GB/T308-2002Ball grading standards
Chrome Steel Ball standards
Unit: μm
| Grade |
Ball diameter variation
V Dwsmax
|
Spherical error
max
|
Surface roughness
Ramax
|
lot dia. Variation
VDws max
|
| G3 | 0.08 | 0.08 | 0.010 | 0.13 |
| G5 | 0.13 | 0.13 | 0.014 | 0.25 |
| G10 | 0.25 | 0.25 | 0.020 | 0.5 |
| G16 | 0.4 | 0.4 | 0.025 | 0.8 |
| G20 | 0.5 | 0.5 | 0.032 | 1 |
| G24 | 0.6 | 0.6 | 0.040 | 1.2 |
| G28 | 0.7 | 0.7 | 0.050 | 1.4 |
| G40 | 1 | 1 | 0.060 | 2 |
| G60 | 1.5 | 1.5 | 0.080 | 3 |
| G100 | 2.5 | 2.5 | 0.100 | 5 |
| G200 | 5 | 5 | 0.150 | 10 |
Ball hardness national standards
| Ball nominal diameter Dw/mm |
Finished steel ballhardness
HRC
|
|
| Exceed | To | |
| － | 30 | 61～66 |
| 30 | 50 | 59～64 |
| 50 | － | 58～64 |
steel ballsnominaldiameterand weight
| Nominal | Diameter | Weight (1000pcs) | Nominal | Diameter | Weight (1000pcs) | Nominal | Diameter | Weight (1000pcs) |
| 0.5mm | 0.5000 | 0.0002604 | 9/32 | 7.1438 | 1.483 | 13/16 | 20.6375 | 35.75 |
| 0.6mm | 0.6000 | 0.0005085 | 7.5mm | 7.5000 | 1.7207 | 27/32 | 21.4313 | 40.05 |
| 0.7mm | 0.7000 | 0.0008788 | 5/16 | 7.9375 | 2.035 | 7/8 | 22.225 | 44.66 |
| 0.8mm | 0.8000 | 0.002083 | 8mm | 8.0000 | 2.083 | 29/32 | 23.0188 | 49.62 |
| 1mm | 1.0000 | 0.004063 | 8.5mm | 8.5000 | 2.505 | 15/16 | 23.8125 | 54.93 |
| 1.2mm | 1.2000 | 0.007030 | 11/32 | 8.7313 | 2.708 | 31/32 | 24.6063 | 60.61 |
| 1.5mm | 1.5000 | 0.01373 | 3/8 | 9.5250 | 3.516 | 25mm | 25.000 | 63.75 |
| 1/16 | 1.5875 | 0.01628 | 10mm | 10.000 | 4.068 | 1吋 | 25.400 | 66.67 |
| 2mm | 2.0000 | 0.03255 | 13/32 | 10.3188 | 4.470 | 1-1/16 | 26.9875 | 79.97 |
| 3/32 | 2.3812 | 0.05439 | 7/16 | 11.1125 | 5.583 | 1-1/8 | 28.575 | 94.92 |
| 2.5mm | 2.5000 | 0.06357 | 15/32 | 11.9063 | 6.867 | 30mm | 30.000 | 109.8 |
| 3mm | 3.0000 | 0.1098 | 1/2 | 12.7 | 8.334 | 1-3/16 | 30.1625 | 111.6 |
| 1/8 | 3.1750 | 0.1302 | 13mm | 13.000 | 8.938 | 1-1/4 | 31.75 | 130.2 |
| 3.5mm | 3.5000 | 0.1744 | 17/32 | 13.4938 | 9.996 | 1-5/16 | 33.3375 | 150.7 |
| 9/64 | 3.5719 | 0.1854 | 14mm | 14.000 | 11.16 | 1-3/8 | 34.925 | 173.3 |
| 5/32 | 3.9688 | 0.2543 | 9/16 | 14.2875 | 11.87 | 35mm | 35.000 | 174.4 |
| 4mm | 4.0000 | 0.2604 | 15mm | 15.000 | 13.73 | 1-7/16 | 36.5125 | 198.0 |
| 4.5mm | 4.5000 | 0.3707 | 19/32 | 15.0813 | 13.95 | 1-1/2 | 38.1000 | 225.0 |
| 3/16 | 4.7625 | 0.4395 | 5/8 | 15.875 | 13.95 | 1-9/16 | 39.6875 | 254.3 |
| 5mm | 5.0000 | 0.5085 | 16mm | 16.000 | 16.66 | 40mm | 40.000 | 260.4 |
| 5.5mm | 5.5000 | 0.6786 | 21/32 | 16.6688 | 18.84 | 1-5/8 | 41.275 | 286.1 |
| 7/32 | 5.5563 | 0.6979 | 11/16 | 17.4625 | 21.66 | 1-3/4 | 44.45 | 357.3 |
| 15/64 | 5.9531 | 0.8583 | 18mm | 18.000 | 23.73 | 45mm | 45.000 | 370.7 |
| 6mm | 6.0000 | 0.8788 | 23/32 | 18.2563 | 24.75 | 1-7/8 | 47.625 | 439.5 |
| 1/4 | 6.3500 | 1.042 | 3/4 | 19.0500 | 28.13 | 2吋 | 50.800 | 533.3 |
| 6.5mm | 6.5000 | 1.1201 | 25/32 | 19.8438 | 31.79 | 2-1/4 | 57.15 | 759.4 |
| 17/64 | 6.7469 | 1.249 | 20mm | 20.000 | 32.55 | 60mm | 60.000 | 878.8 |
Chrome steel ball machining accuracy in the 10G～1000G。
Production specification Φ2.5mm ～Φ60mm