What Are Tungsten Carbide Buttons
"Tungsten Carbide Buttons" (also called carbide buttons orcarbide button inserts) are cemented carbide inserts—most commonly WC-Co (tungsten carbide grains in a cobalt binder)—that are pressed/brazed into drill-bit heads and other rock-cutting tools to do the actual work of crushing, chipping, and fracturing rock under repeated impact and rotation.
They’re a core consumable in rock drilling because cemented carbide combines:
● Very high hardness/wear resistance (to slow abrasive rounding)
● High compressive strength (to survive extreme contact stresses)
● Practical toughness (relative to ceramics) (to resist chipping and breakage in impact service)
1. Definition: what a carbide button is
A tungsten carbide button is a compact, engineered insert—typically a cylindrical base with a shaped head—that is mounted into a drill-bit body. Its job is to withstand high contact stress and repeated impact while maintaining a usable shape long enough to meet drilling targets.
2. Where carbide buttons are used
Carbide buttons are widely used wherever a tool must survive impact + abrasion while repeatedly contacting rock:
Top hammer / percussive button bits
● Common in bench drilling, tunneling, and production drilling. Button geometry and grade are chosen based on rock hardness and abrasiveness.
Down-the-hole (DTH) hammer bits
● DTH systems typically use robust button shapes and grades that tolerate high impact while resisting abrasive wear in the flushing stream.
Tricone “TCI” rotary bits
● TCI bits use carbide inserts pressed into cone cutters. Insert shape often varies by formation—softer formations tend to use more aggressive shapes; harder formations emphasize wear stability.
Geotechnical & exploration tools
● Buttons may serve as cutting/contact elements and gage-protection elements to maintain hole diameter and tool life.
A “good” grade and shape in one tool family can be a poor choice in another. The correct button is defined by formation, impact severity, abrasive environment, and bit design constraints.
3. How carbide buttons break rock
Carbide buttons usually do not “slice” rock. Instead, they concentrate load into a small contact area, indent the surface, and initiate cracks. Under repeated impact and rotation, those cracks link and fragments break away.
| What the button must do | What threatens it | What the design optimizes |
| Indent rock repeatedly under impact | Chipping, spalling, breakage from shock and stress concentration | Toughness/strength bias and stable head geometry |
| Maintain geometry under abrasive flow | Wear flats, rounding, gage loss | Hardness/wear resistance + gage-focused design |
| Survive heat and debris in flushing | Thermal cracking, accelerated wear, joint issues | Grade choice + stable installation (press/braze) + good pocket design |
4. Common button shapes and what they’re good at
OEM naming differs, but most button families fall into a few familiar geometry groups. The shape influences penetration, stress distribution, and wear rate.
| Button shape | What it tends to optimize | Typical formation fit | Why |
| Spherical / dome | Wear life and gage holding | Hard and/or abrasive rock | Larger radius spreads stress and resists abrasive flattening |
| Ballistic / parabolic | Higher penetration at acceptable wear | Medium-hard to hard, often less abrasive than “worst case” | More aggressive indentation/crack initiation than spherical shapes |
| Conical / chisel | Fast penetration | Soft to medium formations | Sharper geometry concentrates stress to break softer rock more efficiently |
| Gage-focused variants | Hole diameter stability and side-wear resistance | Abrasive formations; long runs | Gage rows take heavy side wear; design prioritizes wear stability |
5. What “grade” means for carbide buttons
“Grade” is the engineered combination of WC grain size, binder chemistry/content, and microstructural control. In rock tools, grade selection is about balancing wear resistance against impact tolerance.
Key variables that matter most
| Grade variable | What it changes in practice | Common direction of effect (simplified) |
| Binder content (often cobalt %) | Impact tolerance, crack resistance, and overall “survivability” | More binder tends to increase toughness but may reduce hardness (at similar grain size) |
| WC grain size | Wear resistance and edge stability vs. chipping tendency | Finer grains tend to increase hardness/wear resistance; coarser grains tend to improve toughness |
| Binder chemistry (Co-based vs. alternatives) | Performance in corrosive or chemically aggressive environments | Corrosion-resistant binder approaches may be chosen when chemical attack is a major driver |
| Process quality (porosity control, densification, microstructure uniformity) | Consistency, chipping resistance, and reliability | Better densification and defect control usually improves reliability in impact service |
6. How carbide buttons are manufactured
Most carbide buttons are produced via powder metallurgy: powder preparation (WC + binder), pressing to shape, sintering to full density, and finish grinding to meet tight OD requirements.
Why OD grinding and surface integrity matter
Button OD tolerance and surface condition directly affect installation quality (press-fit pocket stability or brazed joint integrity). Poor surface integrity can also become an early crack initiation site under impact loading.
7. Related Langsun Carbide pages
Mining / drilling context
Exploration tools
Geological Exploration Drill Bits
8. FAQ
| Question | Answer |
| What are tungsten carbide buttons? | Tungsten carbide buttons are cemented-carbide inserts (commonly WC–Co) installed into drill-bit bodies to fracture rock under repeated impact and rotation while resisting abrasive wear. |
| Why does button shape matter? | Shape controls how load is distributed into the rock. Spherical shapes usually emphasize wear life in hard/abrasive conditions, while more aggressive shapes can improve penetration in softer formations but may increase chipping risk. |
| What does “grade” mean for carbide buttons? | Grade refers to WC grain size, binder chemistry/content, and microstructural control. These variables shift the balance between wear resistance and impact tolerance—two competing requirements in drilling. |
| Why do buttons chip or break? | Common drivers include impact overload, stress concentration from aggressive geometry, changing contact conditions as the bit wears, and defects or installation issues that allow cracks to start and grow. |
References
Below are the public sources used for definitions, standards, and selection guidance:
● Sandvik Coromant — definition of cemented carbide composition and manufacturing route (pressing/molding + sintering).
● ISO 3738-1 — Rockwell hardness test (HRA) for hardmetals.
● ISO 4499-2 — metallographic measurement of WC grain size.
● ISO 4499-4 — characterization of porosity, carbon defects, and eta-phase in hardmetals.
● ISO 3327 — method for transverse rupture strength of hardmetals.
● Epiroc DTH product catalog — formation-based guidance for ballistic vs spherical buttons.
● General Carbide grade brochure — example hardness ranges across binder % and grain-size classes.
● Journal of the South African Institute of Mining and Metallurgy (1987) — interference fit practice and hot-fitting temperature range for button inserts.
● ISO 857-2 — definition of brazing (filler metal liquidus above 450°C).
● Boart Longyear — example of induction brazing carbide inserts into steel bodies in drilling tools (design dependent).