Z-LION brand dry core drill takes only 10 seconds to drill through medium hard granite tiles of 2cm thickness. It can be used continuously. For hard granite India Red tile of 1.7mm thickness, it takes only 12 seconds to drill through. It can drill 36 holes continuously each time.
Max 7700 RPM for diameter of 32mm and 35mm. Max 6000RPM for diameter of 40mm and 45mm. Note: for continuous dry coring operation, it is better to have water colling after drilling 3 holes to avoid over heating.