1 / 5
| IADC | Roller Cone (m/h) | Formation Hardness | Rock Type | Compress Strength | |
|---|---|---|---|---|---|
| WEM | OBM | ||||
| 111/124 | 15-30 | 18-33 | Very soft | Clay, silts, sands | Less than 25mpa |
| 116/137/437 | 9-15 | 12-18 | Soft | Claystone, marl, lignite, sandstone, tuff | 25-50mpa |
| 136/137/517/527 | 4.5-9 | 6-12 | Medium soft | Claystone, marl, silts, anhydrites, tuff | 50-75mpa |
| 211/217/517/537 | 2.5-6 | 3-6 | Medium | Mudstone, limestone, sandstone (calcareous) | 75-100mpa |
| 211/236/537/617 | 1.5-2.5 | 1.5-3 | Medium hard | Limestone, anhydrites, dolomite | 100-120mpa |
| 311/347/627/637 | 1-1.5 | 1-1.5 | Hard | Shale (calcareous), sandstone (siliceous) | 100-200mpa |
| 637/737/837 | 1 | 1 | Very hard | Quartzite, Igneous rocks | More than 200mpa |