A 6205 bearing is a single-row deep groove ball bearing with a 25 mm bore, a 52 mm outside diameter and a 15 mm width. The number tells you the type and size, and any letters after it add seals, clearance or precision.
Reading the number correctly lets you specify a bearing in a few characters. The full order code can still go wrong if the suffix is missing.
How do you decode 6205?
Read it in parts. The first digit, 6, is the bearing type: a deep groove ball bearing. The next digit, 2, is the dimension series, which sets the outside diameter and width for a given bore. The last two digits, 05, are the bore code.
For bores of 20 mm and above, multiply the last two digits by five. So 05 gives 25 mm. A few small sizes use special codes, so check a table for bores below 20 mm. The standard metric sizes are set by ISO 15, which is why a 6205 from one maker fits the housing for a 6205 from another.
What do the suffixes mean?
Suffixes vary a little between makers, so ask for the maker's key. These are the common ones:
- 2RS or 2RS1 means rubber contact seals on both sides, and ZZ means metal shields on both sides.
- C3 means radial internal clearance larger than normal, often used where shaft heat or press fits reduce clearance.
- P6 or P5 indicates a tighter tolerance class than normal.
- A lubricant code may follow, such as a grease type for a high temperature or low noise.
What should a specification include?
Write the full designation, for example 6205-2RS C3, plus the following: tolerance class, cage material, grease type, packing and the standard the bearing must meet. Tolerance classes are defined in ISO 492. Our guide to bearing standards and tolerance classes explains how they work.
Add the load, speed and temperature if you are unsure of the right variant. Bearing life is calculated using methods in ISO 281, but the real life depends on fit, lubrication and contamination as much as on the number.
Also name the packing. Bearings are sold in individual boxes, and the box should carry the designation, batch and maker. Anti-rust oil protects them in transit, but it must be compatible with the grease. Ask for sealed bags inside the carton to keep moisture out on a sea voyage.
How do you check you received the right bearing?
Counterfeit and mislabelled bearings are a known problem in the trade. Check the markings on the ring and the box, and measure the bore, outside diameter and width. Spin the bearing by hand and listen for roughness.
Ask for a batch inspection report and a packing list that lists the designation and quantity. For large orders, have a sample tested by a lab for hardness and dimensions. Check that the supplier is a manufacturer or an authorised source, using the test in trader or manufacturer.
See also what bearings are made in Rajkot for the local supply picture.
Next step
We shortlist bearing makers, inspect samples and supervise loading. Book a free sourcing review with your designation list and application.