In This Article
Key Takeaways
- ◆The numeric grade denotes a nominal energy-product class; the suffix identifies a coercivity/temperature class.
- ◆The permissible duty depends on working point, reverse field, geometry and the actual material curves.
- ◆A suffix does not prescribe a fixed Dy or Tb content.
- ◆Reversible thermal loss can recover on cooling. Irreversible demagnetization can sometimes be restored by remagnetization if the material remains intact; structural degradation may be permanent. Exceeding a nominal operating rating does not alone prove microstructural destruction. Magnequench’s technical FAQ distinguishes these losses. Evaluate the cause and test the part before reuse; this is not a field-repair guarantee.
- ◆Mainrich’s sintered NdFeB range is N30 to N56, with no AH grades. The top grade depends on the temperature series: N56, N54M, N52H, N52SH, N50UH and N45EH. Grades up to N52SH can be made without a Chinese export licence, so we offer those first; UH and EH grades need a licence, applied for per order. Confirm the grade, suffix, geometry and production route for each drawing. This summary does not offer every combination; grades outside it in educational examples are not Mainrich supply offers.
Read the grade name
An NdFeB designation combines a nominal maximum-energy-product class with a suffix used for coercivity and temperature classification. The exact guaranteed property window belongs to the supplier’s material specification. Educational examples such as N52 illustrate nomenclature; they are not an offer to supply that grade.
Mainrich’s sintered NdFeB range is N30 to N56, with no AH grades. The top grade depends on the temperature series: N56, N54M, N52H, N52SH, N50UH and N45EH. Grades up to N52SH can be made without a Chinese export licence, so we offer those first; UH and EH grades need a licence, applied for per order.
Confirm the grade, suffix, geometry and production route for each drawing. This summary does not offer every combination; grades outside it in educational examples are not Mainrich supply offers.
Compare energy product and hot performance
Select the grade using the actual hot demagnetization curves, the magnetic circuit working point and the worst opposing field. A suffix is a nominal material class, not a guaranteed motor temperature limit or a chemical recipe. Compare Br and Hcj together. A higher energy-product number alone cannot determine which magnet will deliver the required hot field.
Check the specified properties
Alloy composition, grain structure, orientation and processing determine the magnetic properties. Different routes can reach a coercivity class, so the suffix does not reveal a fixed heavy-rare-earth percentage. Reversible thermal loss can recover on cooling. Irreversible demagnetization can sometimes be restored by remagnetization if the material remains intact; structural degradation may be permanent.
Exceeding a nominal operating rating does not alone prove microstructural destruction. Magnequench’s technical FAQ distinguishes these losses. Evaluate the cause and test the part before reuse; this is not a field-repair guarantee.
Assess a diffusion candidate
The reported N45H magnetic comparison and the separate historical 50H Dy-reduction example have different scopes. See the GBD evidence and limitations. Finished-part savings require a quotation and qualification of the proposed route.
Specify the application requirements
Specify the maximum magnet temperature and the worst opposing field, then evaluate the operating point on the hot curves. Agree an acceptable irreversible loss and a qualification test. A generic temperature margin or automatic suffix upgrade is not sufficient.
Confirm the specific supply route
Motor and sensor requirements depend on the circuit. Compare grades within the available geometry and duty using measured curves and the assembly model. Permanent-magnet MRI examples refer to a scanner’s main-field design where that architecture is used; they do not refer to gradient coils.
What to ask your supplier
Ask for guaranteed Br, Hcj and BHmax limits, hot curves, measurement conditions, lot traceability and change control. Check the current certificate for the actual manufacturing entity, address and activity. Agree PPAP level and required reports for the order; a network relationship does not certify every plant or assembly.
Frequently Asked Questions
What does N52 mean?
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It is a nominal energy-product grade designation used in technical education. Read the manufacturer’s actual property limits and curves. Mainrich’s sintered NdFeB range is N30 to N56, with no AH grades. The top grade depends on the temperature series: N56, N54M, N52H, N52SH, N50UH and N45EH. Grades up to N52SH can be made without a Chinese export licence, so we offer those first; UH and EH grades need a licence, applied for per order. Confirm the grade, suffix, geometry and production route for each drawing. This summary does not offer every combination; grades outside it in educational examples are not Mainrich supply offers.
What changes between suffixes?
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Select the grade using the actual hot demagnetization curves, the magnetic circuit working point and the worst opposing field. A suffix is a nominal material class, not a guaranteed motor temperature limit or a chemical recipe. Mainrich’s sintered NdFeB range is N30 to N56, with no AH grades. The top grade depends on the temperature series: N56, N54M, N52H, N52SH, N50UH and N45EH. Grades up to N52SH can be made without a Chinese export licence, so we offer those first; UH and EH grades need a licence, applied for per order. Confirm the grade, suffix, geometry and production route for each drawing. This summary does not offer every combination; grades outside it in educational examples are not Mainrich supply offers.
Can a demagnetized magnet be remagnetized?
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Reversible thermal loss can recover on cooling. Irreversible demagnetization can sometimes be restored by remagnetization if the material remains intact; structural degradation may be permanent. Exceeding a nominal operating rating does not alone prove microstructural destruction. Magnequench’s technical FAQ distinguishes these losses. Evaluate the cause and test the part before reuse; this is not a field-repair guarantee.
Does GBD always make a magnet cheaper?
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The reported N45H magnetic comparison and the separate historical 50H Dy-reduction example have different scopes. See the GBD evidence and limitations. Finished-part savings require a quotation and qualification of the proposed route.
How do I select a grade?
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Specify the maximum magnet temperature and the worst opposing field, then evaluate the operating point on the hot curves. Agree an acceptable irreversible loss and a qualification test. A generic temperature margin or automatic suffix upgrade is not sufficient.
Send the drawing, operating temperature and required field for a material and supply review.
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