TCI Tricone Bit IADC 417/427/437 for Soft Formation Drilling The TCI Tricone Bit with IADC 417/427/437 is a rotary roller cone drilling tool specifically designed for extremely soft formations with low compressive strength and high drill-ability. Typical formations include mudstone, clay, chalk, gypsum, salt rock, soft shale, soft limestone and similar soft rock strata. Featuring TCI (Tungsten Carbide Insert) cutting structures on three rotating cones, this tricone bit