1. Break across the Chuck Ring Bearing Surface

Probable causes:

- Worn out bit chuck rings

- Insufficient lubrication

- Worn out guide bushing

Suggested actions:

- Check the status of the bit, retaining rings, and guide bushing prior to drilling

- Ensure using appropriate and adequate hammer oil

- Replace aged components of the hammer with new ones

2. Break across the Splines

Probable causes:

- In relation to DTH hammer diameter, the diameter of bit head is too big

- Too much torque

- Worn out driver sub

Suggested actions:

- Modify drill settings for oversized drill bits

- Utilize a larger DTH hammer suitable for the bit size

- Adjust torque according to the rock conditions

- Replace worn out hammer components with new parts

3. Piston Striking Face Breakage

Probable causes:

- Worn out guide bushing

- Worn out piston, bit retaining ring, or driver sub

Suggested actions:

- Check the status of the piston, bit retaining rings, driver sub and

guide bushing prior to drilling

-Replace worn out hammer components with new parts

4. Shoulder damage

Probable causes:

- Incorrect feed force

Suggested actions:

- Adjust feed force to keep the carbide working against the rock; increase on softer rocks but reduce as more drill pipe is added thus naturally increasing the feed force

5. Piston striking face damage

Probable causes:

- Inadequate lubrication

- Debris trapped between the bit and piston

Suggested actions:

- Ensure using appropriate and adequate hammer oil

- Maintain tight hammer joints and cleanse the driver sub, bit retaining ring, and drive splines consistently

- Inspect hammer check valve assembly to ensure functionality

6. Broken foot valve

Probable causes:

- Worn out piston, drive splines, or driver sub

- Misalignment

- Lack of lubrication

Suggested actions:

- Check the status of the piston, bit, and driver sub prior to drilling

- Replace worn out hammer components with new parts

- Employ alignment tools and drill practices for straighter boreholes; opt for bits with a concave face design

- Use suitable and sufficient hammer oil