N35 vs N52 Magnets: Strength, Geometry and Temperature

What N35 and N52 actually identify

N35 and N52 are NdFeB grade-family labels associated with nominal material-property ranges under defined test conditions. The higher N-number indicates a higher maximum-energy-product class. It does not define one exact recipe, coercivity class, application temperature, coating, tolerance, price, availability, or finished magnetic result.

Use the Neodymium Magnet Grades guide for the broader naming system. Use the exact approved material data for the proposed production route before making a drawing or release decision.

Engineering Evidence · EM-MAG-05 · Revision A

N35-to-N52 decision boundary

A controlled N52 proposal needs four links: the useful product result that must improve, the circuit constraint preventing a lower-risk geometry solution, adequate coercivity and temperature margin for the exact N52 family, and representative evidence that the change produces a measurable system benefit.

Decision gate	N35 remains a valid choice when	N52 may be considered when	Release evidence
Product target	The current design meets the defined result with margin	The useful result is short and the envelope is constrained	Same measurement position, temperature, assembly state, and acceptance rule
Circuit and geometry	Air gap, return path, leakage, steel, or dimensions offer a lower-risk improvement	Geometry is fixed and analysis shows useful additional material potential	Reviewed drawing, model assumptions, and tolerances
Operating margin	The selected coercivity family survives normal and adverse cases	The exact N52 coercivity family also retains the required margin	Approved curves, load line, peak temperature, reverse field, and loss criterion
Production and supply	Cost, availability, process stability, and repeat supply favor the current route	Measured benefit justifies qualification and supply implications	Samples, inspection, change control, and commercial comparison
Validation	Existing evidence represents the final circuit and duty	Representative tests confirm the predicted product improvement	Prototype or correlated application result and release decision

Use: screening a grade-upgrade request before quotation, prototype, or change release.

Limit: the card contains no universal force multiplier, temperature, price, availability, or winner.

Prepared by: Materials Engineering Team.

Technical review by: Quality & Manufacturing Validation Team.

Download the NdFeB Grade Selection Guide (PDF)

N35 and N52 compared as engineering choices

Why a same-size comparison can mislead

A same-size N52 magnet can produce a stronger result than N35 in a suitable circuit, but the gain is not a fixed percentage. Force and torque respond nonlinearly to air gap, pole area, return steel, saturation, leakage, magnet length, measurement distance, and the operating point.

A higher material class can also deliver little useful gain if the steel is already saturated, the air gap dominates, the field is measured too far from the working region, or another circuit element is the real constraint.

Temperature suffix and coercivity are separate decisions

The N-number is not a maximum operating-temperature rating. Review the exact coercivity family, demagnetization curve and operating point, continuous and peak temperature, dwell time, geometry, opposing field, assembly heating, and allowable irreversible loss.

An N35 family with a more suitable coercivity and thermal margin can be the more robust engineering choice. An N52 family is valid only when its exact property set and supply route meet the same controlled requirements.

A controlled selection sequence

1. Define the useful magnetic result, position, temperature, assembly state, and acceptance rule.
2. Record the magnet envelope, air gap, return path, surrounding steel, tolerances, and leakage paths.
3. Check whether geometry or circuit changes can meet the target with lower technical and supply risk.
4. Compare the exact N35 and N52 coercivity families using approved material data and the same curve convention.
5. Review normal and adverse operating points, including peak temperature and opposing fields.
6. Include coating, magnetization, assembly sequence, inspection, availability, cost, and change control.
7. Validate representative parts or assemblies and release the change against the defined product result.

Information to include in an N35-to-N52 review

• Current grade designation, source, drawing revision, geometry, coating, and magnetization.
• Target field, force, torque, flux, waveform, or sensing result with its measurement method.
• Magnetic circuit, air gap, steel, mechanical interfaces, and assembly state.
• Continuous, peak, assembly, storage, and fault temperatures and dwell times.
• External opposing fields and permitted irreversible change.
• Prototype quantity, annual demand, qualification evidence, and change-control expectations.

Review custom sintered NdFeB magnets, the engineering and DFM process, and the quality and inspection approach. Send the actual circuit and target through the RFQ form when a controlled grade recommendation is needed.

Boundary: exact properties must come from the approved material and production-route data. Finished performance, feasibility, price, MOQ, lead time, and supply choice require the actual drawing, quantity, circuit, operating envelope, and validation plan.