Which statement about cuttings best describes drilling efficiency?

• A. Larger cuttings indicate bit wear
• B. Larger cuttings indicate efficient drilling
• C. Larger, uniform cuttings indicate efficient drilling
• D. Cutting size is unrelated to efficiency

Answer: (C)

In air rotary drilling, the size and consistency of the cuttings you see at the surface reflect how effectively the bit is cutting and how well the hole is being cleaned out. When the bit is sharp and the drilling parameters are well balanced, rock breaks off in large, uniform chunks. Those large, consistent chips indicate that energy is being efficiently used to cut and remove material, and the air stream is carrying those chips away rather than turning them into fine dust.

If the cuttings are small or powdery, or vary greatly in size, it often points to less efficient drilling—typically a worn or dull bit, or inadequate weight on the bit or airflow, which grinds instead of cleanly shearing rock and hampers chip removal.