Button Bit Wear Patterns and What They Mean

If you've ever pulled a button bit out of a hole and wondered why it looks the way it does, you're not alone. The wear patterns on your bit tell a story—about the rock you're drilling, the parameters you're using, and whether you're getting the most out of your tooling.

Reading those patterns is a skill. And like any skill, it pays to learn it.

When a button bit is sharp, the percussive energy transferred into the rock is at its optimum, delivering effective rock fracture and maximum penetration rate. As wear flats develop on the buttons, energy utilization drops—rock is ground rather than fractured, and energy reflects back up the drill string, increasing loads on the tooling, drifter, and rig.

The good news is that wear patterns are predictable. Each pattern points to a specific cause. Learn to recognize them, and you can adjust your drilling approach, extend bit life, and lower your cost per meter.

Why Wear Patterns Matter

Understanding wear patterns is not just about making bits last longer. It's about drilling smarter.

When you ignore wear, you pay for it. Drilling with worn bits not only slows down penetration rates but also reduces the life of drill string components, the rock drill, and the rig itself. Over-drilling is responsible for over 90% of all premature button failures. Yet eliminating over-drilling and performing proper sharpening significantly reduces those failures.

The key is knowing when to intervene—and what the wear is telling you.

The Four Most Common Wear Patterns

1. Button Flattening (Normal Wear)

What you see: The rounded carbide buttons develop flat surfaces, ranging from small polished spots to extensive flats that cover a large portion of the button diameter.

What it means: This is the expected, normal wear pattern for any button bit in service. The carbide buttons start out sharp and round, but with use, they gradually flatten. The question is not whether flattening occurs, but how extensive it becomes before you take action.

When to act: As a general guideline, refurbish buttons before wear flats reach one-third of the button diameter to maintain penetration and productivity. Some experts recommend re-sharpening when flats reach one-quarter of the major diameter. Once flats exceed one-third, penetration rate can drop by up to 5%, and if wear continues to two-thirds, the drop can reach 30% or more.

What happens if you ignore it: As flats develop, impact energy spreads across a larger surface area instead of concentrating on a small contact point. Rock is ground rather than fractured, producing smaller cuttings, and energy reflects back up the drill string. This sacrifices the life of drill string components, contributes to hole deviation, and increases operational costs.

2. Gauge Wear

What you see: The outer buttons on the bit circumference show accelerated wear compared to the face buttons. The bit diameter may appear reduced, and the gauge buttons may be rounded off.

What it means: Gauge wear occurs when drilling through hard, abrasive materials such as sandstone and quartzite, particularly when combined with excessive rotation speed. The wear tends to be greater on the bit circumference under these conditions. Most of this wear occurs on the outer periphery buttons, causing the bit to round off around its circumference.

What happens if you ignore it: When gauge buttons are worn and sharpened without addressing the bit body, the diameter across the gauge buttons becomes smaller than the diameter of the bit shoulder. This causes the bit to bind (gauge-out) in the hole. Bits that have lost gauge diameter may walk off course, resulting in hole deviation and reduced flushing efficiency.

Solution: Restore the gauge button-to-body gap to its original condition. If necessary, grind down the bit shoulder circumference to restore adequate clearance.

3. Body Wash

What you see: The steel bit body is worn away around the carbide buttons, leaving the buttons protruding more than they should. The buttons themselves may show minimal wear, but the steel surrounding them is visibly eroded.

What it means: Body wash occurs when drilling in non-abrasive materials where carbide wear is minimal, allowing extended drilling intervals. In these conditions, continuous chip removal around the bit wears away the bit body faster than the carbides. Similar wear occurs in fractured and loose formations where constant hole cleaning and re-drilling are required to keep the hole open.

What happens if you ignore it: Over-exposed buttons lack adequate support and are vulnerable to shearing off under impact. Button loss under these conditions is often sudden and catastrophic.

Solution: Schedule grinding intervals to reduce button protrusion back to the original height. Remove some bit-body steel below the gauge buttons to restore proper clearance—typically leaving about 2 mm of wear flat and maintaining a taper clearance of 0.5 mm.

4. Snake-Skin Patterns (Thermal Fatigue)

What you see: A cracked or crazed texture on the carbide button surface that resembles snake skin or alligator hide. These are microscopic thermal fatigue cracks.

What it means: Snake-skin patterns indicate that the carbide has been subjected to repeated heating and cooling cycles—thermal fatigue. This typically results from inadequate flushing, insufficient cooling, or drilling at excessive penetration rates without proper chip removal.

What happens if you ignore it: If snake-skin is not removed, the cracks will deepen and ultimately result in button fracture. What starts as surface fatigue rapidly progresses to complete button failure.

Solution: Buttons showing snake-skin patterns should be reground immediately, even if penetration rate remains acceptable. Proper flushing with adequate coolant flow prevents the thermal cycling that causes this damage.

Additional Wear Indicators to Watch

Beyond the four main patterns, several other indicators deserve attention:

Premature or rapid wear: If buttons wear down or flatten much sooner than expected, the causes often include high rock abrasiveness, inadequate flushing, or excessive feed and impact pressure.

Uneven wear across the bit face: Uneven wear patterns signal that the bit is not well-matched to the formation or that drilling parameters are off. Check rotation speed, feed pressure, and rig alignment.

Button chipping or cracking: Broken or chipped buttons typically result from impact overload, drill bounce, misalignment, or encountering unexpected voids in the rock.

Button loss (pull-out): When buttons completely detach, over-drilling is often the root cause. Industry estimates attribute over 90% of premature button failures to over-drilling.

How to Respond to What You See

The Wear Flat Rule

A simple rule of thumb works across most drilling conditions: Regrind when wear flats reach one-third of button diameter.

• Flats < 1/6 of diameter: Bit is performing well

• Flats 1/6–1/3 of diameter: Schedule regrinding soon

• Flats > 1/3 of diameter: Regrind immediately

• Flats > 2/3 of diameter: Bit is over-drilled; expect performance loss

Some manufacturers recommend regrinding when flats reach 30% of the original button height. Adopting an “early and light” regrinding policy preserves bit life and drilling efficiency.

Adjust Drilling Parameters

Once you recognize a wear pattern, adjust your approach:

• Gauge wear: Reduce rotation speed in hard, abrasive ground

• Body wash: Shorten drilling intervals or increase flushing efficiency

• Snake-skin: Increase coolant flow and ensure flushing channels are clear

• Uneven wear: Check feed pressure consistency and rig alignment

Keep a Wear Log

Maintaining a simple drilling log—noting meters drilled, rock type, penetration rate changes, and observed wear patterns—helps forecast regrinding intervals more accurately than fixed schedules. This data-driven approach pays off in longer bit life and more predictable maintenance.

The Bottom Line

Your button bit's wear pattern is a diagnostic tool. Gauge wear tells you about rotation speed. Body wash tells you about formation type. Snake-skin tells you about flushing. And button flattening tells you when to regrind.

Learn to read these patterns, and you'll know exactly when to regrind, when to adjust parameters, and when to replace. That knowledge translates directly to more meters per bit, less downtime, and lower drilling costs.

Litian's threaded button bits are engineered with premium carbide grades and optimized button geometries for specific rock conditions—whether you're drilling abrasive granite, fractured sandstone, or anything in between. Our button bit designs incorporate advanced carbide grades and heat treatment processes to deliver sustained performance in demanding hard rock environments.

Ready to get more from your button bits? Contact us to discuss your specific drilling application, or browse our threaded button bit product line to find the right tool for your ground conditions.