NSK

NSK Bearings

NSK is one of the world's largest manufacturers of standard deep groove ball bearings (6000/6200/6300/6800/6900 series) and has a complete DGBB program. The most distinctive aspect of its designation system is that it uses no separator and has its own letters for seals/shields: metal shield Z/ZZ, contact rubber seal DU/DDU, non-contact rubber seal V/VV, light-contact seal DW/DDW; in addition, the narrowed CM clearance for electric motors is specific to NSK.

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Code structure

There is NO SEPARATOR; seal, cage, clearance, tolerance and grease codes are written directly after the basic designation. Examples: 6205ZZC3, 6205DDUCM, 6205VVC3

Suffix	Meaning	Example
Z	Metal shield on one side	6205Z
ZZ	Metal shields on both sides – the most common NSK variant on the market	6205ZZ
ZS	Metal shield on one side; same function as Z, NSK's alternative shield retention type (found in small/miniature series)	6205ZS
ZZS	Metal shields on both sides; same function as ZZ, alternative shield retention type	6205ZZS
DU	Contact (lip) rubber seal on one side – NBR	6205DU
DDU	Contact rubber seals on both sides – equivalent to SKF 2RS1 / FAG 2RSR / NTN LLU	6205DDU
DW	Light-contact rubber seal on one side (low friction)	6205DW
DDW	Light-contact rubber seals on both sides – low friction, equivalent to SKF 2RSL	6205DDW
V	Non-contact (labyrinth) rubber seal on one side	6205V
VV	Non-contact rubber seals on both sides – low friction, equivalent to NTN LLB	6205VV
N	Snap ring (retaining ring) groove in the outer ring	6205N
NR	Snap ring groove in the outer ring + snap ring fitted	6205NR
CM	Specially narrowed radial clearance for electric motors (NSK-specific; narrowed within the CN band, in practice runs close to C3)	6205CM
CN	Normal radial clearance (usually omitted from the code)	6205CN
C2	Radial clearance smaller than normal	6205C2
C3	Radial clearance larger than normal – for hot running / interference fits	6205C3

Markings on the bearing: On open and sealed types, the marking is applied by laser to the outer ring side face; on shielded types, it is applied to the metal shield by laser or stamping. The format is a single line: "NSK" logo + full code + country, e.g. "NSK 6205ZZ JAPAN" or "NSK 6205DDU JAPAN". On rubber seals, "NSK" and the code are additionally embossed on the seal body. The country marking varies with the place of manufacture: JAPAN, ENGLAND, POLAND, GERMANY, CHINA, THAILAND, INDONESIA, INDIA, BRASIL, USA. Next to it is a small dot-matrix laser batch/date code. The lettering is a thin, even, crisp laser mark; thick, crudely etched or red "NSK" lettering is a sign of a counterfeit.