Arc SmCo Magnets

Description

Product Overview

Samarium Cobalt (SmCo) magnets are a class of high-performance rare earth permanent magnets, second only to Neodymium Iron Boron (NdFeB) magnets in magnetic strength, but distinguished by their exceptional high-temperature stability, corrosion resistance, and magnetic reliability. Developed in the 1960s, they quickly became a critical component in industries requiring robust performance under harsh conditions, filling the gap between traditional ferrite magnets and the later-developed NdFeB magnets.

Arc (tile) SmCo (samarium cobalt) magnets are the most critical component in surface permanent magnet (SPM) electric motors. Produced from sintered samarium-cobalt powder through isostatic pressing and vacuum sintering, they combine excellent high-temperature stability and strong corrosion resistance — along with high energy density among rare-earth permanent magnet materials — with tight dimensional tolerance for reliable motor assembly.

Ningbo Vanguard Technologies supplies arc magnets across the full grade family — from standard SmCo 1:5 (SmCo5) series through high-temperature SmCo 2:17 (Sm2Co17) series — enabling precise performance matching for each motor operating environment, especially high-temperature applications. All pieces undergo full magnetic testing, dimensional inspection, and salt-spray or HAST corrosion evaluation before shipment.

Whether you need a standard catalogue geometry or a fully custom arc profile, Vanguard can provide sample shipment within 10–15 days and mass-production support for rotor assembly or bare-magnet supply.

Quick View

Arc SmCo Magnet Selection Snapshot

SmCo5 / Sm2Co17

Available Grade Families

SmCo 1:5 and 2:17 grades support high-temperature motors, sensors and aerospace magnetic circuits.

250-350 °C

High Temperature Stability

Excellent thermal stability and low reversible temperature coefficient for harsh operating environments.

Arc Fit

Motor Geometry Control

Outer radius, inner radius, angle, chord length, thickness and chamfer can be customized.

10-15 Days

Prototype Sample Lead Time

Fast sampling after drawing, grade, tolerance and magnetization direction are confirmed.

Temperature Grade Guide

SmCo5

250 °C

Sm2Co17

300 °C

High Hcj

320 °C

High Temp

350 °C

Application Demand Focus

Aerospace Motors

Stability

Automotive

Heat resistance

Industrial Motors

Corrosion

Downhole Tools

Reliability

Sensors

Precision

1Drawing ReviewRadius, angle, thickness, tolerance

2Grade MatchBr, Hcj, thermal stability

3Machining PlanArc grinding, chamfer, surface finish

4MagnetizationRadial, parallel, paired polarity

5InspectionFlux, size, polarity, appearance

Industries Served

Key Applications

Aerospace & Aviation

Used in SPM motors for aircraft auxiliary systems (such as cabin ventilation, fuel pumps, and flight control actuators), where they withstand extreme temperature fluctuations and harsh environmental conditions without magnetic performance degradation.

Automotive

Applied in electric vehicle (EV) drive motors, hybrid vehicle (HV) auxiliary motors, and engine compartment motors (e.g., cooling fans, power steering motors), adapting to the high-temperature working environment of automotive engine bays.

Industrial Motors

Utilized in high-temperature industrial SPM motors, including those for chemical processing equipment, high-temperature fans, and industrial pumps, where resistance to corrosion and high temperatures ensures long service life.

Medical Equipment

Integrated into precision SPM motors for medical devices such as high-temperature sterilizable surgical instruments, diagnostic equipment, and medical pumps, leveraging their stable magnetic performance and biocompatible corrosion resistance.

Military & Defense

Employed in SPM motors for military equipment (e.g., radar systems, missile guidance components, and military vehicles), meeting the strict requirements of high reliability, high temperature resistance, and anti-corrosion in harsh combat environments.

Power Generation

Integrated into SPM motors for high-temperature power generation equipment, including solar thermal power generation systems, geothermal power units, and industrial waste heat recovery motors, adapting to the high-temperature working environment of energy conversion processes.

Magnetic Performance

Grade & Magnetic Properties

Standard grades for arc SmCo magnets. All values at 20 °C. Values are typical; exact grade selection is confirmed per application temperature, motor speed, demagnetizing field, and assembly requirements.

