Drill-Breakage

The Job That Looked Simple on Paper I had a job drilling 3mm holes through 200mm of titanium 6Al-4V. The L/D ratio was about 66:1, which is well within the range of what a gun drilling machine can handle. I had drilled similar holes in steel without any trouble. The customer needed four holes in a part used for an actuator housing. The tolerance was ±0.05mm on diameter and the straightness requirement was 0.1mm over the full length. Nothing about this job looked unusual when I quoted it. ...

How to Read a Worn Gun Drill: Visual Failure Analysis from the Shop Floor Every gun drill that comes back to the regrind station tells a story. The wear pattern is the drill’s way of telling you what went wrong down in the hole — coolant pressure, chip packing, wrong feed, you name it. I have looked at thousands of pulled drills over the years, and almost every failure mode leaves a signature you can learn to read in about thirty seconds under magnification. ...