Magnet Technology

Operating from raw material selection to advanced powder metallurgy, multi-pole magnetization, and tight-tolerance CNC machining, we translate engineering drawings into reliable production components. Our manufacturing processes comply with strict international standards (IEC, ASTM, ISO 9001, IATF 16949), ensuring batch-to-batch magnetic consistency, thermal stability, and long-term corrosion resistance for mission-critical applications.

Magnet Materials

Selecting the correct permanent magnet material dictates electromagnetic efficiency, thermal threshold, and mechanical integrity. Five primary material families serve distinct operational environments:

Neodymium Iron Boron (NdFeB / N-Series & H/SH/UH Grades): Delivers maximum energy product ((BH)max up to 55 MGOe) for space-constrained high-field density applications like servo motors. Standard grades operate up to 80 degrees C; heavy rare-earth diffusion (HRE) grades extend limits to 220 degrees C.

Samarium Cobalt (SmCo / 1:5 & 2:17 Alloys): Engineered for high-temperature stability up to 350 degrees C with minimal flux loss (Br temperature coefficient approx. -0.03%/deg C) and high oxidation resistance without protective plating.

Alnico (Cast & Sintered): Features exceptional thermal stability (Br variation approx. -0.02%/deg C) and mechanical impact resistance for measuring instruments and high-temperature sensor probes.

Hard Ferrite / Ceramic (S8 / Y30H-2 / C8): Cost-optimized, chemically inert solution operating up to 250 degrees C for fractional horsepower DC motors and magnetic separators.

Bonded NdFeB: Combines magnetic powder with polymer binders via injection or compression molding, enabling multi-pole patterns and net-shape tolerances without secondary machining.

Magnet Grades & Magnetic Performance

Performance metrics comply with IEC 60404-8-1 and ASTM A977 standards:

Material Family	Grade Range	Residual Induction (Br)	Coercivity (Hci)	Max. Operating Temp. (Tmax)
Sintered NdFeB	N35 – N52	11.7 - 14.8 kGs	>= 12 kOe	80 degrees C
High-Temp NdFeB	35H – 52H	11.7 - 14.5 kGs	>= 17 kOe	120 degrees C
High-Temp NdFeB	35SH – 48SH	11.7 - 14.2 kGs	>= 20 kOe	150 degrees C
High-Temp NdFeB	33UH – 42UH	11.4 - 13.5 kGs	>= 25 kOe	180 degrees C
Samarium Cobalt	2:17 (Sm2Co17)	10.0 - 11.8 kGs	>= 30 kOe	350 degrees C
Hard Ferrite	Y30H / C8	3.8 - 4.1 kGs	>= 3.2 kOe	250 degrees C

Demagnetization Curves (J-H and B-H): Hysteresis graph testing at ambient and elevated temperatures verifies knee-point stability and prevents load-induced flux collapse.

Magnetization Technology

Magnetic vector orientation controls flux interaction with steel paths and coils:

Axial & Diametral:

Standard orientation through thickness or across diameter.

Multi-Pole Ring:

Helmholtz coil fixtures generate custom pole configurations (4 to 64 poles) on ring magnets for brushless DC rotors.

Radial:

Outward or inward radial flux paths executed via capacitor-discharge pulse magnetizers up to 3000V.

Skewed & Halbach Arrays:

Custom yoke configurations that concentrate flux unidirectionally or utilize skewed pole patterns to minimize motor noise and vibration.

Magnet Shapes & Precision Machining

Sintered rare-earth materials match ceramic hardness (HVS 600–800), requiring diamond-tool CNC processing:

Geometries: Blocks, discs, cylinders, rings, wedges, and segmented arc stators.

Tolerances: Standard dimensional control at +/- 0.05 mm; high-precision grinding achieves +/- 0.01 mm for outer/inner diameters and parallelism.

Micro-Machining: Multi-axis wire EDM and ID diamond core drilling produce micro-pellets and thin-wall rings down to 0.5 mm without edge chipping.

Surface Treatment & Coating

Unprotected NdFeB requires barrier coatings to prevent rapid oxidation and corrosion:
Metallic Platings:

01/

Ni-Cu-Ni: Standard galvanic layer (15-25 um); tested to >= 48 hours Salt Spray (ASTM B117).