Material	Grade	Remanence		Coercivity		Intrinsic Coercivity		Max. Energy Product		Curie Temp.	Max. Ope. Tem.	Temp. Coeff. of Br	Temp. Coeff. of Hcj
		Br		Hcb		Hcj		(BH)max		Tc	Tw	Temp. Coeff. of Br	Temp. Coeff. of Hcj
		T	kGs	kA/m	kOe	kA/m	kOe	kJ/m³	MGOe	(°C)	(°C)	(%/°C)	(%/°C)
SmCo₅	SmCo₅-16S	0.79–0.84	7.9–8.4	620–660	7.8–8.3	≥1830	≥23.0	118–135	15–17	750	250	−0.035	−0.28
	SmCo₅-18S	0.84–0.89	8.4–8.9	660–700	8.3–8.8	≥1830	≥23.0	135–151	17–19	750	250	−0.040	−0.28
	SmCo₅-20S	0.89–0.93	8.9–9.3	684–732	8.6–9.2	≥1830	≥23.0	150–167	19–21	750	250	−0.045	−0.28
	SmCo₅-22S	0.92–0.96	9.2–9.6	710–756	8.9–9.5	≥1830	≥23.0	167–183	21–23	750	250	−0.045	−0.28
	SmCo₅-24S	0.96–1.00	9.6–10.0	740–788	9.3–9.9	≥1830	≥23.0	183–199	23–25	750	250	−0.045	−0.28
	LTC(SmCo₅-10)	0.62–0.66	6.2–6.6	485–517	6.1–6.5	≥1830	≥23.0	75–88	9.5–11.0	750	300	20–100 °C	+0.0156%/°C
												100–200 °C	+0.0087%/°C
												200–300 °C	+0.0007%/°C
Sm₂Co₁₇	Sm₂Co₁₇-24H	0.95–1.02	9.5–10.2	692–764	8.7–9.6	≥1990	≥25.0	175–191	22–24	800	350	−0.025	−0.20
	Sm₂Co₁₇-26H	1.02–1.05	10.2–10.5	740–788	9.4–10.0	≥1990	≥25.0	191–207	24–26	800	350	−0.030	−0.20
	Sm₂Co₁₇-28H	1.03–1.08	10.3–10.8	756–812	9.5–10.2	≥1990	≥25.0	207–220	26–28	800	350	−0.035	−0.20
	Sm₂Co₁₇-30H	1.08–1.10	10.8–11.0	788–835	9.9–10.5	≥1990	≥25.0	220–240	28–30	800	350	−0.035	−0.20
	Sm₂Co₁₇-32H	1.10–1.13	11.0–11.3	812–860	10.2–10.8	≥1990	≥25.0	230–255	29–32	800	350	−0.035	−0.20
	Sm₂Co₁₇-22	0.93–0.97	9.3–9.7	676–740	8.5–9.3	≥1433	≥18.0	160–183	20–23	800	300	−0.020	−0.20
	Sm₂Co₁₇-24	0.95–1.02	9.5–10.2	692–764	8.7–9.6	≥1433	≥18.0	175–191	22–24	800	300	−0.025	−0.20
	Sm₂Co₁₇-26	1.02–1.05	10.2–10.5	748–796	9.4–10.0	≥1433	≥18.0	191–207	24–26	800	300	−0.030	−0.20
	Sm₂Co₁₇-28	1.03–1.08	10.3–10.8	756–812	9.5–10.2	≥1433	≥18.0	207–220	26–28	800	300	−0.035	−0.20
	Sm₂Co₁₇-30	1.08–1.10	10.8–11.0	788–835	9.9–10.5	≥1433	≥18.0	220–240	28–30	800	300	−0.035	−0.20
	Sm₂Co₁₇-32	1.10–1.13	11.0–11.3	812–860	10.2–10.8	≥1433	≥18.0	230–255	29–32	800	300	−0.035	−0.20
	Sm₂Co₁₇-26M	1.02–1.05	10.2–10.5	676–780	8.5–9.8	955–1433	12–18	191–207	24–26	800	300	−0.035	−0.20
	Sm₂Co₁₇-28M	1.03–1.08	10.3–10.8	676–796	8.5–10.0	955–1433	12–18	207–220	26–28	800	300	−0.035	−0.20
	Sm₂Co₁₇-30M	1.08–1.10	10.8–11.0	676–835	8.5–10.5	955–1433	12–18	220–240	28–30	800	300	−0.035	−0.20
	Sm₂Co₁₇-32M	1.10–1.13	11.0–11.3	676–852	8.5–10.7	955–1433	12–18	230–255	29–32	800	300	−0.035	−0.20
	Sm₂Co₁₇-24L	0.95–1.02	9.5–10.2	541–716	6.8–9.0	636–955	8–12	175–191	22–24	800	250	−0.025	−0.20
	Sm₂Co₁₇-26L	1.02–1.05	10.2–10.5	541–748	6.8–9.4	636–955	8–12	191–207	24–26	800	250	−0.035	−0.20
	Sm₂Co₁₇-28L	1.03–1.08	10.3–10.8	541–764	6.8–9.6	636–955	8–12	207–220	26–28	800	250	−0.035	−0.20
	Sm₂Co₁₇-30L	1.08–1.15	10.8–11.5	541–796	6.8–10.0	636–955	8–12	220–240	28–30	800	250	−0.035	−0.20
	Sm₂Co₁₇-32L	1.10–1.15	11.0–11.5	541–812	6.9–10.2	636–955	8–12	230–255	29–32	800	250	−0.035	−0.20
	LTC(Sm₂Co₁₇-18)	0.85–0.90	8.5–9.0	629–708	7.9–8.9	≥1433	≥18	135–151	17–19	840	300	−0.001	−0.25
	LTC(Sm₂Co₁₇-20)	0.90–0.94	9.0–9.4	661–732	8.3–9.2	≥1433	≥18	151–167	19–21	840	300	−0.007	−0.25
	LTC(Sm₂Co₁₇-22)	0.94–0.97	9.4–9.7	685–740	8.6–9.3	≥1433	≥18	167–183	21–23	840	300	−0.010	−0.25
	LTC(Sm₂Co₁₇-24)	0.98–1.02	9.8–10.2	724–772	9.1–9.7	≥1433	≥18	183–199	23–25	840	300	−0.012	−0.25

