IMPORT & EXPORT TRADING
A 6205 is one of the most ordered bearings in the world, and also one of the most frequent sources of wrong deliveries. Two purchase orders can both say "6205" and still arrive as different parts. Here is what actually has to be written down.
The base designation only fixes the dimensions
6205 means a single-row deep groove ball bearing with a 25 mm bore, 52 mm outside diameter and 15 mm width. Those three numbers are fixed by ISO 15 and are identical for every manufacturer.
Everything else — seals, clearance, cage, precision, grease — is decided by suffixes. That is where the surprises come from.
Seal and shield suffixes
- Open (no suffix) — no protection. Used in oil-bath or gearbox positions where the housing already seals.
- 2RS / 2RS1 / DDU / LLU — contact rubber seals on both sides. IP-grade dust protection, factory greased, maintenance-free. The default for conveyors, agricultural machinery, fans.
- ZZ / 2Z / 2ZR — steel shields on both sides. Lower friction, higher speed, but not water-resistant.
- 1RS / RS — sealed on one side only; the open side sits inside an oil chamber.
Clearance: C2, C0, C3, C4
Clearance is the internal gap between rolling elements and raceways. It is not a quality grade — it is a fit decision:
- C0 (CN) — normal. The safe default for normal fits, normal temperature.
- C3 — wider than normal. Needed when the bearing runs hot (electric motors, fans, pumps) because thermal expansion eats clearance, and when both rings are press-fitted.
- C4 — wider still. Heavy interference fits, high temperature differences.
- C2 — tighter than normal. Only for precision assemblies where vibration must be minimal.
Ordering C3 by default "to be safe" is a common mistake: too much clearance in a low-speed precision position causes noise and axial play.
GOST designation for Russian buyers
Russian drawings and customs documents often use the GOST 520 designation instead of ISO. For a 6205 the mapping is:
- 205 — open 6205
- 80205 — shielded (ZZ)
- 180205 — sealed (2RS)
Supplying both designations on the same invoice avoids arguments at acceptance.
The five lines that should be in every inquiry
- Designation with full suffix — e.g.
6205-2RS1 C3 - Quantity and required packing (single box / industrial pack)
- Precision class if not P0 — P6, P5, P4, P2
- Operating conditions: temperature, speed, load direction
- Destination and Incoterm
With those five lines a factory can quote in one working day, and the risk of a wrong shipment drops to almost zero.