Inspection Plan Agreement
Specify critical characteristics, sampling and acceptance criteria so the requested records match your part and application.
Plan the quality reviewCast & Sintered AlNiCo Magnets
Cast and sintered AlNiCo offers low reversible temperature drift for instruments, meters and sensors. Published 450°C+ material references require a grade-specific circuit and stability review; flux is not constant across the full temperature range.
Product Range
AlNiCo Magnets — Product Gallery
Product forms, uses and selection considerations. Final specifications are agreed for each project.
Horseshoes & Blocks
Open-gap geometries with circuit requirements confirmed.
Cast AlNiCo Forms
Cast forms for instruments and magnetic assemblies.
Ring Magnets
Annular parts with defined working-gap requirements.
Rods & Cylinders
Cylindrical forms for pickups and instrument designs.
Specify Geometry & the Working Point
Rods, horseshoes and rings illustrate delivery forms, not interchangeable magnetic circuits. Choose cast or sintered AlNiCo with the required geometry and published properties.
Review the working point, open-circuit handling and opposing fields as well as temperature. Define magnetization and keeper requirements for the instrument or sensor assembly.
Review cast and sintered grades- Working-point and demagnetization requirements
- Magnetic treatment and final magnetization
- Geometry, mounting and temperature stability
SELECTION GUIDEApplication selection notesExplore applications and requirements
Why AlNiCo?
AlNiCo remains useful for instruments and sensors that require low reversible temperature drift, subject to magnetic-circuit and grade review.
- ✓Temperature stability — reversible Br coefficient of -0.01 to -0.02%/°C — low reversible drift; evaluate the accumulated change across the specified temperature range
- ✓High Curie temperature — 850°C — far above any operating environment
- ✓Excellent corrosion resistance — metallic alloy with natural oxidation resistance
- ✓Castable into complex shapes — horseshoes, E-cores, and custom geometries without assembly
Applications
Published reference data. Curie-temperature values in °F are calculated from the retained °C values using °F = 1.8 × °C + 32. Curie temperature is not an operating-temperature limit. Confirm material grade and production route before approval.
For AlNiCo 9, the published Hci pair 1440 Oe / 139 kA/m is not an equivalent-unit pair: 1440 Oe converts to approximately 114.6 kA/m. Confirm the governing source value before using this row for design approval.
| Application | Typical Spec | Why This Material |
|---|---|---|
| Precision Instruments | Alnico 2 / 5 | Stable calibration reference over wide temp range |
| Watt-Hour Meters | Alnico 5 | Decades of drift-free measurement |
| Reed Switch Actuation | Alnico 3 | Reliable actuation from -40°C to 150°C |
| Radar & TWT | Alnico 8 / 9 | Stable fields at extreme temperatures |
| Educational & Scientific | Alnico 2 | Classic red/green painted demonstration magnets |
Cast vs Sintered AlNiCo
Two manufacturing routes with different trade-offs:
- ✓Cast AlNiCo — poured as molten alloy — highest energy product, complex shapes possible, larger grain structure
- ✓Sintered AlNiCo — powder metallurgy — tighter tolerances (±0.05mm vs ±0.2mm), finer grain, better for small parts
- ✓Our recommendation — cast for parts >20g and complex geometries; sintered for small precision parts needing tight tolerance
AlNiCo Design Notes
AlNiCo has low coercivity — design the magnetic circuit carefully:
- ✓Low iHc (600–1600 Oe) — AlNiCo demagnetizes easily; length-to-diameter ratio should be ≥4 for reliable operation
- ✓Magnetically stabilized — we can pre-stabilize AlNiCo magnets by demagnetizing 5–10% after magnetization, to improve stability under the agreed exposure conditions; this does not eliminate all reversible temperature drift
- ✓Magnetization — AlNiCo requires a strong magnetizing field (3–4× iHc) — we can magnetize in-house or supply unmagnetized for your process
- ✓ Machinability — AlNiCo is hard and brittle; grinding or specialist EDM is typically needed. Review holes and detailed features for near-net casting or an approved machining route
- We recommend magnetizing AlNiCo after assembly, in its final magnetic circuit, to preserve the working point.
- Specify storage, assembly sequence and magnetic-circuit conditions so handling does not undermine the intended performance.
Grades & Technical Data
Use this single reference for grade properties, application notes and available datasheets. Confirm the selected specification with engineering before ordering.
Application Selection Notes
| Alloy | Process | Temp. reference* | Typical application |
|---|---|---|---|
| Alnico 2 | Cast | 450°C | General, educational |
| Alnico 5 | Cast | 450°C | Meters, instruments |
| Alnico 5-7 | Cast | 450°C | Premium cast |
| Alnico 8 | Cast | 450°C | High coercivity |
| Alnico 9 | Sintered | 450°C | Small precision parts |
*Temperature values are selection references, not part-specific limits. Confirm the grade, magnetic circuit and test conditions before specifying.
