Top Hammer Button Bit: How It Works, Uses & Maintenance

Proper top hammer bit maintenance can significantly reduce drilling costs and extend bit life.

1.Daily/After Each Use Cleaning and Inspection

Clean thoroughly after every shift or drilling operation: Remove rock dust, cuttings, debris, and mud from the bit face, buttons, flushing holes, and threads using compressed air, water, or a wire brush. Blocked flushing holes reduce cooling and cuttings removal, leading to overheating and faster wear.

Inspect visually:

• Check carbide buttons for flattening, rounding, chipping, cracking, or mushrooming.
• Look at the bit body (face and gauge) for cracks, wear, or steel wash (erosion around buttons).
• Examine threads for damage, galling, pitting, or seizing — apply anti-seize lubricant on threads before re-use or storage.
• Measure button protrusion/height if possible (many manufacturers provide wear limits).
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Signs it’s time to regrind (don’t wait until severely worn):

• Buttons are flat or mushroomed (reduced penetration rate).
• Increased vibration or “chatter.”
• Slower ROP (rate of penetration).
• More dust or smaller cuttings (re-drilling same material).
• Steel face starting to contact rock bottom.
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2.Regular Regrinding (Sharpening) — The Most Important Maintenance

Regrinding restores the original button profile (spherical, ballistic, etc.), restores sharp edges, and can extend bit life 3–10 times compared to non-ground bits.

When to grind: Typically after 200–600 meters drilled (depends on rock abrasiveness — softer rock allows longer intervals; very abrasive rock needs frequent grinding). Some modern bits (e.g., Sandvik Autobit) extend the first interval significantly.

How it’s done:

• Use diamond grinding cups/wheels on handheld pneumatic grinders (e.g., Sandvik, Epiroc, or CME models) or semi-automatic stationary grinders for high-volume shops.
• Grind each button to match the original shape and protrusion — follow manufacturer guidelines for angle and depth.
• Cool with water during grinding to avoid overheating the carbide.
• After grinding, clean and inspect again.

Frequency example (from real operations): First regrind after ~400 m, second after another 200–300 m.

• Proper regrinding prevents button chipping (most common failure mode when over-drilled).

3.Proper Operation to Reduce Wear

• Match bit design (button shape, face contour, thread type) to rock conditions.
• Optimize drilling parameters: Correct feed pressure, rotation speed (usually 50–150 rpm), impact energy, and flushing volume/pressure — too much or too little causes excessive wear.
• Avoid free hammering (impacting without rock contact) — it can cause button loss or cracking.
• Use good flushing (air or water) to clear cuttings quickly.

4.Storage and Handling

• Store in a dry, clean place to prevent rust or corrosion.
• Avoid dropping or banging the bit.
• Apply thread lubricant before connecting to rods.
• Rotate bits in inventory to use oldest first.

Good maintenance ensures your top hammer button bits deliver consistent performance throughout their service life.