Carbide Button Bits

Carbide button bits are an integral component in drilling and machining applications across various industries. This article provides a detailed overview of carbide button bits, their composition, properties, manufacturing process, grades, standards, applications, selection criteria, suppliers, and more.

Overview of Carbide Button Bits

Carbide button bits, also known as button bit cutters, are indexable inserts that are brazed or clamped onto the drill bit body. They are made of tungsten carbide for high wear resistance and are used for drilling holes in rock, masonry, concrete and other hard, abrasive materials.

Some key features of carbide button bits include:

  • Extremely hard cutting surface for drilling hard, brittle materials
  • Indexable inserts can be replaced when worn out instead of the entire drill bit
  • Available in a range of sizes, shapes and grades to suit different drilling needs
  • Advanced geometries and coatings for optimized drill bit performance

Table 1: Types of Carbide Button Bits

TypeDescription
Brazed Button BitsCarbide buttons brazed to a steel shank
Clamped Button BitsCarbide buttons clamped into place by a retainer ring
Underreamer Button BitsFor enlarging boreholes to a bigger diameter
Core Drill Button BitsFor extracting core samples from rocks/concrete
Auger Button BitsFor making deep holes in the ground for pile foundations etc
carbide button bit

Composition of Carbide Button Bits

Carbide button bits gets their wear resistance, hardness and strength from tungsten carbide along with small amounts of other elements used as binders.

Table 2: Chemical Composition

MaterialComposition
Cemented carbide grade94% tungsten carbide (WC) + 6% cobalt binder (Co)
Steel shankIron, carbon, chromium, manganese, silicon etc.
Brazing alloyCopper, zinc, nickel, silver etc.

The exact composition and percentages can vary between different carbide grades and manufacturers. The cobalt binder that holds the WC grains together also plays a key role in strength, fracture toughness and wear properties.

Properties of Carbide Button Cutters

Carbide button inserts exhibit an excellent combination of properties that make them suitable for drilling, cutting and machining extremely hard materials:

Table 3: Properties of Carbide Button Bits

PropertyValueSignificance
Hardness1600 – 2200 VickersAllows cutting of hard materials like rock or concrete
Compressive strength5500-6500 MPaWithstands high pressures during drilling
Transverse rupture strength3000-4800 MPaResistance to fracturing under bending loads
ToughnessUp to 30 MPa√mResistance to crack propagation
Wear resistanceExcellentLong working life before replacement needed
Chemical inertiaHighly inertUnreactive to most chemicals at room temperature
Thermal conductivityLower than steelCan get hot at the cutter edges during machining

The properties can be tuned based on composition, grain size, binder content, manufacturing method and post-treatments.

Manufacturing Process

Carbide button inserts go through a complex series of steps during manufacturing:

Table 4: Typical Manufacturing Process

StepDetails
Milling and blendingBlending of tungsten carbide, cobalt, other powders
CompactionPressing powders into a mold under high pressures
DebindingRemoving binders at approx 300-600°C
Pre-sinteringHeating compacted powders to 1000-1500°C to strengthen
Edge preparationGrinding insert edges into the required geometry
Surface treatmentsCoatings, heat treatment etc. applied to inserts
Brazing/clampingAttaching inserts to the steel drill bit body
FinishingFinal grinding and quality checks before shipment

The powder metallurgy process allows properties and quality to be closely controlled. Customized geometries, coatings and post-treatments further enhance functionality.

Grades of Carbide Button Bits

Carbide grades are classified based on properties like wear resistance, toughness and hardness which are tailored to suit different applications.

Table 5: Standard Grades and Applications

GradeHardnessToughnessTypical Applications
C1-C3HighestLowMachining grey cast iron or non-ferrous metals
C5-C8Very highMediumContinuous cutting of hardened steels or cast iron
C8-C9Extremely highLowInterrupted machining of hardened steels
P10-P50Medium to very highMedium to highRock drilling tools, oil/gas drilling buttons

Custom grades outside standard classifications are also offered by several manufacturers nowadays.

International Standards

Key standards that specify requirements, test methods and quality parameters for indexable carbide inserts relevant to button bits include:

  • ISO 513: Classification and application of hard cutting materials based on hardness
  • ANSI B212.15: Carbide inserts standards in the USA covering geometry, identification, tolerances and testing
  • ISO 1832: Drawings, dimensions and marking conventions for indexable inserts
  • ISO 8249-1: Tool life testing standards for single point turning tools

Reputable carbide button bit manufacturers would comply with these or equivalent national/international standards during manufacturing and quality testing.