02/

Epoxy Electrodeposition: Uniform polymer layer (10-30 um) for saline/chemical resistance; passes >= 96 hours salt spray.

03/

Zinc (Zn): Sacrificial coating for mild environments.

04/

Gold / Silver / Tin: Specialized barrier layers for medical implants or contact resistance reduction.

05/

Conversion Coatings: Passivation and phosphating for SmCo and Ferrite assembly dusting prevention.

06/

PCT Testing: Batch validation at 121 degrees C, 2 atm, 100% RH for 24-96 hours to verify coating adhesion.

Magnet Manufacturing Technology

Powder metallurgy processes drive structural densification:

Alloy Preparation:

Vacuum induction melting followed by hydrogen decrepitation (HD) into coarse powder.

Jet Milling:

Controlled particle size reduction (3-5 um) under an inert nitrogen atmosphere.

Magnetic Field Pressing:

Alignment and compaction via magnetic presses (up to 2.0 T) to maximize remanence (Br).

Vacuum Sintering:

Multi-zone vacuum furnaces with argon partial-pressure control achieve density > 99.5%.

CNC Machining & Coating:

Hard-material grinding followed by galvanic/PVD application and thermal curing.

Pulse Magnetization:

Final flux activation via capacitor discharge systems.

Quality Control & Testing

Traceability and testing are integrated across checkpoints:

Hysteresis Measurement:

Permeameter testing measures Br, Hci, and (BH)max across temperature ranges.

Helmholtz Coil Testing:

Verifies total magnetic flux output and angle deviation against CAD files (+/- 1% tolerance).

3D CMM Inspection:

Non-contact optical and coordinate measuring machines verify GD&T and concentricity.

Environmental Chamber Testing:

Thermal shock testing from -40 degrees C to +200 degrees C with humidity cycling.

Magnet Design & Engineering Support

FEA Magnetic Simulation: 3D finite element analysis (Ansys Maxwell / FEMM) models flux paths, demagnetization risks, and forces prior to tooling.

Tolerance Stack-Up: Evaluates air gaps, thermal expansion differentials, and bondline thicknesses.

Rapid Prototyping: Dedicated sample lines ensuring standard delivery within 7 to 10 working days.

Magnet Application Technology

Permanent Magnet Synchronous Motors (PMSM):

Embedded high-coercivity rotor blocks resisting armature reaction fields.

Magnetic Couplings:

Hermetically sealed inner/outer rotors transmitting torque across barriers without shaft seals.

Magnetic Separation:

High-gradient separators (HGMS) extracting ferrous contaminants from fluid or powder streams.

Linear Encoders:

Alternating pole-pitch scales with sub-micron positional accuracy.

Custom Magnet Development

Requirement Intake:

Review load profiles, spatial limits, temperatures, and exposure limits.

Feasibility & Simulation:

Generate magnetic circuit models and grade recommendations.

Prototyping & Validation:

Produce initial samples via wire EDM for bench testing.

Pilot Run & PPAP Submission:

Small-batch delivery with FMEA, dimensional reports, and material certs.

Technical Documentation

Requirement Intake:

Review load profiles, spatial limits, temperatures, and exposure limits.

Feasibility & Simulation:

Generate magnetic circuit models and grade recommendations.

Prototyping & Validation:

Produce initial samples via wire EDM for bench testing.

Pilot Run & PPAP Submission:

Small-batch delivery with FMEA, dimensional reports, and material certs.

FAQ

Q: How do I prevent permanent demagnetization in high-temperature motors?

A: Select an NdFeB grade whose intrinsic coercivity (Hci) exceeds the demagnetizing field at peak operating temperature (e.g., grades with Hci >= 25 kOe like 38UH operate up to 180 degrees C).

Q: What is the difference between open-circuit and closed-circuit testing?

A: Open-circuit measures individual shapes influenced by self-demagnetization fields; closed-circuit uses a hysteresis graph or iron yoke to eliminate air gaps and isolate true intrinsic material properties.

Q: Can rare-earth magnets be machined after plating?

A: No. Machining must precede plating. Cutting a plated magnet exposes raw material, destroying the corrosion barrier and triggering oxidation.

Q: What adhesive bonds magnets into steel housings?

A: High-strength modified structural epoxies or acrylics. Surfaces require solvent degreasing and mechanical abrasion or priming to ensure shear strength.