A drill bit used for drilling composites should operate at approximately what speed?

• A. Use a manual drill at low speed.
• B. Use any speed; speed is not important.
• C. Use an air-driven tool capable of a free speed of up to 20,000 rpm.
• D. Use a battery drill at 50,000 rpm.

Answer: (C)

Drilling composites requires keeping heat under control to avoid damaging the material, such as resin smearing, overheating, or delamination. A tool that can run at a controlled, moderate speed is essential. An air-driven, or pneumatic, drill can deliver steady speed with good control and typically operates efficiently around 20,000 rpm, which is high enough for clean cutting but low enough to minimize heat buildup in composite layups. This makes it well suited for composite work compared with high-speed electric drills, which can overheat the material, or manual methods, which are slow and hard to control for consistent hole quality.

Using a battery drill at very high speeds, like 50,000 rpm, risks excessive heat and damage to the composite. A manual drill at low speed lacks the consistent, maintainable speed and feed needed for clean, repeatable holes in composite laminates. So, the recommended approach is an air-driven tool with a free speed around 20,000 rpm.