Thin-wall Samarium Cobalt ring magnets are engineered for high-temperature and demagnetization-resistant applications where radial space is severely restricted. Fabricated from rare-earth SmCo5 and Sm2Co17 alloys, these magnets maintain stable magnetic output up to 350°C with a low temperature coefficient of remanence (~ -0.03%/°C).
Due to the brittle nature of sintered SmCo, producing ring geometries with wall thicknesses below 1.5 mm requires specialized multi-axis wire EDM, internal diamond grinding, and controlled magnetic alignment during pressing to prevent micro-cracking and edge chipping. Jiuyi Machine produces these components directly to print specifications for aerospace, defense, and high-speed motor assemblies.
Technical Specifications
|
Parameter |
SmCo1:5 Grade (e.g., YXG-16 to 24) |
SmCo2:17 Grade (e.g., YXG-28 to 33H) |
|
Residual Induction (Br) |
8.2 - 10.5 kGs (0.82 - 1.05 T) |
10.5 - 12.5 kGs (1.05 - 1.25 T) |
|
Coercivity (Hcb) |
>= 7.5 kOe (597 kA/m) |
>= 9.5 kOe (756 kA/m) |
|
Intrinsic Coercivity (Hci) |
>= 15.0 kOe (1194 kA/m) |
>= 25.0 kOe (1989 kA/m) |
|
Max. Energy Product ((BH)max) |
16 - 24 MGOe (128 - 191 kJ/m3) |
28 - 33 MGOe (223 - 263 kJ/m3) |
|
Max. Operating Temperature |
250°C |
350°C |
|
Density |
~ 8.3 - 8.4 g/cm3 |
~ 8.4 - 8.5 g/cm3 |
|
Min. Wall Thickness Capability |
0.8 mm |
0.5 mm (depending on OD/ID ratio) |
|
Standard Dimensional Tolerance |
+/- 0.03 mm (Ground) |
+/- 0.01 mm (Precision Ground) |
Key Features
Operates continuously up to 350°C without significant irreversible flux loss, outperforming NdFeB alternatives in high-temperature environments.
Contains no iron in SmCo5 and minimal free iron phase in Sm2Co17, eliminating the mandatory protective plating required for NdFeB in standard operational environments.
Specialized CNC internal/external diamond grinding and wire-cut electrical discharge machining (EDM) achieve wall thicknesses down to 0.5 mm with structural integrity.
High intrinsic coercive force (Hci) prevents degradation under opposing magnetic fields and heavy mechanical vibration.
Applications
High-Speed Rotor Assemblies: Inner and outer rotor retention rings for aerospace brushless motors operating above 50,000 RPM.
Microwave Tubes: Focusing and confinement magnetic structures in traveling-wave tubes (TWT) and klystrons.
Magnetic Couplings: Hermetically sealed pump drives transmitting torque through containment shells at elevated temperatures.
Precision Sensors: Stator and rotor rings for angular encoders and synchros requiring stable output across fluctuating ambient temperatures.
Customization
Manufacturing parameters are adjusted according to specific engineering requirements:
Dimensions:
Outer Diameter (OD) up to 150 mm, Inner Diameter (ID) down to 3 mm, and Length/Height up to 50 mm.
Magnetic Orientation:
Anisotropic field alignment during powder compaction for directional flux concentration (Radial multi-pole magnetization requires specialized yokes).
Surface Treatment:
Uncoated (standard passivated finish), Nickel (Ni-Cu-Ni) plating, or Parylene coating for particle containment in high-vacuum applications.
Tolerances:
Ground surfaces held to +/- 0.01 mm for direct press-fit assembly.
Manufacturing & Quality Control
Production follows a strict powder metallurgy workflow:
• Raw Material Melting & Alloying: Vacuum induction melting of high-purity Samarium, Cobalt, Iron, Copper, and Zirconium raw materials.
• Jet Milling: Closed-loop inert gas milling producing fine powders with a controlled particle size distribution (D50 = 3 - 5 um).
• Magnetic Alignment & Pressing: Isostatic pressing under an aligned magnetic field of 20+ kOe to maximize anisotropic orientation.
• Sintering & Solution Treatment: Liquid-phase sintering in a high-purity vacuum furnace followed by precise thermal aging.
• Machining & Grinding: Diamond wheel internal/external grinding and wire EDM performed under liquid coolant to prevent micro-fracturing of the brittle matrix.
Inspection & Testing:
• Hysteresis Graph Testing: 100% sample testing using a Hysteresis Graph to verify Br, Hcb, and (BH)max at room temperature and elevated temperatures up to 200°C.
• Dimensional Metrology: 3D optical comparators and air gauging for concentricity, wall thickness uniformity, and ID/OD tolerances.
• Visual Surface Inspection: 20X magnification screening to detect edge chipping, micro-cracks, and surface voids.
Packaging & Documentation
Packaging: Magnetically shielded individual compartments with non-ferrous spacer blocks to prevent transit damage and snap-fractures between thin-walled rings. Outer export-grade wooden crates lined with high-density EVA foam. Meets international air and ocean freight magnetic field safety limits (IATA Packing Instruction 953).
Documentation Provided with Shipment:
Material Test Report (MTR): Including lot-specific magnetic properties (Br, Hcb, Hci, (BH)max).
Dimensional Inspection Report: CMM data for sampled parts.
Certificate of Conformity (CoC): Referencing raw material heat numbers and ISO 9001 quality management standards.
FAQ
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