For 600 and 6900 extra small series miniature ball bearings, GB/T 276 is one of the controlling documents. The sections below describe its scope, the properties it does NOT decide and which standard does decide them, the equivalent designations, and the full size range.
GB/T 276 — Scope
GB/T 276 is the Chinese national standard for the boundary dimensions of single row deep groove ball bearings, identical in the dimensions it fixes to ISO 15 for this bearing type. A 6204 supplied to GB/T 276 mounts in the same seat as one supplied to ISO 15 or DIN 625-1.
What GB/T 276 Does Not Fix
It fixes dimensions. Load ratings follow GB/T 6391 (equivalent to ISO 281), tolerances GB/T 307.1 (ISO 492) and internal clearance GB/T 4604.1 (ISO 5753-1).
This division of labour is the thing to carry away from any bearing standard. A boundary dimension standard makes bearings interchangeable; it does not make them equivalent. Two bearings of the same designation from different makers mount in the same seat and are not required to have the same load rating, the same internal design, the same cage or the same speed limit.
Dimensions Supplied to GB/T 276
| Designation | Bore d (mm) | Outer diameter D (mm) | Width B (mm) | Chamfer r min (mm) |
|---|---|---|---|---|
| 693 | 3 | 8 | 3 | 0.15 |
| 694 | 4 | 11 | 4 | 0.15 |
| 695 | 5 | 13 | 4 | 0.2 |
| 696 | 6 | 15 | 5 | 0.2 |
| 697 | 7 | 17 | 5 | 0.3 |
| 698 | 8 | 19 | 6 | 0.3 |
| 699 | 9 | 20 | 6 | 0.3 |
| 623 | 3 | 10 | 4 | 0.15 |
| 624 | 4 | 13 | 5 | 0.2 |
| 625 | 5 | 16 | 5 | 0.3 |
| 626 | 6 | 19 | 6 | 0.3 |
| 627 | 7 | 22 | 7 | 0.3 |
| 628 | 8 | 24 | 8 | 0.3 |
| 629 | 9 | 26 | 8 | 0.3 |
| 634 | 4 | 16 | 5 | 0.3 |
| 635 | 5 | 19 | 6 | 0.3 |
| 638 | 8 | 28 | 9 | 0.3 |
National Equivalents
ISO 15 and DIN 625-1 cover the same bearings with the same dimensions.
This product is supplied against ISO 15 / DIN 625-1 / GB/T 276, which names the documents it is made to.
When to Cite GB/T 276
GB/T 276 is the Chinese national standard and is what a Chinese manufacturer works to, so citing it removes any ambiguity on an order placed in China. It restates the same dimensions as its ISO parent, so quoting both — the GB/T number and the ISO number — is the practice that survives a supply change.
