Carbide button failure is not one problem with one cause. A broken button can result from overdrilling a worn profile, loss of steel support around the insert, impact against foreign metal, abnormal side loading, or a retention problem. A missing button can also look similar to a fractured button even though the failure path is different. The fastest way to avoid repeat failures is to classify what actually happened before changing the bit, grinding interval, operating settings, or supplier.
This guide is for mines, quarries, drilling contractors, distributors, and maintenance teams using button bits in top-hammer, tapered, or DTH drilling. The failure mechanisms below are shared only where the engineering is comparable; always follow the specific bit and hammer/drifter manufacturer's limits for your system.
1. Quick Diagnosis: What Kind of Button Failure Do You Have?
| Observed condition | What it usually indicates | First action |
|---|---|---|
| Button top is chipped or shattered but part of the insert remains | Impact/fatigue damage, often aggravated by excessive wear, shock loading, or contact with foreign material | Stop drilling and compare wear across all buttons before deciding whether the bit is recoverable |
| Fine surface cracking or “snakeskin” on the carbide | Surface fatigue that can progress if the damaged layer remains in service | Reprofile only if the bit body and insert condition remain serviceable; remove cracked surface during controlled grinding |
| Entire carbide insert is missing and the pocket is visible | Button loss rather than simple tip fracture; inspect body support, pocket condition, and whether failure repeats in the same position | Remove the bit from service and document the pocket and surrounding steel |
| Buttons stand unusually proud because steel has worn away around them | Bit-body wash has reduced steel support around the inserts | Restore acceptable body/button geometry if the manufacturer's procedure permits; otherwise replace the bit |
| Several buttons fail at similar wear level across the face | Systemic wear/maintenance or operating-condition problem is more likely than one isolated defect | Review grinding interval, rock condition, flushing, feed/rotation, and batch history |
| One new button disappears early while neighboring buttons show little wear | Localized impact or possible retention/fit issue needs investigation | Preserve the failed bit, photographs, drilling data, and batch information for supplier analysis |
2. Why Carbide Buttons Fail Before the Steel Bit Body Is Worn Out
Cemented carbide is used because it combines hardness, strength, toughness, and wear resistance, but those properties are a compromise rather than an unlimited safety margin. Sandvik describes carbide grade selection as a balance of strength, hardness, toughness, and wear resistance for the application. That means a button optimized for one formation or wear mechanism is not automatically ideal for every rock condition.[1]
Button life also depends on how the carbide is supported by the bit body. Sandvik's DTH tooling emphasizes steel support around cemented-carbide buttons and flushing geometry that removes cuttings and reduces wear.[2] Once steel support is lost, the insert can be exposed to higher bending and impact stresses even if the carbide itself still looks relatively tall.
3. Cause #1: Overdrilling Worn Buttons Until They Fracture
A button bit should not be judged only by whether carbide is still present. As the original button profile wears flat, penetration falls and impact loading changes. Boart Longyear specifically warns that over-drilled top-hammer bits exhibit broken buttons and advises refurbishing before wear flats become excessive; its field guidance uses roughly one-third of the button diameter as a general trigger, subject to the bit design and operating conditions.[3]
The important purchasing and maintenance lesson is not the exact percentage alone. It is the sequence: wear flat grows → drilling efficiency deteriorates → the operator keeps drilling → impact/fatigue loading becomes less favorable → button damage becomes more likely. If several bits from different batches fail after being run to the same severe wear condition, changing suppliers will not solve the root cause.
For a dedicated regrinding workflow, see the Button Bit Regrinding Guide.
4. Cause #2: “Snakeskin” Surface Cracks and Carbide Fatigue
Fine cracking on the button surface can appear before a dramatic fracture. Boart Longyear describes a “snakeskin” condition in which small cracks develop on carbide surfaces in some ground conditions; if the cracked layer is not removed during proper grinding, fatigue damage can progress until the button fails.[3]
Do not confuse visible microcracking with a normal polished wear surface. If the same cracking pattern appears repeatedly, record the rock unit, meters drilled, button position, and grinding history. A recurring pattern across multiple bits is more diagnostic than one isolated damaged insert.
