How does increasing pit density affect the overall rate of penetration?

• A. It increases the rate
• B. It decreases the rate
• C. It has no effect
• D. It causes erratic changes

Answer: (B)

A higher density of pits on the cutting interface dulls and disrupts the cutting edges, reducing cutting efficiency. Each pit acts like a small obstacle that interrupts continuous rock removal, so more energy is spent fracturing pit walls and pushing rock around pits rather than efficiently shearing it away. The result is more friction, more heat, and less effective material removal per pass, which lowers the overall rate of penetration. In short, adding more pits makes the tool work harder for less rock removed, so the penetration rate decreases.