Tungsten Carbide Core Bit The Tungsten Carbide Core Bit, also known as a T.C. Core Bit or TC Core Bit, is a cost-effective coring tool designed primarily for geotechnical soil investigation, overburden drilling, engineering exploration and core drilling in relatively soft formations. Tungsten carbide cutting elements are embedded or bonded into a tough metal crown. During rotary drilling, the carbide cutters remove the formation around the outside of the core while the hollow