Grade Selection
Balance remanence, intrinsic coercivity, temperature, magnetic circuit and cost. Chinese Y and American C grades are listed below.
Ring Ferrite Magnets
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Ningbo Vanguard Technologies Co., Ltd
Cost-effective ceramic ring magnets for motors, speakers, sensors, meters and industrial magnetic assemblies.
Vanguard supports grade selection, ring geometry, magnetization planning, sample development and production supply. OD, ID, axial length, wall thickness, pole configuration and magnetic circuit are reviewed together.
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Selection Snapshot
Balance remanence, intrinsic coercivity, temperature, magnetic circuit and cost. Chinese Y and American C grades are listed below.
Specify OD, ID, axial length, wall thickness, chamfers, roundness and concentric relationships.
Define axial, radial, diametrical or multipole magnetization with a polarity sketch and inspection method.
Request bare rings, polarity-sorted sets, bonded components or rotor assembly support after feasibility review.
Geometry & Magnetization
State OD, ID, axial length, chamfers and datum relationships. Thin walls, large diameter ratios and interrupted features need tooling and strength review.
A ring can be axially, radially, diametrically or multipole magnetized where orientation and fixture design permit. Provide the required pole count and sequence.
Engineering Selection
Review bore size, wall thickness, axial length and chamfers as one geometry. Avoid sharp internal edge loading and provide assembly clearance appropriate to brittle ferrite.
Field distribution depends on grade, material orientation, magnetization, pole count, steel circuit and working gap. A ring shape alone does not guarantee a uniform field.
Do not assume a press fit is suitable. Define clearance, adhesive, carrier support, cure process and any retaining feature so radial stress does not crack the ring.
For rotating assemblies, review concentricity, balance, retention, speed, temperature and bonded-joint validation at the rotor level.
Magnetic Performance
Reference values at 20 °C from the existing Vanguard ferrite grade table. The approved material specification and agreed inspection criteria govern each order.
| Grade | Standard | Br mT | Br kG | Hcb kA/m | Hcb kOe | Hcj kA/m | Hcj kOe | BHmax kJ/m³ | BHmax MGOe |
|---|---|---|---|---|---|---|---|---|---|
| Y8T | Chinese | 200-235 | 2.0-2.35 | 125-160 | 1.57-2.01 | 210-280 | 2.64-3.52 | 6.5-9.5 | 0.8-1.2 |
| Y10T | Chinese | 200-235 | 2.0-2.35 | 128-160 | 1.61-2.01 | 210-280 | 2.64-3.52 | 6.4-9.6 | 0.8-1.2 |
| Y20 | Chinese | 320-380 | 3.2-3.8 | 135-190 | 1.70-2.39 | 140-195 | 1.76-2.45 | 18.0-22.0 | 2.3-2.8 |
| Y22H | Chinese | 310-360 | 3.1-3.6 | 220-250 | 2.76-3.14 | 280-320 | 3.52-4.02 | 20.0-24.0 | 2.5-3.0 |
| Y23 | Chinese | 320-370 | 3.2-3.7 | 170-190 | 2.14-2.39 | 190-230 | 2.39-2.89 | 20.0-25.5 | 2.5-3.2 |
| Y25 | Chinese | 360-400 | 3.6-4.0 | 135-170 | 1.70-2.14 | 140-200 | 1.76-2.51 | 22.5-28.0 | 2.8-3.5 |