Sintered AlNiCo Grades
| Sintered AlNiCo – Available Grades | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| NEM Grade | Residual Induction Br | Coercive Force Hc | Intrinsic Coercive Force Hci | Maximum Energy Product (BH)max | Max. Operating Temp.* | |||||
| Nominal kG | Nominal T | Nominal Oe | Nominal kA/m | Minimum Oe | Minimum kA/m | Nominal MGOe | Nominal kJ/m³ | Nominal °C | Nominal °F | |
| Alnico 2 | 7.0 | 0.70 | 500 | 40 | 540 | 43 | 1.5 | 12 | 450°C | 840°F |
| Alnico 5 | 11.0 | 1.10 | 600 | 48 | 600 | 48 | 4.25 | 34 | 450°C | 840°F |
| Alnico 8 | 8.8 | 0.88 | 1,530 | 121 | 1,600 | 127 | 5.25 | 42 | 450°C | 840°F |
| * The listed maximum operating temperatures are based on an adequate Length to Diameter ratio or a properly designed magnetic circuit. The listed values are for reference and validation must occur before one chooses a design path. Please consult a Ningbo Empire technical representative before selecting or designing with AlNiCo magnet alloy. | ||||||||||
Cast AlNiCo Grades
| Cast AlNiCo – Available Grades | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| NEM Grade | Residual Induction Br | Coercive Force Hc | Intrinsic Coercive Force Hci | Maximum Energy Product (BH)max | Max. Operating Temp.* | |||||
| Nominal kG | Nominal T | Nominal Oe | Nominal kA/m | Minimum Oe | Minimum kA/m | Nominal MGOe | Nominal kJ/m³ | Nominal °C | Nominal °F | |
| Alnico 5 | 12.2 | 1.22 | 600 | 48 | 630 | 50 | 5.0 | 40 | 500°C | 930°F |
| Alnico 5B | 12.2 | 1.22 | 650 | 52 | 660 | 53 | 5.5 | 44 | 500°C | 930°F |
| Alnico 5 DG | 12.5 | 1.25 | 690 | 55 | 700 | 56 | 6.5 | 52 | 500°C | 930°F |
| Alnico 5-7 | 13.0 | 1.30 | 700 | 56 | 740 | 59 | 7.5 | 60 | 525°C | 980°F |
| Alnico 8-HC | 7.0 | 0.70 | 1,750 | 139 | 1,750 | 139 | 4.5 | 36 | 525°C | 980°F |
| Alnico 8 | 8.2 | 0.82 | 1,500 | 119 | 1,600 | 127 | 5.0 | 40 | 525°C | 980°F |
| Alnico 8B | 8.8 | 0.88 | 1,500 | 119 | 1,650 | 131 | 5.5 | 44 | 525°C | 980°F |
| Alnico 8C | 9.0 | 0.90 | 1,380 | 110 | 1,440 | 115 | 7.5 | 60 | 525°C | 980°F |
| Alnico 9 | 10.5 | 1.05 | 1,410 | 112 | 1,440 | 139 | 9.0 | 72 | 525°C | 980°F |
| * The listed maximum operating temperatures are based on an adequate Length to Diameter ratio or a properly designed magnetic circuit. The listed values are for reference and validation must occur before one chooses a design path. Please consult a Ningbo Empire technical representative before selecting or designing with AlNiCo magnet alloy. | ||||||||||
Reversible Temperature Coefficients
| Reversible Temperature Coefficient for Cast and Sintered AlNiCo | ||
|---|---|---|
| Temperature Range (°C) | Induction Br (α) (%)/°C | Intrinsic Coercivity Hci (β) (%)/°C |
| 20°C to 150°C | -0.02 to -0.03 | -0.02 to -0.03 |
| α = Δ Br / Δ T × 100 (Br @ 20°C) [ΔT = 20°C – 150°C] β = Δ Hci / Δ T × 100 (Hci @ 20°C) [ΔT = 20°C – 150°C] | ||
Physical Properties
| AlNiCo Magnets – Physical Properties | |||
|---|---|---|---|
| Property | Units | Value Sintered AlNiCo | Value Cast AlNiCo |
| Vickers Hardness | Hv | 440 | 440-620 |
| Density | g/cm³ | 6.8 – 7.0 | 6.9 – 7.3 |
| Curie Temp TC | °C | 810 – 860 | 740 – 860 |
| Curie Temp TF | °F | 1,490 – 1,580 | 1,364 – 1,580 |
| Specific Resistance | μΩ·Cm | 50-70 | 45 – 75 |
| Bending Strength | kN/mm² | 0.35 – 0.76 | 0.05 – 0.31 |
| Tensile Strength | kN/mm² | 0.35-0.45 | 0.02 – 0.15 |
| Thermal Expansion | °C-1 | +11.0 to +12.4 ×10-6 | +11.0 to +13.0 ×10-6 |
| The listed values are approximate and should be used as a reference. Any magnetic or physical characteristics should be substantiated before selecting a magnet material. Please engage a Ningbo Empire engineer before selecting a design path. | |||
Cast and sintered routes remain separate. Temperature limits require an adequate length-to-diameter ratio and a suitable magnetic circuit. Grouped headers, nominal/minimum distinctions and all original design notes are retained.