Typical Sizes and Dimensions

Carbide button bits are available in a wide range of standard and custom sizes tailored to customer requirements:

Table 6: Standard Button Bit Dimensions

ParameterSize Range
Button diameter8 mm to 150 mm
Button thickness2 mm to 20 mm
Drill diameterUp to 1200 mm
Hole depthUp to 30 m
Number of buttonsUp to 30
Button edge radius0.4 mm to 3 mm
Button center angleUsually 90° or 115°

Applications and Industries

Some leading application areas and industry verticals for carbide button bits include:

Table 7: Applications of Carbide Button Bits

SectorTypical Applications
ConstructionDrilling concrete, masonry, natural stone, tiles
MiningCoal, ore exploration drilling, taking core samples
Oil/gasDownhole button bits for well drilling
QuarryingGranite, limestone, sandstone drilling
GeothermalDeep well drilling through hard rock
Foundation workBored pile construction
ArchaeologyTaking samples from structures or rock

Carbide button bits are indispensable across industries whenever drilling, boring or coring needs to be performed in extra hard materials.

How to Select Carbide Button Bits

Proper selection of composition, size and design is vital for carbide button bits to deliver optimal lifetime and performance.

Table 8: Carbide Button Bit Selection Criteria

ParameterFactors to Consider
Bit diameterSize of hole, depth of borehole/pile
Number of buttonsWeight on bit, drill power, bore diameter
Button sizeSize and position of buttons for even wear and load distribution
Button gradeAbrasion, impact strength needs
Bit typeBased on machine/mounting method – clamped vs brazed
CoatingsUncoated, TiN, TiCN etc. coatings for toughness or lubricity
Coolant compatibilityEnsure carbide grade and coatings withstand coolant

Consult manufacturers providing computer modeling services to simulate button bit performance for optimal selection.

Leading Manufacturers and Suppliers

Some top carbide button bit brands across the globe include:

Table 9: Major Carbide Button Bit Manufacturers

CompanyLocation
Atlas Copco SecorocSweden
PalbitIndia
MinconIreland
Rockmore InternationalUSA
Numa Tool CompanyUSA
DrillcoToolsUK
Rock EyeSouth Africa

Pricing

Carbide button bit pricing depends on size, grade, coatings and order volumes. Typical price range is USD 4 – 12 per insert. Custom bits are more expensive. Volume discounts apply for bulk orders.

carbide button bit
Drill bits used for cutting sit on a table at the 3rd Maintenance Squadron metals fabrication shop on Joint Base Elmendorf-Richardson, Alaska, Jan. 27, 2017. Original public domain image from Flickr

Pros and Cons of Carbide Button Bits

Table 10: Advantages and Limitations

BenefitsDrawbacks
Extremely hard cutting surfaceBrittle materials prone to cracking under impact loads
Higher drilling rates in hard materialsMore expensive than steel button bits
Indexable inserts are replaceableNot recommended for drilling soft formation
Wide range of grades and geometriesRequires rigidity in mounting and machine tool
Advanced coatings resist wear and heatCoolants required for temperature control
Consistent hole diametersHoles may deviate if bits are unevenly worn

FAQs

Q: Are carbide button bits better than roller cone bits?

A: Carbide button bits offer higher penetration rates in hard, abrasive formations like granite or concrete compared to roller cone bits which perform better in softer sedimentary rocks. They have different optimum applications.

Q: How long can carbide button bits last?

A: Carbide grade, drilling application and operating conditions dictate working lifetimes. On average, carbide button bits can drill 50-200 linear feet before requiring replacement whereas roller cone bits may only last 25-100 feet.

Q: Can carbide inserts be resharpened and reused?

A: No, carbide buttons cannot be resharpened after becoming blunt unlike steel bits. The whole insert has to be discarded and replaced with a fresh indexable carbide button for continued drilling.

Q: How are carbide buttons attached to drill bits?

A: Carbide buttons may be brazed into precisely machined grooves on the drill bit steel shank. Alternatively, clamping systems using rings or blocks are used to hold inserts in place for easy indexability.

Q: What drill bits can bore through reinforced concrete?

A: Carbide button bits with ultra hard grades like C6-C8 with TiCN coatings are commonly used for drilling reinforced concrete. Diamond core bits are also suitable but more expensive.

know more Tungsten carbide

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