuit and the gap.
PRACTICAL REFERENCE TOOLS
Make the Numbers Clear.
Conversions and worked examples for preliminary engineering discussions.
UNITS
Convert a Magnetic Quantity.
1 T = 10 kG
A unit conversion does not determine a product's performance or material grade.
WORKED EXAMPLE
Temperature and Remanence.
Assumed inputs below illustrate a linear calculation. They are not an Empire grade specification.
Bᵣ(T) = Bᵣ(T₀) × [1 + αBᵣ × (T − T₀) / 100]
Use a coefficient established for the selected grade and temperature interval. This approximation does not predict irreversible demagnetization, coercivity or a safe operating temperature.
How to read total indicator variation
Total indicator variation is the difference between the largest and smallest indicator readings for the specified setup.
Assumed maximum
+0.012 mmAssumed minimum
−0.008 mmCalculated difference
0.020 mm
+0.012 mmAssumed minimum
−0.008 mmCalculated difference
0.020 mm
An arithmetic example, not a rotor tolerance or inspection result. Specify the datum, measured surface, indicator direction and rotation setup on the drawing.
ENGINEER THE INTERFACES
The Magnet Is Part of a System.
Define the mechanical, magnetic and environmental boundary together.
Motion & Positioning
- Magnetic
- Material, pole arrangement, working gap
- Mechanical
- Shaft datums, fits, retention, envelope
- Verification
- Agreed field, geometry and assembly checks
Torque Across a Boundary
- Magnetic
- Magnet arrangement and effective gap
- Mechanical
- Drive interfaces, alignment, sleeve geometry
- Duty
- Torque, speed, pressure and temperature
FROM REFERENCE TO RELEASE
A Clear Specification Comes First.
Reference data supports material selection. The supplied part is defined by its agreed drawing, material requirements and inspection plan.
Discuss Your ComponentTECHNICAL BASIS
Sources & Scope.
General definitions and methods below support this reference. Third-party publications do not certify Empire products.
- NIST · Units for Magnetic PropertiesSI and cgs magnetic units. The energy-product conversion follows from the listed B and H factors.
- Arnold Magnetic Technologies · Magnetic Properties & Measuring TechniquesDefinitions of remanence, coercivity, energy product and temperature coefficients; pages 4–5 and 8.
- Arnold Magnetic Technologies · Reversible Temperature CoefficientsLinear estimates and the importance of the stated temperature interval. No third-party grade rating is assigned to an Empire product.
- Mitutoyo · Quick Guide to Precision Measuring InstrumentsIndicator-reading range and measurement setup. The runout example uses assumed readings.
Reference edition 2026.09 · Published 27 September 2026