A condition where the weight on a bit tooth has been so great that the tooth has dulled until its softer inner portion caves over the harder case area.

• A. Spalling
• B. Pitting
• C. Galling
• D. Bradding

Answer: (D)

This question is about a wear mode that occurs when a drill bit tooth is overloaded. Bradding happens when the load on a tooth is so high that the softer inner portion yields and flows, eventually caving over the harder outer case. The result is a dulling and a distorted tooth shape because the inner material has deformed over the harder shell, compromising the cutting edge.

Spalling would show up as surface flakes breaking away due to fatigue, not a soft inner core deforming over the outer case. Pitting appears as small pits from corrosion or impact wear, and galling involves adhesive wear with material transfer and sticking. None of those describe the soft-core collapse over the hard case the way bradding does.