Typical Physical Properties (All Sintered SMCO Grades)

Parameters	Unit	SmCo₅	Sm₂Co₁₇
Density / ρ	g/cm³	8.2–8.4	8.3–8.5
Vickers Hardness / HV	–	450–500	550–600
Compressive Strength	MPa	1000	800
Bending Strength / σ	MPa	150–180	130–150
Tensile Strength / σ	MPa	400	350
Electrical Resistivity / ρ	Ω·cm	(5–6) × 10⁻⁵	(8–9) × 10⁻⁵
Coefficient of Thermal Expansion / α C⊥	10⁻⁶/K	C⊥: 12	C⊥: 11
Coefficient of Thermal Expansion / α C⊥	10⁻⁶/K	C∥: 6	C∥: 8

Magnetization Orientations Available

Surface Treatment

Coating & Plating Options

Coating of Arc SmCo Magnets: While arc SmCo magnets inherently possess excellent corrosion resistance (thanks to their low iron content, unlike NdFeB magnets), optional surface coatings are recommended for specific harsh operating environments to further enhance durability and performance stability. The choice of coating is closely matched to the application scenario, ensuring compatibility with the magnet’s high-temperature resistance and dimensional precision.

Ni·Cu·Ni Triple Layer

Industry standard for clean, low-humidity environments. Bright silver finish.

Dimension Capability

Arc magnets are defined by outer radius (R), inner radius (r), arc angle (θ), and axial length (L). Standard tolerance is ± 0.05 mm on all dimensions; tight-tolerance ± 0.03 mm available on request. Skewed and twisted configurations supported for cogging-torque reduction.

