CGS Tool Blog Carbide Cutting Tool Grades

A detailed look at various grades of carbide cutting tools, focusing on their composition, properties, and applications:1. Cemented CarbideComposition:Made from tungsten carbide (WC) particles bonded with a metallic binder, typically cobalt (Co) or nickel (Ni).Common ratio: 70-97% tungsten carbide and 3-30% cobalt.Properties:Hardness: High hardness, excellent wear resistance.Toughness: Good toughness due to cobalt binder, making it resistant to chipping and cracking.Thermal Conductivity: Good heat dissipation, enabling higher cutting speeds.Strength: Strong under compressive loads but less resistant to tensile stress.Applications:General-purpose machining (e.g., steel, stainless steel).Heavy-duty cutting operations.High-speed machining due to excellent thermal stability.2. Ceramic Cutting ToolsComposition:Primarily made of aluminum oxide (Al₂O₃) or silicon nitride (Si₃N₄).May be reinforced with zirconia (ZrO₂) or mixed with titanium carbide (TiC).Properties:Hardness: Extremely high hardness, even at elevated temperatures.Toughness: Lower than cemented carbide, making it prone to chipping.Thermal Resistance: Excellent high-temperature stability and oxidation resistance.Chemical Stability: Resistant to chemical reactions with metals.Applications:High-speed finishing operations.Machining hard materials like cast iron and high-strength alloys.Not suitable for interrupted cuts due to brittleness.3. Cermet (Ceramic-Metal Composite)Composition:Made from ceramic particles (e.g., TiC or TiN) bonded with metallic materials (e.g., nickel or cobalt).Properties:Hardness: Intermediate between ceramics and cemented carbides.Toughness: Higher toughness than ceramics but less than cemented carbide.Thermal Conductivity: Moderate, reducing thermal shock resistance.Wear Resistance: High resistance to wear, especially in finishing applications.Applications:Finishing and semi-finishing of steel and stainless steel.Applications requiring a smooth surface finish.Not ideal for roughing or interrupted cuts.4. Polycrystalline Diamond (PCD)Composition:Sintered layer of diamond particles bonded to a carbide substrate.Properties:Hardness: Extremely high hardness, second only to natural diamond.Wear Resistance: Exceptional wear resistance, especially for abrasive materials.Thermal Conductivity: Excellent heat dissipation, reducing tool wear.Chemical Reactivity: Poor performance with ferrous materials due to carbon diffusion.Applications:Machining non-ferrous materials (e.g., aluminum, copper, composites).High-precision applications requiring a superior finish.Not suitable for cutting steel or high-temperature alloys.5. Cubic Boron Nitride (CBN)Composition:Cubic form of boron nitride bonded to a carbide substrate.Properties:Hardness: Very high, second only to diamond.Thermal Resistance: Outstanding thermal stability.Wear Resistance: Excellent for cutting hard and abrasive materials.Chemical Stability: Works well with ferrous materials, unlike PCD.Applications:Hard turning and milling of hardened steel.Cutting high-temperature alloys.High-speed machining with long tool life.Summary Comparison TableGradeHardnessToughnessThermal StabilityWear ResistanceKey ApplicationsCemented CarbideHighHighGoodHighGeneral-purpose machining; high-speed cutsCeramicVery HighLowExcellentHighHigh-speed finishing; cast iron machiningCermetMediumModerateGoodHighFinishing/semi-finishing of steelPCDExtremeModerateExcellentExceptionalNon-ferrous machining; precision cuttingCBNVery HighModerateOutstandingHighHardened steel; high-temp alloysKey Considerations for SelectionMaterial to be Machined: Choose PCD for non-ferrous, CBN for hardened steels, ceramics for cast iron, etc.Type of Machining: For roughing, cemented carbides are better. For finishing, cermets or ceramics excel.Cutting Speed and Temperature: High-speed machining benefits from ceramics or PCD.Cost and Tool Life: PCD and CBN are expensive but offer exceptional tool life.