5. Cause #3: Bit-Body Wash Leaves Too Much Button Protrusion
In some formations the steel body can wear away faster than the carbide. The result is excessive button protrusion and reduced lateral support around the insert. Boart Longyear identifies this body-wash condition and recommends restoring the gauge-button-to-body relationship where the bit design and maintenance procedure allow it.[3]
This is why a button that still has plenty of carbide height can nevertheless be at risk. The question is not only “How much carbide is left?” but also “How much steel is still supporting it?”
| Inspection point | Acceptable direction | Risk signal |
|---|---|---|
| Steel around gauge buttons | Consistent support around inserts | Deeply washed body with buttons standing unusually proud |
| Face wear | Relatively even for the formation and design | Localized erosion channels around one group of buttons |
| Flushing passages | Open and consistent with original geometry | Damage or erosion that changes cuttings flow around the face |
| Gauge condition | Maintains the required hole-clearing geometry | Severe body/gauge wear that can increase side loading during rotation or retrieval |
6. Cause #4: Foreign Metal and Abnormal Impact Loading
Carbide buttons are designed to break rock, not to repeatedly strike trapped steel. Boart Longyear's percussive-tool troubleshooting material lists contact with foreign metal such as stuck drill steel, old bits, or reinforcement as a cause of shattered buttons.[4] Similar shock loading can occur when a bit is forced through an undersize section, broken ground, or a void while the drill string is heavily loaded.
If damage appears suddenly after redrilling an old hole, clearing a stuck tool, drilling through reinforced ground, or forcing rotation during retrieval, treat the event history as part of the failure diagnosis. A supplier cannot infer this from a photograph of the bit alone.
7. Cause #5: Poor Cuttings Removal Accelerates the Conditions Around Failure
Poor flushing is not a universal direct cause of a button popping out, but it can worsen the operating environment. Cuttings that are not removed efficiently are re-crushed and recirculated, increasing wear and heat around the bit face. Sandvik's DTH bit designs explicitly use optimized flushing to aid cuttings removal and reduce wear.[2]
When button failures appear together with packed cuttings, slow penetration, unusually hot tooling, heavy face erosion, or rapid gauge wear, check the complete flushing system rather than treating the button as an isolated consumable problem.
8. How to Separate Wear-Related Failure from a Possible Retention Problem
Not every early button loss is caused by overdrilling. A practical field diagnosis should compare the failed insert with the rest of the bit and with other bits from the same batch.
| Pattern | More consistent with | Evidence to collect |
|---|---|---|
| Many buttons heavily flattened before breakage | Delayed grinding / overdrilling | Wear-flat photos, meters to regrind, penetration trend |
| Body deeply washed around multiple inserts | Loss of steel support / formation-related body wear | Side and face photos, rock abrasiveness, flushing condition |
| Multiple inserts cracked after similar service | Fatigue/wear pattern requiring grinding and application review | Close-up macro photos before and after grinding |
| Single complete insert missing very early from an otherwise unworn bit | Localized shock or retention/fit issue | Pocket photos, batch/lot, first-hole history, operating event |
| Same pocket position fails repeatedly across several new bits | Design/retention/application interaction requiring supplier analysis | Several failed samples, serial/batch data, drilling parameters |
Do not destroy the evidence by grinding or welding a newly failed bit before the cause is documented. For an early or repeated button-loss claim, retain at least one failed bit for dimensional or metallurgical analysis if requested by the supplier.
9. Seven-Step Field Troubleshooting Workflow
- Stop and classify the failure. Is the insert chipped, shattered, surface-cracked, or completely missing?
- Inspect all buttons. Compare center, face, and gauge rows. Uniform severe wear points toward maintenance/application causes; an isolated early failure deserves separate analysis.
- Inspect the steel support. Look for body wash, erosion channels, cracks, deformation, or damage around the insert pocket.
- Review the wear interval. Confirm meters or hours since the last regrind and whether the bit was run with large wear flats.
- Review the drilling event. Note stuck steel, redrilled holes, voids, broken ground, sudden jamming, or abnormal rotation/retraction loads.
- Check flushing and operating setup. Record air or water flushing condition, penetration change, feed, rotation behavior, and any unusual heating or recutting.
- Compare the batch. If failure is early, check whether other bits from the same batch and the same position show the same pattern before concluding that the cause is random.
