Things Should Know About the Sample

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All of our customized neodymium magnets are made by our factory in China.

Whether you’re looking for common NdFeB magnets, or NdFeB magnets with complex irregular shapes, this is a great opportunity to take advantage of our Free Sample Offer.

Many of our current customers test our magnets before they make a purchase to evaluate for their future project and to view the quality of our magnets.

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① Send a design drawing

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Embarking on sample making

For an efficient sample production and for delivery on our initial promise , we need to certain four points related to the magnetic requirements with our customers before sample production

Shape, Dimension, Tolerance

Neodymium Magnet Material Grade

Neodymium Magnet Surface Treatment/coatings

Magnetization and Orientation

Shape, Dimension, Tolerance

As an important part of many manufacturing products, the unqualified magnet shapes, sizes and tolerances will lead to a failure assembly. So be sure to take that into consideration if exact measurements are required for your purposes.

We have the capability to manufacture and supply almost any shape and size of custom designed permanent magnet to fit your specific needs.

In general, the magnets have standard machine tolerances — +/- 0.05mm to +/- 0.1mm. The specific tolerance varies by the magnet shape and the application field.

Feasible dimensions and tolerances for Different Shapes of neodymium magnets

Shape	Deminsion Range (mm)	Platness Tolerance (mm)	Parallelism Tolerance (mm)	Perpendicularity Tolerance (mm)
Block	0.5≤L≤10	±0.03	±0.03	<0.3°
Block	10≤L≤50	±0.05	±0.05	<0.3°
Block	L>50	±0.1	±0.1	<0.3°

Shape	Deminsion Range (mm)	Platness Tolerance (mm)	Parallelism Tolerance (mm)	Roundness Tolerance (mm)
Cylinder/Disc	1≤L≤5	±0.02	±0.02	±0.02
Cylinder/Disc	5≤L≤25	±0.05	±0.03	±0.03
Cylinder/Disc	25≤D≤50	±0.05	±0.05	±0.05
Cylinder/Disc	L>50	±0.1	±0.1	±0.05

Shape	Deminsion Range (mm)	Platness Tolerance (mm)	Parallelism Tolerance (mm)	Coaxiality Tolerance (mm)
Ring	1≤L≤3	±0.02	±0.02	±0.02
Ring	3≤L≤5	±0.03	±0.02	±0.04
Ring	5≤D≤15	±0.05	±0.03	±0.05
Ring	L>15	±0.05	±0.1	±0.1

Shape	Deminsion Range (mm)	Tolerance (mm)
Arc	T≤10	±0.04
Arc	10<T≤25	±0.05
Arc	L≤10	±0.03
Arc	10< L≤25	±0.03
Arc	25< L≤63	±0.04
Arc	L>63	±0.06
Arc	W>63	±0.05
Arc	W>63	±0.06

Neodymium Magnet Material Grade

Magnets are graded by the magnetic material from which they are manufactured. Generally speaking, the higher the grade of material, the stronger the magnet. Neodymium magnets, for example, typically range in grade from N28 to N52.

1. Material Grade classification of sintered NdFeB magnets:

The first letter N before the values is short for neodymium, meaning sintered NdFeB magnets.Letters following the values indicate intrinsic coercivity and maximum operating temperatures.

N35 – N54
N35M – N54M
N35H – N52H
N30SH – N48SH
N30UH – N42UH
N28EH – N40EH
N28AH – N35AH

Practically, the higher the grade and Hcj, the stronger the neodymium magnets, and the higher the temperature of the neodymium magnet can be exposed to, whereas, the higher the cost and the manufacturing difficulties. From the point of cost-saving and efficiency, we assist in the suitable grade selection which could hit the spot detail for your products in the commercial application.

2. Sintered Magnetic Properties Chart

As a NdFeB magnet manufacturer, our engineering team devote themselves to optimize material formula and production processes, with the aim to supply cost-effective magnet solutions. The following table shows the magnet performance.