| Y26H | Chinese | 360-390 | 3.6-3.9 | 220-250 | 2.76-3.14 | 225-255 | 2.83-3.20 | 23.0-28.0 | 2.9-3.5 |
| Y26H-1 | Chinese | 360-390 | 3.6-3.9 | 200-250 | 2.51-3.14 | 225-255 | 2.83-3.20 | 23.0-28.0 | 2.9-3.5 |
| Y26H-2 | Chinese | 360-380 | 3.6-3.8 | 263-288 | 3.30-3.62 | 318-350 | 4.00-4.40 | 24.0-28.0 | 3.0-3.5 |
| Y27H | Chinese | 370-400 | 3.7-4.0 | 205-250 | 2.58-3.14 | 210-255 | 2.64-3.20 | 25.0-29.0 | 3.1-3.6 |
| Y28 | Chinese | 370-400 | 3.7-4.0 | 175-210 | 2.20-2.64 | 180-220 | 2.26-2.76 | 26.0-30.0 | 3.3-3.8 |
| Y28H-1 | Chinese | 380-400 | 3.8-4.0 | 240-260 | 3.02-3.27 | 250-280 | 3.14-3.52 | 27.0-30.0 | 3.4-3.8 |
| Y28H-2 | Chinese | 360-380 | 3.3-3.8 | 271-295 | 3.41-3.71 | 382-405 | 4.80-5.09 | 26.0-30.0 | 3.3-3.8 |
| Y30 | Chinese | 370-400 | 3.7-4.0 | 175-210 | 2.20-2.64 | 180-220 | 2.26-2.76 | 26.0-30.0 | 3.3-3.8 |
| Y30BH | Chinese | 380-390 | 3.8-3.9 | 223-235 | 2.80-2.95 | 231-245 | 2.90-3.08 | 27.0-30.0 | 3.4-3.8 |
| Y30H-1 | Chinese | 380-400 | 3.8-4.0 | 230-275 | 2.89-3.46 | 235-290 | 2.95-3.64 | 27.0-32.0 | 3.4-4.0 |
| Y30H-2 | Chinese | 395-415 | 3.95-4.15 | 275-300 | 3.46-3.77 | 310-335 | 3.90-4.21 | 27.0-32.5 | 3.4-4.1 |
| Y32 | Chinese | 400-420 | 4.0-4.2 | 160-190 | 2.01-2.39 | 165-195 | 2.07-2.45 | 30.0-33.5 | 3.8-4.2 |
| Y32H-1 | Chinese | 400-420 | 4.0-4.2 | 190-230 | 2.39-2.89 | 230-250 | 2.89-3.14 | 31.5-35.0 | 4.0-4.4 |
| Y32H-2 | Chinese | 400-440 | 4.0-4.4 | 224-240 | 2.81-3.02 | 230-250 | 2.89-3.14 | 31.0-34.0 | 3.9-4.3 |
| Y33 | Chinese | 410-430 | 4.1-4.3 | 220-250 | 2.76-3.14 | 225-255 | 2.83-3.20 | 31.5-35.0 | 4.0-4.4 |
| Y33H | Chinese | 410-430 | 4.1-4.3 | 250-270 | 3.14-3.39 | 250-275 | 3.14-3.46 | 31.5-35.0 | 4.0-4.4 |
| Y34 | Chinese | 420-440 | 4.2-4.4 | 200-230 | 2.51-2.89 | 205-235 | 2.58-2.95 | 32.5-36.0 | 4.1-4.5 |
| Y35 | Chinese | 430-450 | 4.3-4.5 | 215-239 | 2.70-3.00 | 217-241 | 2.73-3.03 | 33.1-38.2 | 4.2-4.8 |
| Y36 | Chinese | 430-450 | 4.3-4.5 | 247-271 | 3.10-3.41 | 250-274 | 3.14-3.44 | 35.1-38.3 | 4.4-4.8 |
| Y38 | Chinese | 440-460 | 4.4-4.6 | 285-305 | 3.58-3.83 | 294-310 | 3.69-3.90 | 36.6-40.6 | 4.6-5.1 |
| Y40 | Chinese | 440-460 | 4.4-4.6 | 330-354 | 4.15-4.45 | 340-360 | 4.27-4.52 | 37.5-41.8 | 4.7-5.3 |
| C1 | American | 230 | 2.3 | 148 | 1.86 | 258 | 3.5 | 8.36 | 1.05 |
| C5 | American | 380 | 3.8 | 191 | 2.4 | 199 | 2.5 | 27 | 3.4 |
| C7 | American | 340 | 3.4 | 258 | 3.23 | 318 | 4.0 | 21.9 | 2.75 |
| C8 / C8A | American | 385 | 3.85 | 235 | 2.95 | 242 | 3.05 | 27.8 | 3.5 |
| C8B | American | 420 | 4.2 | 232 | 2.913 | 236 | 2.96 | 32.8 | 4.12 |
| C9 | American | 380 | 3.8 | 280 | 3.516 | 320 | 4.01 | 26.4 | 3.32 |
| C10 | American | 400 | 4.0 | 280 | 3.52 | 284 | 3.57 | 30.4 | 3.82 |
| C11 | American | 430 | 4.3 | 200 | 2.512 | 204 | 2.56 | 34.4 | 4.32 |
| C12 | American | 400 | 4.0 | 290 | 3.65 | 318 | 4.0 | 32 | 4.0 |
Grade selection: Compare values only under equivalent test conditions. Final performance also depends on material orientation, segment geometry, magnetization, motor air gap and the measurement method.