10. Should You Keep Drilling with One Broken or Missing Button?
For production drilling, the safer maintenance decision is to remove a bit with a shattered or missing button and inspect it rather than continuing until the surrounding structure is damaged. The remaining buttons must carry a different load pattern, while a missing insert exposes the pocket and supporting steel to direct rock and cuttings contact. Whether a specific bit can be reconditioned depends on its design, remaining body material, insert condition, and the manufacturer's repair limits.
Do not attempt an improvised field replacement of a carbide insert unless an approved repair process, correct tooling, and inspection criteria are available. For many B2B operations, replacing the bit and preserving the failed sample for analysis costs less than losing drilling time to a second failure in the hole.
11. Procurement Checks That Reduce Repeat Button Failure
- Match the complete drilling system. For DTH bits, the shank and retaining interface must match the hammer exactly; similar outside diameter does not prove compatibility.
- Specify the rock condition. Hardness alone is insufficient. Include abrasiveness, fracture pattern, and whether the formation changes by bench or depth.
- Confirm button and face preferences. Existing standardized spherical/ballistic profiles or convex/concave/flat faces should be stated rather than guessed.
- Send failed-bit evidence. Close-ups of button tops, insert pockets, body wash, gauge row, and the whole face are more useful than one distant photograph.
- Separate wear life from catastrophic failure. “Bit life was short” should be supported by whether the failure was normal wear, loss of gauge, broken carbide, button loss, or body damage.
- Track by batch and drilling condition. A repeat pattern across several bits is much more actionable than a single unexplained failure.
12. What to Send in an RFQ or Failure-Analysis Request
To match a replacement bit or investigate unusual button failure, provide:
- Drilling method: DTH, threaded top hammer, or tapered system
- Hammer/drifter or rock-drill make and model
- Current bit model, shank/thread/taper, and nominal diameter
- Bit face and button shape if known
- Rock type, abrasiveness, fractures/voids, and any foreign-metal risk
- Typical hole diameter, depth, and drilling direction
- Air or water flushing setup and operating pressure/flow information where relevant
- Meters or hours to first grind, number of regrinds, and meters or hours to failure
- Clear face, side, gauge-row, and failed-pocket photographs
- Quantity, destination, and whether the requirement is replacement matching or a new application
PerfoMax currently supplies DTH drill bits selected by hammer shank, hole diameter, face profile, button geometry, flushing arrangement, and rock condition, as well as 32–40 mm tapered button bits for H22 tapered drill rods. For broader selection, review the Drill Bits collection or send a technical RFQ.
13. Frequently Asked Questions
Why do carbide buttons crack even when they are not fully worn?
Cracking can result from cyclic impact fatigue, an unfavorable worn profile, abnormal shock loading, or surface cracking that was not removed during proper regrinding. Diagnose the whole pattern rather than judging only remaining carbide height.
Why does a complete carbide button pop out?
A complete missing insert is different from a chipped button. Inspect the pocket, surrounding steel support, body wash, operating event, and whether the same position fails across multiple bits. Very early repeated loss on otherwise unworn bits warrants supplier analysis.
Can delayed regrinding cause button breakage?
Yes. OEM maintenance guidance links overdrilling with excessive wear flats to broken buttons. Regrinding should restore the intended profile before the bit reaches a severe worn condition, following the bit maker's procedure.[3]
Does harder carbide always last longer?
No. Carbide selection balances hardness and wear resistance with toughness and strength. The best grade depends on the failure mechanism and rock condition, not hardness alone.[1]
What is the most useful evidence for a supplier when buttons fail early?
Send the complete bit face, close-up of the failed insert or empty pocket, side/gauge wear, batch information, drilling system, rock condition, meters/hours to failure, regrinding history, and any unusual drilling event. This lets the supplier distinguish a wear pattern from a localized retention or impact problem.
Technical References
- Sandvik — PowerCarbide® carbide-grade technology
- Sandvik — Down-the-hole bits
- Boart Longyear — Check your buttons: Proven tips for more meters per bit
- Boart Longyear — Percussive Tools catalogue and button-failure troubleshooting
Next Step: Match the Bit to the Failure Pattern, Not Just the Diameter
If your current bits are breaking buttons, losing inserts, or developing repeat surface cracks, do not send only the nominal bit diameter. Send the failed-bit photos, drilling-system connection, rock condition, wear/regrind history, and operating context. Request a PerfoMax compatibility and application review before the next batch is specified.