| 摘要 |
A drill can achieve extended tool life while ensuring high machining efficiency. A flute length of the drill is set to be within a range of 6D or more and 10D or less relative to an outer diameter D of the cutting edge. At least the cutting edge has its surface coated with a hard compound and the film thickness dimension of the hard compound is set to 1.0 mum or less, and the number of cutting edges is set to two. As a result, chip dischargeability and rigidity of the drill can be synergistically improved. Therefore, the life of the drill can be synergistically improved. |
