Abstract
We developed a new visualization method that enables to observe the chip ejection process continuously in dry drilling. The work piece material is inserted to the clear tube then the drill removes only the workpiece as a chip. This process was observed by a high-speed camera from the outside of the clear tube. The diameter of the workpiece and the inner diameter of the clear tube is almost same size and the drill diameter is smaller than them 0.1mm. Comparing three kinds of drills that have different helix angles 15, 30, 40 degrees, it was observed that the chip ejection speed using 40 degrees helix drill is the fastest in these drills even though the ejection route along the flute is the longest. To confirm the effect of the roughness of the inner surface of the hole to the chip ejection process, conventional dry drilling of aluminum alloy was also carried on. It was found that the segmented chip is formed if high helix angle drill is used but the chip jam doesn't occurred until the hole depth reaches to three times of drill diameter. As a result, a high helix angle drill is suitable for the dry drilling of aluminum alloy.
