Sintered Neodymium Iron Boron(NdFeB) magnets are made from different kinds of rare earth materials, such as Nd, Dy, Fe, Al, Nb, Ga, Mo, Co and few other metals and they are the third generation rare earth permanent magnets that is the strongest magnets in the world and they feature high remanence, high corrective force and high energy products and they are more than 10 times stronger than ferrite(ceramic) magnets. They are very brittle so it is hard to machine them and the higher grades of NdFeB magnets are always more brittle than lower grades when they are machined in the cutting, drilling, milling and even coating process. 

They are very easy to rust because they are the combination of many kinds of rare earth materials so we usually need do coating/plating on them before shipment. The ordinary coatings include Nickel(Ni-Cu-Ni), Black nickel, Zinc(Trivalent), Epoxy, Tin, Gold, Silver & Parylene etc. The ordinary grades of NdFeB magnets have N35, N38 to N52, N35M, N28M to N48M, N33H to N46H, N33SH to N44SH, N30UH to N35UH and N30EH to N35EH and their BHmax is 52MGOe that is the highest grade We can make now. Their highest working temperature is 200 °C. They almost can be any size and shape, such as block, disc, ring, segment, cylinder and any special shapes. They have wide applications such as wind generators,DC motors, air conditioners, servo motors, PM motors, linear motors, VCM, medical apparatus, electronic components, toys, hand crafts and other magnetic holding and seperating products.

Neodymium disc magnets are usually made by grinding ourter diameter of semi-finished cylinders first to get a suitable tolerance disc and then we cut the disc magnets to the suitable size and then mill the two furfaces and finally do coating/plating with Nickel(Ni-Cu=Ni), Black Nickel, Zinc(Trivalent), Epoxy, Stannum, Gold, Silver or Parylene etc tc in order to keep from rusting. The highest grades for these products are N52, N48M, N44H, N42SH, N38UH and N35EH etc and this kind of Neodymium disc magnets are usually used in loudspeakers and other electronic products and magnetic assemblies. 

                                                                 Magnetic Property of sintered NdFeB Magnets

 

No.	Grade	Br		Hcb		Hcj	(BH)max		TW* L/D=0.7
		T KGs		KA/m KOe		KA/m KOe	KJ/m3 MGOe
		Nom	Nim	Nom	Nim		Nom	Nim	°C
1	N35	1.22 12.2	1.18 11.8	907 11.4	860 10.8	≥955 ≥12	287 36	263 33	≤80
2	N38	1.26 12.6	1.22 12.2	907 11.4	860 10.8	≥955 ≥12	303 38	287 36	≤80
3	N40	1.29 12.9	1.26 12.6	907 11.4	860 10.8	≥955 ≥12	318 40	303 38	≤80
4	N42	1.33 13.3	1.29 12.9	907 11.4	860 10.8	≥955 ≥12	342 43	318 40	≤80
5	N45	1.37 13.7	1.33 13.3	907 11.4	863 10.5	≥955 ≥12	366 46	342 43	≤80
6	N48	1.41 14.1	1.37 13.7	836 10.5	716 9.0	≥836 ≥10.5	390 49	366 46	≤80
7	N50	1.45 14.5	1.41 14.1	907 10.5	860 10.8	≥836 ≥10.5	406 51	390 49	≤80
8	N35M	1.22 12.2	1.18 11.8	907 11.4	860 10.8	≥1114 ≥14	287 36	263 33	≤100
9	N38M	1.26 12.6	1.22 12.2	907 11.4	860 10.8	≥1114 ≥14	303 38	287 36	≤100
10	N40M	1.29 12.9	1.26 12.6	907 11.4	860 10.8	≥1114 ≥14	318 40	303 38	≤100
11	N42M	1.33 13.3	1.29 12.9	907 11.4	860 10.8	≥1114 ≥14	342 43	318 40	≤100
12	N45M	1.37 13.7	1.33 13.3	907 11.4	860 10.8	≥1114 ≥14	366 46	342 43	≤100
13	N48M	1.41 14.1	1.37 13.7	907 11.4	860 10.8	≥1114 ≥14	390 49	366 46	≤100
14	N33H	1.18 11.8	1.14 11.4	876 11.0	820 10.3	≥1353 ≥17	263 33	247 31	≤120
15	N35H	1.22 12.2	1.18 11.8	907 11.4	876 11.0	≥1353 ≥17	287 36	263 33	≤120
16	N38H	1.26 12.6	1.22 12.2	940 11.8	890 11.2	≥1353 ≥17	303 38	287 36	≤120
17	N40H	1.29 12.9	1.26 12.6	995 12.5	916 11.5	≥1353 ≥17	318 40	303 38	≤120
18	N42H	1.33 13.3	1.29 12.9	995 12.5	939 11.8	≥1353 ≥17	342 43	318 40	≤120
19	N44H	1.35 13.5	1.33 13.3	1035 13.0	956 12.0	≥1353 ≥17	358 45	342 43	≤120
20	N46H	1.38 13.8	1.35 13.5	1035 13.0	956 12.0	≥1353 ≥17	374 47	358 45	≤120
21	N33SH	1.18 11.8	1.14 11.4	876 11.0	820 10.3	≥1592 ≥20	263 33	247 31	≤150
22	N35SH	1.22 12.2	1.18 11.8	907 11.4	860 10.8	≥1592 ≥20	287 36	263 33	≤150
23	N38SH	1.26 12.6	1.22 12.2	907 11.4	860 10.8	≥1592 ≥20	303 38	287 36	≤150
24	N40SH	1.29 12.9	1.26 12.6	907 11.4	860 10.8	≥1592 ≥20	318 40	303 38	≤150
25	N42SH	1.33 13.3	1.29 12.9	907 11.4	860 10.8	≥1592 ≥20	342 43	318 40	≤150
26	N44SH	1.35 13.5	1.33 13.3	907 11.4	860 10.8	≥1592 ≥20	358 45	342 43	≤150
27	N30UH	1.14 11.4	1.08 10.8	844 10.6	804 10.1	≥1989 ≥25	247 31	223 28	≤180
37	N33UH	1.18 11.8	1.14 11.4	876 11.0	820 10.3	≥1989 ≥25	263 33	247 30	≤180
38	N35UH	1.22 12.2	1.18 11.8	907 11.4	860 10.8	≥1989 ≥25	287 36	263 33	≤180
39	N38UH	1.26 12.6	1.22 12.2	907 11.4	860 10.8	≥1989 ≥25	303 38	287 36	≤180
40	N30EH	1.14 11.4	1.08 10.8	844 10.6	804 10.1	≥2387 ≥30	247 31	223 28	≤200
41	N33EH	1.18 11.8	1.14 11.4	876 11.0	820 10.3	≥2388 ≥30	263 33	247 31	≤200
42	N35EH	1.22 12.2	1.18 11.8	907 11.4	836 10.5	≥2388 ≥30	287 36	263 33	≤200