Dimension	Minimum	Maximum	Standard Tol.
Outer Radius (R)	5 mm	200 mm	± 0.05 mm
Inner Radius (r)	3 mm	195 mm	± 0.05 mm
Arc Angle (θ)	15°	180°	± 0.2°
Axial Length (L)	2 mm	150 mm	± 0.05 mm
Thickness (t = R–r)	2 mm	50 mm	± 0.05 mm

Design Support

How to Specify Arc SmCo Magnets

SmCo5 or Sm2Co17

SmCo5 is suitable for stable output and excellent temperature coefficient control. Sm2Co17 is selected when higher energy product, higher working temperature, and stronger demagnetization resistance are required.

Thermal Margin

Grade selection should consider continuous working temperature, short-time peak temperature, cooling condition, and reversible flux loss. SmCo is ideal for motors exposed to heat, vacuum, oil, or aggressive atmosphere.

Magnetic Circuit

We help review pole count, air gap, magnet thickness, arc angle, magnetization direction, and rotor sleeve design so the magnet works reliably under load and high-speed operation.

Custom Manufacturing

Available Custom Features

Geometry

Arc segment, tile magnet, skewed arc, chamfered edge, stepped profile, precision-ground radius.

SPM rotor, servo motor, high-temperature pump motor, aerospace actuator.

Magnetization

Radial, parallel, thickness direction, single-pole pair, matched set magnetization.

Optimized torque output, stable air-gap flux, reduced rotor assembly variation.

Surface Finish

Uncoated, passivation, NiCuNi, epoxy, parylene, special coating on request.

High humidity, chemical exposure, bonding process, clean assembly environment.

Production Control

From Powder to Finished Arc SmCo Magnet

SmCo arc magnets are produced by alloy preparation, powder milling, magnetic-field pressing, vacuum sintering, aging heat treatment, EDM or slicing, profile grinding, optional coating, magnetization, and final inspection. Each step is controlled to balance magnetic performance, dimensional accuracy, and mechanical reliability.

Magnetic Testing

Br, Hcb, Hcj, (BH)max, surface flux, flux consistency, and demagnetization curve can be tested according to the confirmed specification.

Dimensional Control

Outer radius, inner radius, arc angle, length, thickness, chamfer, flatness, and matching set consistency are inspected before shipment.

Validation Reports

Material certificate, dimensional report, coating report, salt spray result, thermal aging data, and RoHS/REACH documents are available on request.

Fast Quotation

Information Needed for Fast Quotation

For faster engineering review, please provide drawing or 3D file, outer radius, inner radius, arc angle, axial length, tolerance, grade or working temperature, magnetization direction, surface requirement, operating environment, sample quantity, and annual volume. If the grade is not fixed, our team can recommend a SmCo5 or Sm2Co17 option based on motor temperature and required flux output.

Support

Frequently Asked Questions

When should I choose an arc SmCo magnet over an arc NdFeB magnet?

Choose arc SmCo if your application requires high-temperature operation (above 150°C, up to 550°C), superior corrosion resistance (no need for coating), or resistance to demagnetization in harsh environments (e.g., vibration, chemical exposure).

What is the minimum order quantity for custom arc magnets?

For custom geometry, samples can be arranged from as few as 50–200 pieces. Mass-production MOQ is typically 1000–10000 pieces per specification, though this is flexible depending on magnet size and grade. Contact us to discuss your project volume.

Can you supply arc magnets already assembled into a rotor?

Yes. Vanguard provides integrated rotor assembly services — including magnet bonding, balancing, and shaft press-fitting — as part of our Magnetic Systems product line. We can supply bare arc magnets or complete rotor sub-assemblies depending on your manufacturing flow.

Do you provide material certifications and test reports?

Full material certificates (chemical composition, magnetic test data, coating thickness, salt-spray results) are provided with each shipment as standard. ROHS, REACH, and conflict-mineral declarations are available on request.

What is the lead time for arc SmCo magnets?

Prototype samples: 10–15 working days. Mass-production orders: 25–35 working days depending on grade, coating, and quantity. Rush sampling may be available — please inquire.

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Arc SmCo Magnets

Description

Arc SmCo Magnets

Arc SmCo Magnet Selection Snapshot

Key Applications

Grade & Magnetic Properties

Coating & Plating Options

Dimension Capability

How to Specify Arc SmCo Magnets

Available Custom Features

From Powder to Finished Arc SmCo Magnet

Information Needed for Fast Quotation

Frequently Asked Questions

Get in Touch with Us

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