1. Body Wash

Probable causes:

- Drilling under extremely abrasive conditions

- Overwhelming flushing volume

Suggested actions:

- Reduce flushing volume

- Slow drill rotation to create larger cuttings for more effective flushing

- Use drilling foam to assist in the removal of rock cuttings

- Regularly clean the drill holes

2. Skirt Wring Off

Probable causes:

- Misalignment due to hole deviation

- Improper feed pressure

- Steel fatigue

- Worn, broken, or mismatched threads

- Excessive rotational forces from operating with dull carbides

Suggested actions:

- Lower percussion and feed during the initial drilling (collaring)

- Use alignment tools and improve drilling practices for a straighter hole; Use bits with a drop center face design and/or a retract body

- Regularly sharpen dull carbides

- Avoid striking the external bit body

- Reduce the power of impacts

3. Split Skirt

Probable causes:

- Misalignment from hole deviation

-  Loose thread joints during drilling

- Drilling with excessively worn threads

Suggested actions:

- Use alignment tools and improve drilling practices for a straighter hole

- Use bits with a drop center face or retract body

- Change worn out components of the drill string

- Ensure thread joints are securely tightened before percussion

4. Steel Crack on Bit Face

Probable causes:

- Excessive feed force

- Use dull carbides for drilling

- Manufacturing error, inferior button hole-drilling precision

Suggested actions:

- Adjust feed force to match rock conditions

- Regularly sharpen dull carbides

- Return bit for detailed analysis

5. Carbides Pop-Out

Probable causes:

- Insufficient feed pressure

- Incorrect size match between button and button hole

- Excessive grinding of the bit body

- Drilling in very soft or extremely abrasive conditions

- Free hammering

Suggested actions:

- Increase feed pressure

- Adhere to correct carbide sharpening process to prevent excessive bit body grinding. Replace worn out bits.

- Commence full percussion only when the bit is in complete contact with rock

6. Snake Skin or Micro-Cracks in Carbide

Probable causes:

- Drilling in non-abrasive rock such as limestone, leading to micro-fractures in the carbide, and it looks like snake skin.

- Incorrect intervals of carbide grinding

- The rock leaves a shiny surface on the buttons and a fatigue in the surface of the cemented carbide, leading to button failure

Suggested actions:

- Shorten grinding intervals when drilling in non-abrasive

rock

- Sharpen carbides upon dullness or the appearance of micro-cracks, appropriating proper procedures

- Regular inspection of carbides

- Use a softer carbide grade

7. Carbide Chipped & Carbide Cracked

Probable causes:

- Overdrilling of the bit

- Drilling in non-abrasive rock causes a shiny surface on the buttons

- Improper grinding intervals

- Too hard carbide grade for the rock condition

- Button not making contact with virgin material on impact

Suggested actions:

- Reduce intervals between grinds. Regrind when wear flats reach a maximum of 1/3 of the button diameter

- Regularly inspect and grind bits to eliminate surface micro-cracks on the carbides

- Select an appropriate hardness of the carbide for drilling application

- Do not initiate percussion until the bit is in full contact with the rock

8. Carbides Crashed Down to Level of Bit Body & Carbides Crashed Inside the Bit Body

Probable causes:

- Overdrilling in non-abrasive rock such as limestone, leading to micro-fractures in the carbide, and it looks like snake skin.

- Excessive carbide protrusion due to poor grinding practices

- Incorrect grinding intervals

- Unsuitable carbide grade

Suggested actions:

- Shorten the intervals for grinding when drilling in non-abrasive rock

- Regularly inspect and grind the bits although the buttons may not appear worn, just polished, to lessen micro-cracks on the carbide surface

- Use wet grinding to avoid snake skin fatigue

- Choose suitable grade of carbide