Rectangular 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.

Rectangular SmCo (samarium cobalt) magnets are the most critical component in internal permanent magnet (IPM) 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 rectangular 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 rectangular profile, Vanguard can provide sample shipment within 10–15 days and mass-production support for rotor assembly or bare-magnet supply.

Quick View

Rectangular SmCo Magnet Selection Snapshot

SmCo5 / Sm2Co17

Available Grade Families

SmCo 1:5 and 2:17 grades support compact motors, sensors, aerospace systems and harsh-duty assemblies.

250-350 °C

High Temperature Stability

Stable magnetic output under thermal cycling, vibration and corrosive working environments.

Block Fit

Geometry Control

Length, width, thickness, chamfer, slot fit and magnetization direction 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

Thermal cycles

Sensors

Signal stability

IPM Motors

Slot fit

Industrial Systems

Corrosion

Medical Devices

Reliability

1Drawing ReviewLength, width, thickness, tolerance

2Grade MatchBr, Hcj, thermal stability

3Machining PlanGrinding, chamfer, surface finish

4MagnetizationThickness, length, width direction

5InspectionFlux, size, polarity, appearance

Industries Served

Key Applications

Aerospace & Aviation

Aerospace systems demand materials that perform in extreme temperatures (-200°C to +350°C), vacuum, and high vibration.SmCo’s low temperature coefficient of remanence ensures consistent magnetic performance across thermal cycles. The rectangular form factor supports modular, lightweight design — critical for weight-sensitive aerospace equipment. It is also non-corrosive and does not require protective coatings, reducing system complexity and failure risks.

Sensors & Position Detection Systems

Rectangular SmCo magnets generate a stable, uniform magnetic field that allows accurate detection by Hall or magnetoresistive sensors. Unlike irregular shapes, rectangular blocks ensure repeatable flux density and consistent signal output. They maintain magnetic stability under vibration, high temperature, and corrosive conditions, making them ideal for long-term precision sensing in automotive, industrial, and aerospace systems where signal drift cannot be tolerated.

Industrial Motors

Rectangular Samarium–Cobalt (SmCo) magnets are widely used in high-performance industrial motors where neodymium (NdFeB) magnets cannot maintain performance due to high temperature, strong demagnetizing fields, or long-term stability requirements. Their rectangular (block) shape is ideal for rotor lamination slots, precise assembly, and uniform magnetic flux distribution.

Medical Equipment

SmCo is biologically inert and stable during autoclaving (high-temperature sterilization).
Rectangular blocks are used in small, precise medical devices where consistent magnetic force and thermal resistance are required. Unlike NdFeB, SmCo does not require surface coatings that could contaminate medical environments.

Military & Defense

Employed in IPM 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

SmCo magnets (especially Sm₂Co₁₇ grades) operate reliably at 250–350°C, and some grades up to 500°C without significant demagnetization — a range where neodymium magnets degrade rapidly.The rectangular shape fits precisely into rotor slots, providing consistent magnetic flux across the air gap, improving torque stability, reducing cogging, and maintaining high power density in extreme thermal environments. Their high coercivity resists demagnetization from reverse magnetic fields in high-load motor operation.

Magnetic Performance

Grade & Magnetic Properties

Standard grades for rectangular SmCo magnets. All values at 20 °C. Values are typical; exact grade selection is confirmed per application temperature, magnetic circuit, 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 rectangular SmCo Magnets: While rectangular 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

Rectangular magnets are defined by length (L), width (W), and thickness (T). Standard tolerance is ± 0.05 mm on all dimensions; tight-tolerance ± 0.03 mm is available on request. Chamfering, radius edges, slots, holes, and matched-set grinding can be supplied for precision assembly.

Dimension	Minimum	Maximum	Standard Tol.
Length (L)	1 mm	200 mm	± 0.05 mm
Width (W)	1 mm	200 mm	± 0.05 mm
Thickness (T)	0.5 mm	50 mm	± 0.05 mm

Design Support

How to Specify Rectangular SmCo Magnets

Grade Selection

SmCo5 offers excellent thermal stability and low temperature coefficient. Sm2Co17 is preferred for higher energy product, higher working temperature, and stronger resistance to demagnetization.

Motor Slot Fit

For IPM and embedded rotor designs, length, width, thickness, corner radius, chamfer, and coating thickness should be confirmed together to avoid assembly stress and air-gap variation.

Magnetization Direction

Thickness, length, width, pair-matched, and custom magnetization can be supplied. Magnetization direction should be marked clearly on drawings for stable production and inspection.

Custom Manufacturing

Available Custom Features

Geometry

Block, bar, plate, thin slice, chamfered block, radius-edge block, slot, step, hole, and precision-ground surface.

IPM motor, sensor module, coupling, holding device, high-temperature actuator.

Tolerance

Standard tolerance, tight tolerance, matched height set, batch sorting, and surface flux grouping.

Precision rotor assembly, automated bonding, sensor calibration, consistent output force.

Surface Treatment

Uncoated, passivation, NiCuNi, epoxy, parylene, or application-specific coating after evaluation.

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

Production Control

Manufacturing & Quality Assurance

Rectangular SmCo magnets are produced through alloy preparation, powder milling, magnetic-field pressing, vacuum sintering, aging heat treatment, slicing or EDM, surface grinding, optional coating, magnetization, and final inspection. The process is designed to keep magnetic performance stable while maintaining tight mechanical dimensions.

Magnetic Inspection

Br, Hcb, Hcj, (BH)max, surface flux, flux direction, and batch consistency can be tested according to drawing or project specification.

Dimensional Inspection

Length, width, thickness, parallelism, perpendicularity, chamfer, radius, hole position, and coating thickness are checked before packing.

Documentation

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, length, width, thickness, tolerance, chamfer or hole requirement, grade or working temperature, magnetization direction, coating 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 temperature and required magnetic output.

Support

Frequently Asked Questions

When should I choose a rectangular SmCo magnet over a rectangular NdFeB magnet?

Choose rectangular 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 rectangular 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 rectangular 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 rectangular 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 rectangular 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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Rectangular SmCo Magnets

Description

Rectangular SmCo Magnets

Rectangular SmCo Magnet Selection Snapshot

Key Applications

Grade & Magnetic Properties

Coating & Plating Options

Dimension Capability

How to Specify Rectangular SmCo Magnets

Available Custom Features

Manufacturing & Quality Assurance

Information Needed for Fast Quotation

Frequently Asked Questions

Get in Touch with Us

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