NDS Drilling Supply

SOFT FORMATION TRICONE BIT
The 111 IADC rock bit is designed for rapid penetration in formations having a low compressive strength and high drillability, such as clays, shale, red beds, salt, soft sandstone and soft limestone. The long, widely spaced teeth are interfitted in such a manner so as to provide a twisting-tearing action that is so essential in the soft unconsolidated formations. Lighter drilling weights and faster rotary speeds are usually employed with these efficient bits.

MEDIUM FORMATION TRICONE BIT
The 211 IADC rock bit is designed to drill formations having compressive strength of a magnitude somewhat greater than that noted in the 111 rock bit. Formations classified as medium hard to hard non-abrasive are the best suited for the 211, such as formations are hard shale, dolomite lime, hard anhydrite, slate and hard limestone. Cutter teeth are not as widely spaced or deeply cut as in the 111 rock bit. They combine twisting-tearing action with chipping-crushing action necessary for fast cutting and longer life through the relatively harder formations. The weight used on this bit is usually greater than that used on the 111 bit. Rotary speeds are decreased as weights are increased.

HARD FORMATION TRICONE BIT
The 321 IADC rock bit is designed especially to drill in hard, semi-abrasive formations, such as hard abrasive sand, hard tough shales, conglomerated, hard lime rock and chert streaks. The closely spaced teeth give the 321 a chipping-crushing action with sufficient twisting-tearing action to effectively dislodge the cuttings from the bottom hole surface. Exceptionally sturdy sections along with maximum bearing strength are designed to withstand heavy drilling weights. Slower rotary speed and increased drilling weight is recommended.