| 摘要 |
PURPOSE: A manufacturing method of a drill and a print wiring board is provided to appropriately discharge cut chips through a cut chip discharging groove of the drill, so load is not applied to the drill. CONSTITUTION: A drill(10) comprises a blade unit(40), a cutting edge(30), a cut chip discharging groove(20), and a shank unit(12). The cutting edge is formed in the front end of the blade unit. The cut chip discharging groove is formed in outer periphery of the blade unit. Predetermined torsion angle of the cut chip discharging groove is 42~ 53° and surface roughness(Ra) is 0.01~0.11 micron meters.
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