Grade	Remanence Range (Br)		Intrinsic Coercive Force Min Value (Hcj)		Coercive Force Min Value (Hcb)		Maximum Energy Max Range (BH)		Working Temp Maximum (℃)
Unit	T	kGs	kA/m	kOe	kA/m	kOe	kJ/m3	MGOe	℃
N35	1.17~1.22	11.7~12.2	955	12	868	10.9	263~287	33~36	≤80
N38	1.22~1.27	12.2~12.7	955	12	899	11.3	287~310	36~39	≤80
N40	1.25~1.30	12.5~13.0	955	12	923	11.6	302~326	38~41	≤80
N42	1.28~1.34	12.8~13.4	955	12	923	11.6	318~342	40~43	≤80
N45	1.33~1.38	13.3~13.8	955	12	876	11	342~366	43~46	≤80
N48	1.37~1.43	13.7~14.3	955	12	892	11.2	366~390	46~49	≤80
N50	1.39~1.45	13.9~14.5	876	11	836	10.5	374~406	47~51	≤80
N52	1.42~1.47	14.2~14.7	876	11	836	10.5	390~422	49~53	≤80
N35M	1.17~1.22	11.7~12.2	1114	14	868	10.9	263~287	33~36	≤100
N38M	1.22~1.27	12.2~12.7	1114	14	899	11.3	287~310	36~39	≤100
N40M	1.25~1.30	12.5~13.0	1114	14	923	11.6	302~326	38~41	≤100
N42M	1.28~1.34	12.8~13.4	1114	14	955	12	318~342	40~43	≤100
N45M	1.33~1.38	13.3~13.8	1114	14	995	12.5	342~366	43~46	≤100
N48M	1.37~1.43	13.7~14.3	1114	14	1019	12.8	358~390	46~49	≤100
N50M	1.39~1.45	13.9~14.5	1114	13	1035	13	374~406	47~51	≤100
N52M	1.42~1.47	14.2~14.7	1114	13	1050	13	390~422	49~53	≤100
N35H	1.17~1.22	11.7~12.2	1353	17	868	10.9	263~287	33~36	≤120
N38H	1.22~1.27	12.2~12.7	1353	17	899	11.3	287~310	36~39	≤120
N40H	1.25~1.30	12.5~13.0	1353	17	923	11.6	302~326	38~41	≤120
N42H	1.28~1.34	12.8~13.4	1353	17	955	12	318~342	40~43	≤120
N45H	1.33~1.38	13.3~13.8	1353	17	963	12.1	334~358	43~46	≤120
N48H	1.37~1.43	13.7~14.3	1353	16	971	12.2	342~366	45~49	≤120
N50H	1.39~1.45	13.9~14.5	1353	16	1074	13.1	374~406	47~51	≤120
N52H	1.42~1.47	14.2~14.7	1353	16	1082	13.2	390~422	49~53	≤120
N30SH	1.08~1.14	10.8~11.4	1592	20	804	10.1	223~254	28~32	≤150
N33SH	1.13~1.18	11.3~11.8	1592	20	844	10.6	247~270	31~34	≤150
N35SH	1.17~1.22	11.7~12.2	1592	20	876	11	263~287	33~36	≤150
N38SH	1.22~1.27	12.2~12.7	1592	20	907	11.4	287~310	36~39	≤150
N40SH	1.25~1.30	12.5~13.0	1592	20	939	11.8	302~326	38~41	≤150
N42SH	1.28~1.34	12.8~13.4	1592	20	971	12.2	318~342	40~43	≤150
N45SH	1.32~1.38	13.2~13.8	1592	19	995	12.3	342~366	43~46	≤150
N48SH	1.36~1.42	13.6~14.2	1512	19	995	12.5	358~390	45~49	≤150
N28UH	1.02~1.08	10.2~10.8	1990	25	764	9.6	207~231	26~29	≤180
N30UH	1.08~1.14	10.8~11.4	1990	25	812	10.2	223~254	28~32	≤180
N33UH	1.13~1.18	11.3~11.8	1990	25	852	10.7	247~270	31~34	≤180
N35UH	1.17~1.22	11.7~12.2	1990	25	860	10.8	263~287	33~36	≤180
N38UH	1.22~1.27	12.2~12.7	1990	25	876	11	287~310	36~39	≤180
N40UH	1.26~1.30	12.6~13.0	1911	24	915	11.5	302~326	38~41	≤180
N42UH	1.30~1.35	13.0~13.5	1911	24	971	12.2	310~342	39~43	≤180
N28EH	1.04~1.09	10.4~10.9	2388	30	780	9.8	207~231	26~29	≤200
N30EH	1.08~1.14	10.8~11.4	2388	30	812	10.2	223~254	28~32	≤200
N33EH	1.13~1.18	11.3~11.8	2388	30	820	10.3	247~270	31~34	≤200
N35EH	1.17~1.22	11.7~12.2	2388	30	836	10.5	263~287	33~36	≤200
N38EH	1.22~1.27	12.2~12.7	2388	30	915	11.5	279~310	35~39	≤200
N28AH	1.02~1.09	10.2~10.9	2706	34	780	9.8	199~231	25~29	≤240
N30AH	1.07~1.13	10.7~11.3	2706	34	812	10.2	215~247	27~31	≤240
N33AH	1.11~1.17	11.1~11.7	2706	34	820	10.5	239~271	30~34	≤240

Neodymium Magnet Surface Treatment

Sintered neodymium magnet are highly vulnerable to corrosion in moist environments because of their high iron content. This vulnerability is addressed in many commercial products by adding a protective coating.

1. Surface Coationg Classification

NdFeB magnets can be coated with electroplate, epoxy and other coatings that can give them excellent corrosion resistance to prevent exposure to the atmosphere.

There are a variety of coatings available finished by our own in-house plating production lines:

Nickel-Copper-Nickel (Ni-Cu-Ni)
Nickel (Ni)
Epoxy
Zinc (Zn)
Ni-Cu-Ni plus Epoxy
Gold

Generally, Ni-Cu-Ni plating is always a standard method applied to the neodymium magnets. However, the application sometimes affects the choice of surface finishes. Be sure to consult with our engineers first to make sure the coating matches the application.

2. The most common coatings and their characteristics.

Plating Type	Plating Thickness (μm)	Color	Working Temp (°C)	SST (h)	Features
Zinc plating-blue white	5--20	Blue white	≤160	≥48	Anodic coating
Zinc plating-coloring	5--20	Coloring	≤160	≥72	Anodic coating
Ni-Cu-Ni plating	10--30	Silver	≤390	≥48	High temperature resistance
Epoxy plating	15-25	Black	≤200	≥360	Insulativity and high consistency of thickness
Ni-Cu plus Epoxy plating	20-40	Black	≤200	≥720	Insulativity and Super strong salt spray resistance
Phosphating	---	---	≤250	≥0.5	Low cost

Magnetization Orientation

Magnetic orientation is one of the key factor to make high-performance of NdFeB magnets.

Under the influence of strong external magnetic field, sintered NdFeB magnet is easy to be magnetized and obtain extremely high magnetism, which will not disappear after the external magnetic field disappears. Hence, “magnetization” is a key step of sintered NdFeB permanent magnet to obtain magnetism

The direction is irreversible once it is oriented. The magnetized directions have the strongest magnetism, but the rest is very poor and weak. Hence, it should be taken into consideration bfore we start a product design or production