Deep Hole Drilling for Long Tubes: Straightness at Extreme Depths
Some of the most demanding deep hole drilling jobs involve drilling a small-diameter hole through several meters of steel with near-perfect straightness. The classic application is gun barrel drilling — the process that gun drilling is named after. Defense applications remain the most stringent driver of long tube drilling standards today, from rifle barrels to artillery components and missile guidance housings. The challenge is straightness. A 5mm hole through 2 meters of steel at a 100:1 L/D ratio needs to be straight to within a few hundredths of a millimeter per meter. If the hole drifts, the wall thickness changes, and the part is scrap. For defense-grade components, the stakes are even higher because barrel straightness directly affects projectile accuracy. ...