Premium NdFeB Ring for High-Performing Loudspeakers

Surface	Coating	Thickness μm	Color	SST Hours	PCT Hours
Nickel	Ni	10～20	Bright Silver	>24～72	>24～72
Nickel	Ni+Cu+Ni	10～20	Bright Silver	>24～72	>24～72
Black Nickel	Ni+Cu+Ni	10～20	Bright Black	>48～96	>48
Cr3+Zinc	Zn C-Zn	5～8	Brighe Blue Shining Color	>16～48 >36～72	---
Sn	Ni+Cu+Ni+Sn	10～25	Silver	>36～72	>48
Au	Ni+Cu+Ni+Au	10～15	Gold	>12	>48
Ag	Ni+Cu+Ni+Ag	10～ 15	Silver	>12	>48
Epoxy	Epoxy	10～20	Black/Grey	>48	---
	Ni+Cu+Epoxy	15～30		>72～108	---
	Zn+Epoxy	15～25		>72～108	---
Passivation	---	1～3	Dark Grey	Temporary Protection	---
Phosphate	---	1～3	Dark Grey	Temporary Protection)	---

Item	Parameters	Reference Value	Unit
Auxiliary Magnetic Properties	Reversible Temperature Coefficient Of Br	-0.08--0.12	%/℃
	Reversible Temperature Coefficient Of Hcj	-0.42～-0.70	%/℃
	Specific Heat	0.502	KJ·(Kg ·℃)-1
	Curie Temperature	310~380	℃
Mechanical Physical Properties	Density	7.5~7.80	g/cm³
	Vickers Hardness	650	Hv
	Electrical Resistance	1.4x10-6	μQ ·m
	Compressive Strength	1050	MPa
	Tensile Strength	80	Mpa
	Bending Strength	290	Mpa
	Thermal Conductivity	6～8.95	W/m ·K
	Young's Modulus	160	GPa
	Thermal Expansion(C⊥)	-1.5	10-6/℃-1
	Thermal Expansion(CII)	6.5	10-6/℃-1

Application: NdFeB ring are widely used in hollow cup motor, vacuum cleaner motor, hair dryer motor, loudspeaker and other fields. In motor applications,it has very high requirement on magnet geometric dimension and magnet property, the minimum tolerance can be within 0-0.03mm.In loudspeaker application, the magnet are normally with Zn coating, delivery under un-magnetized condition, magnet grade like N, M and H series grade, normally loudspeaker magnet don't need higher grade.Another application is for cosmetic market,we are providing millions pieces ring magnet to our clients all over the world, the magnets are used for packaging box,axial magnetized or multipole axial magnetized like 2 or 4 poles, and not only for pure magnet, we are also avaialbe for some magnet assembly. Products customized: Our ring magnet can be customized from 3mm-200mm outer diameter, 1mm-150mm inner diameter, thickness from 1mm-70mm.It also need coating most of the time, like NiCuNi, Zn, Epoxy and so on...