General description The IRWIN® HSS TCT Tip Drill Bit is designed for precision drilling in various hard materials, including hardened steel, cast iron, bronze alloys, and manganese alloyed steel. Its Tungsten Carbide Tipped (TCT) design ensures durability and efficiency during use. Technical specifications Diameter: 9.0mm Total length: 125mm Working Length: 81mm Material: Chrome Vanadium Steel, hardened to 56 Rockwell C Carbide Tip hardness: up to 50 Rockwell C Usage When using the TCT twist drill bits, it is essential to apply a coolant to enhance performance and prolong the drill bit's lifespan. Irwin recommends using a 3-6% emulsion as a coolant.