Core drill bits consist of a hollow cylindrical shaft. At the bottom of core drill bits sits a series of square notches designed to cut through concrete, cement block and brick. A core drill motor turns the drill bit and applies downward pressure on the bit as it drills through masonry. Heat generates at the bottom of core drill bits as they grind through masonry and a constant flow of coolant is required to avoid dulling the bit's cutting teeth. The type of coating located on the cutting teeth combined with the proper flow of coolant ensures the drill bit has a long life and does not crack or damage the masonry product being drilled.
Both coated and non-coated core drill bits cut through masonry products and reinforcement rods located within the masonry, but coated drill bits cut through the material at a faster rate. Diamond chips bonded to the drill bit teeth and ceramic-bonded coatings are the most common types of drill bit coatings. Both coatings work equally well, but ceramic-coated drill bits cost less than their diamond-bonded counter parts. The wear rate between both types of coated bits and non-coated bits remains standard. Extending core drill bit life requires reducing friction and controlling heat.
Every core drill has an attachment point to affix a water line from a pressurized water tank. A hand pump located on top of the water tank forces water into a coolant passage that directs water through the drill motor and into the top of the core drill bit. The water floods the inside of the drill bit and flows along the outside of the bit shaft. As the water flows through the core drill, the water tank loses pressure, and constant attention to the water flow ensures the drill bit remains core during the drilling process.
Securing a core drill during the drilling process ensures the tool does not break free and spin from the torque created by core drill bits. Even with adequate coolant, friction increases as a core drill bit cuts deeper into masonry. This causes the core drill bit to receive high amounts of torque as the bit spins. An unsecured core drill will spin under force and cause injury to the person operating the core drill. A proper pre-use inspection of the core drill mounting points and the cutting teeth of the will reduce the chances of injury during the drilling process.