Good or good tungsten cobalt steel drill bit.
Cobalt drill good impact resistance. For the machined material hardness, or vibration machining occasions.
Tungsten bit high hardness, wear resistance. Suitable for occasions with high hardness, uniform material and no vibration (such as steel and hardened steel). That's the principle.
They are tungsten cobalt drills, which are commonly used in machining. Tungsten, cobalt and titanium drills are found in hard materials with Rockwell hardness of more than HRC32.
