Abstract
The breakage resistance of ultra-small-diameter cutting tools must be improved to extend tool life because such tools can be easily broken during machining. One method to improve breakage resistance is to optimize tool shape. However, there have been few reports of such studies for ultra-small-diameter tools. Therefore, we attempted to extend the tool life of ultra-small-diameter gun barrel drills by optimizing the shapes of their cutting parts. Tool life was examined using cemented carbide drills 15μm in diameter fabricated by electrical discharge machining. The results indicated that the tool life could be extended by changing the cutting part cross-section from a semicircle to a quadrant when the semicircular cross-section part was short. Reducing the wedge angle to less than 90°also extended the tool life.
