Key Analysis of Failure Modes in High Air Pressure DTH Drill Bits？
In high air pressure down-the-hole (DTH) drilling operations, the drill bit is a critical and high-consumption component that directly impacts efficiency and cost. Studies show that the bit cost can exceed 20% of total project expenses — making durability and reliability essential for cost-effective drilling.
Failure of the Impact End Face
The rear end of the bit experiences repeated, high-frequency impacts from the hammer piston, leading to pitting, spalling, and local collapse — typical signs of impact fatigue damage. Key reasons include:
- High surface hardness and brittleness of the carburized layer, causing cracks;
- Low core hardness (below 35HRC), resulting in plastic deformation;
- Continuous crack growth leading to progressive spalling and concavity.
Spline Failure
The spline connects the bit with the hammer and bears both rotational torque and impact load. Common issues arise from:
- Insufficient spline hardness;
- Sharp transition radii at spline roots, creating stress concentration;
- Tight or uneven fit between splines.
Cutting Edge and Button Failure
Common failure modes of the bit crown include edge chipping, button loss, and brittle fracture. Cracks usually initiate along the carbide insert holes due to excessive brittleness and interference-fit stress.
At XLG Drill Tools, we enhance bit performance by optimizing heat treatment, improving spline geometry, and refining carbide insertion technology — achieving longer lifespan, higher reliability, and reduced downtime.
Interested in upgrading your DTH drilling performance? Let’s discuss how XLG can help you drill smarter and last longer.