Engineering Guide
Permanent Magnet Material & Temperature Selection
Evaluate AlNiCo temperature stability together with coercivity, circuit geometry and demagnetization risk.
Compare magnet materialsFrequently Asked Questions
Why does AlNiCo have such good temperature stability?
AlNiCo's magnetic mechanism — shape anisotropy of elongated FeCo particles in a NiAl matrix — is inherently temperature-insensitive. Its Curie temperature of 850°C is 3× that of NdFeB (310°C), so normal operating temperatures barely affect the magnetic structure.
Why is AlNiCo's coercivity so low?
The same physics that gives temperature stability gives low resistance to demagnetization. AlNiCo magnets must be magnetically 'long' (high L/D ratio) so they operate at a favorable point on their demag curve. Short or disc-shaped AlNiCo magnets will partially demagnetize themselves.
Is AlNiCo still worth using in modern applications?
Absolutely — when temperature stability is critical. Electric meters, aerospace sensors, radar systems, and scientific instruments still rely on AlNiCo because AlNiCo offers low reversible temperature drift for selected instrument and sensor designs.. It also handles 450°C+, far beyond NdFeB or SmCo.
Can I get AlNiCo in custom shapes?
Yes — cast AlNiCo pours into nearly any geometry: horseshoes, E-cores, rings with poles, complex 3D shapes. This eliminates assembly operations that rare-earth magnets require. Send your drawing for a quote.
Available Geometries
AlNiCo is available cast (complex shapes) or sintered (small precision parts):
- ✓Cast bars, rods & U-shapes — classic instrument geometries
- ✓Pot magnets & assemblies — concentrated flux holding structures
- ✓Complex castings — horseshoes, custom flux paths to your drawing
- ✓Sintered small parts — ±0.05 mm precision for miniatures
- ✓Bonded AlNiCo — machinable composite on request
Machining & Dimensional Tolerances
Cast AlNiCo is near-net-shape; grinding only on functional faces:
| Process | Typical Tolerance | Notes |
|---|---|---|
| As-cast | ±0.3–0.5 mm | Most economical |
| Ground | ±0.05 mm | Pole faces and mounting faces |
| Sintered | ±0.05 mm | Precision small parts |
| Machinability | Note | Cast AlNiCo is hard — machining by grinding only |
Test & Quality Documentation
What ships with your parts — scoped per project during quotation.
Magnetic Properties
Certificate of Analysis with measured Br / Hcb / Hcj / (BH)max against the specified grade of your AlNiCo parts, from our demagnetization-curve test equipment.
Dimensional Inspection
Dimensional reports by gauge or CMM as agreed in the inspection plan; critical dimensions identified together during DFM review.
Compliance & Project Docs
RoHS / REACH declarations on request, and FAI / PPAP documentation per project requirements.
Process reference images are separated from the product gallery. They illustrate equipment and handling topics; they do not establish ownership of a facility, a customer delivery, or project-specific inspection results.
Factory Tour
Inside AlNiCo Magnets Manufacturing
Cast and sintered AlNiCo require controlled alloy melting, heat treatment, finish machining and material verification before protective packing.
4 process viewsProduct-specific manufacturing
1 inspection viewRelevant quality equipment
1 packing viewProduct-appropriate protection
End-to-end process visibilityManufacturing · inspection · packing documented in one focused route
Manufacturing processInspection & testingPacking & dispatch
Hot AlNiCo Casting
Glowing alloy castings leave the furnace before shakeout and controlled cooling.
Powder-Metallurgy Hot Pressing
Vacuum hot-press equipment supports sintered routes and special geometries.
Controlled Heat Treatment Line
Programmed thermal treatment stabilizes alloy structure and magnetic response.
Post-Treatment Material Check
Hardness and surface condition are checked after heat treatment and finishing.
Manufacturing, inspection and packing photographs for this product family.Equipment route varies by material and geometryRemote video inspection available before shipment
Have a Drawing or Specification?
Send it to our team for engineering review and quotation — grade recommendation included.