Material Reference
General reference values for sintered ferrite materials. These values describe the material family and are not part-specific acceptance limits unless separately agreed.
| Parameter | Unit | Typical Value |
|---|---|---|
| Density / ρ | g/cm³ | 4.9-5.1 |
| Vickers Hardness / HV | - | 400-700 |
| Compression Strength | N/mm² | 680-720 |
| Coefficient of Thermal Expansion / α | 10-6/°C | C⊥: 10; C∥: 15 |
| Electrical Resistivity / ρ | mΩ·cm | 1 × 1010 |
| Thermal Conductivity / k | W/(cm·°C) | 0.029 |
| Tensile Strength / σ | Pa | 34 × 106 |
| Modulus of Elasticity / λ | Pa | 1.8 × 1011 |
| Flexural Strength / σ | Pa | 62 × 106 |
| Compression Strength | Pa | 895 × 106 |
| Poisson's Ratio / ν | - | 0.28 |
Orientation notation: C∥ and C⊥ indicate directions parallel and perpendicular to the material orientation axis. Confirm test methods when a physical property is used as a design or acceptance requirement.
Drawing Definition
The ranges below are catalogue references from the existing page. OD, ID and axial length cannot be selected independently; tooling, wall thickness, grade, material orientation and grinding route are reviewed together.
| Dimension | Reference Minimum | Reference Maximum | Drawing Requirement |
|---|---|---|---|
| Outer Diameter (OD) | 3 mm | 300 mm | Define roundness and external datum |
| Inner Diameter (ID) | 1 mm | 140 mm | Define fit, bore finish and concentric relationship |
| Axial Length (L) | 1 mm | 80 mm | Define face parallelism and edge condition |
| Wall Thickness | Calculated from (OD-ID)/2 | Review strength, tooling and magnetization together | |
Final tolerances are quoted by feature after geometry, tooling, grinding stock and inspection access are reviewed. Countersinks, slots, segmented rings and thin-wall designs require separate feasibility confirmation.
Custom Features
| Area | Options for Review | Engineering Focus |
|---|---|---|
| Geometry | Ring, washer, tube, thin ring, thick wall, countersink, slot and segmented ring | Tooling, wall strength, bore grinding and edge integrity |
| Magnetization | Axial, radial, diametrical, multipole, matched set and fixture-specific pattern | Material orientation, pole count, waveform and fixture feasibility |
| Finishing | ID/OD grinding, face grinding, chamfering, cleaning, marking and housing | Final fit, assembly cleanliness and brittle-edge protection |
| Inspection | Grade properties, surface flux, pole distribution, dimensions and runout | Defined fixture, measurement radius, gap and acceptance limits |
Application Fit
Coordinate shaft or carrier fit, pole pattern, air gap, speed, retention and temperature for the complete rotating assembly.
Review ring dimensions, steel plates, voice-coil gap and magnetic circuit geometry rather than selecting the magnet by grade alone.
Define pole count, waveform, working distance, angular reference and measurement setup for repeatable sensing.
Use ferrite rings where stable supply, corrosion resistance and cost are important, while validating the final product requirements.
Production Support
Align powder preparation, material orientation, pressing and sintering with the approved grade and ring geometry.
Inspect bore, outside diameter, axial length, wall thickness, roundness, concentricity, parallelism and agreed chip limits.
Confirm polarity, grade properties, surface flux or pole distribution under an agreed fixture and scan path.
Define polarity marking, set sorting, lot identification, reports and packaging that protects brittle rings.
Project Workflow
Technical Questions
No. Axial magnetization is common, but radial, diametrical and multipole patterns may be possible depending on material orientation, geometry and magnetizing fixture.
Ferrite is brittle and direct interference can create damaging hoop stress. Use a reviewed clearance, adhesive, carrier or retention design instead of assuming a metal-like press fit.
Define pole count, pole sequence, angular reference, scan radius, probe distance, waveform or minimum pole values, and the measurement fixture.
Ferrite generally has good corrosion resistance and is often uncoated. Marking, coating or housing may still be used for cleanliness, identification, bonding or project-specific exposure.
Yes, rotor projects can be reviewed. Include the shaft, carrier, adhesive, retention, balancing, speed, temperature and inspection requirements.
Geometry, tooling, grade, orientation, magnetizing fixture, inspection and quantity determine the quotation. Share sample demand and annual forecast for review.
Send the drawing and application conditions for a ring ferrite magnet review.
