1/2 inch 190.5 mm Tricone Bit

IADC

Rok Formation

WOB (KN/mm)

RPM(r/min)

417/427/437

Low compressive strength, high drill-ability and extremely soft formation, like shale, clay, sandstone, conglomerate etc

0.35~0.90

140~70

447

Low compressive strength, high drill-ability and soft formation, like shale, clay, sandstone, soft limestone, salt rock, plaster

etc.

0.37~1.00

140~60

517

Low compressive strength, high drill-ability and soft formation, like shale, clay, sandstone, soft limestone, salt rock, etc

0.37~1.00

120~50

527

Soft formation with low compressive, like Low compressive strength, high drill-ability and soft formation, like shale, clay,

sandstone, soft limestone, salt rock, anhydrite etc.

0.35~0.90

120~50

537/547

Low compressive strength, medium hard formation with hard abrasive interlayer, like Hard shale, anhydrite, soft limestone,

sandstone, dolomite with mezzanine, etc.

0.50~1.05

110~40

617/627

High compressive strength, medium hard and thick hard interlayer, like hard shale, limestone, sandstone, dolomite, etc.

0.50~1.05

80~40

637/737

High compressive strength, medium hard and high abrasive formation, like limestone, dolomite, sandstone, chert, etc.

0.70~1.20

70~40