Steel ball testing items and quality grading (JB/CQ105-88)
| Inspection item | Premium | First grade | Qualified product | |||
| AQL | n/AC | AQL | n/AC | AQL | n/AC | |
| Surface Quality | 0.25 | 125/0 | 0.4 | 125/1 | 0.65 | 125/2 |
| Ball diameter variation /VDws | 0.25 | 125/0 | 0.4 | 125/1 | 0.65 | 125/2 |
| Spherical error /△SPH | - | 8/0 | - | 8/0 | - | 8/0 |
| Variation of batch diameter /VDwl | Check 25 steel balls, the VDsl should meet the relevant standards | |||||
| Ball gauge value /S | Check 25 steel balls, the S should meet the relevant standards | |||||
After the steel ball is quenched, the hardness, microstructure and cracks
| Item | G5 | G10 | G16 | G20 |
| Hardness | HRC62-66 | |||
| Microstructure | Level 1-3, Level 6, Level 7 | Level 1-7 | ||
| Crack | Not allowed | |||
Bearing steel ball executive standard
JBCQ87-87 rolling bearing steel ball vibration technical conditions
| Nominal diameter of steel ball | Steel ball vibration acceleration level (DB) does not exceed | ||||
| Exceed | To | Z1 | Z2 | ||
| Batch mean | Single value | Batch mean | Single value | ||
| 5.5 | 6 | 39.5 | 41.5 | 38 | 40 |
| 6 | 7 | 40 | 42 | 38.5 | 40.5 |
| 7 | 8 | 40.5 | 42.5 | 39 | 41 |
| 8 | 9 | 41 | 43 | 39.5 | 41.5 |
| 9 | 10 | 41.5 | 43.5 | 40 | 42 |
| 10 | 11 | 42 | 44 | 40.5 | 42.5 |
| 11 | 12 | 42.5 | 44.5 | 41 | 43 |
| 12 | 13 | 43 | 45 | 41.5 | 43.5 |
| 13 | 14 | 43.5 | 45.5 | 42 | 44 |
| 14 | 15 | 44 | 46 | 42.5 | 44.5 |
| 15 | 15.5 | 44.5 | 46.5 | 43 | 45 |