IADC code | Applicable Formation | Main characteristics of the bit | Recommended parameters |
| Cutting structure | Normal WOB kN/mm (bit dia.) | Rotary speed (rpm) |
| 117 | Very soft with low compressive strength and high drillability, such as soft shale , clay and salt bed,etc | Hardfaced gage and all tooth surfaces, the gage fitted with compacts for enhanced gage protection , and a row of trimmers is added between gage row and heel row | 0.30~0.9. | 300~80 |
127 /137 | Soft with low compressive strength and high drillability, such as sale ,clay,salt bed and soft limestone,etc | Hardfaced gage and all tooth surfaces, the gage fitted with compacts for enhanced gage protection ,and a row of trimmers is added between gage row and heel row | 0.30~0.9. | 300~80 |
427 / 437 | Very soft formations with low compressive strength and high drillability,such as clay,mudstone,chalk, gypsum,salt,soft limestone, etc. | Large dia. Offset crested.scoop compacts in inner row,wedge compacts in outer row , high compact exposure, inequable spaced compacts arrangement,and a row of trimmers is added between gage row and heel row | 0.35~0.90 | 280~70 |
447 / 517 / 527 | Soft formations with low compressive strength and high drillability,such as mudstone,gypsum, salt,soft limestone, etc. | Large dia. Offset crested.scoop compacts in inner row,wedge compacts in outer row , high compact exposure, inequable spaced compacts arrangement,and a row of trimmers is added between gage row and heel row | 0.35~1.05 | 240~50 |
537 /547 | Medium soft with low compressive strength and harder abrasive stringers, such as hard shale, mudstone ,soft limestone and sandstone,etc | Large radius scoop compacts in inner row, wedge compacts in outer row, inequable spaced compacts arrangement , and a row of trimmers is added between gage row and heel row | 0.50~1.05 | 220~40 |
617 /627 /637 | Medium hard with compressive strength and thick and hard stringers , such as limestone ,hard shale,mudstone and sandstone,etc. | Conical compacts in inner row,spherical compacts in outer row,and a row of trimmers is added between gage row and heel row | 0.50~1.10 | 220~40 |
| 737 | Hard formation with high abrasiveness ,such as hard limestone, dolomite, hard sandstone and chert,etc | Large radius conical compacts in inner row , spherical compacts in outer row , and a row of trimmers is added between gage row and heel row. | 0.50~1.20 | 200~40 |
