What happens when the drill bit starts balling in air rotary drilling?

• A. Increases cutting efficiency
• B. Causes the bit to spin faster
• C. Reduces cutting efficiency and slows drilling
• D. Improves sample quality

Answer: (C)

Balling happens when cuttings stick to the bit and to each other, forming a sticky ball that wraps around the bit instead of being carried away by the airstream. This ball covers the cutting surfaces and blocks the airflow needed to lift chips to the surface. With the bit obstructed and removal hindered, cutting efficiency drops and more energy is wasted fighting the ball, so penetration slows. It doesn’t make drilling faster, and it doesn’t improve sample quality—often it can even complicate sampling or require cleaning and pullbacks.