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Cutting Tools Materials Guide
- 1. Cutting Materials And tools. Cubic Boron Nitride (CBN) Prepared By: Yatinkumar Patel SPECIAL MACHINING METHODS (SMO)
- 2. CONTENT: 1.Different Types of Cutting tools. 2. Requirement of cutting tool. 3. Different types of cutting material. 4. Description of material. 5.About CBN. 6. Comparison of material.
- 3. Different Types of Cutting Tools: Single point tools Multi-point tools Solid Cutting tools Tipped Cutting tools Lathe, shaper, planer, boring Milling, drilling, Grinding, broaching Entire tool body is same material Cutting tool is brazed with tool body.
- 5. CHARACTERISTICS OR PROPERTIES OR REQUIREMENTS OF CUTTING TOOLS: 1. Harder than work piece 2. Hot and red hardness 3. High toughness 4. High thermal conductivity 5. Low coefficient of friction 6. Easy to Fabricate, weld and grind 7. Easily availability and low cost
- 6. Different Types of Cutting materials: Diamond CBN (Cubic Boron Nitride) Ceramic Hard metal HSS (High Speed Steel) Carbon Steel
- 8. Different material description: Carbon Steel: • Carbon content about 0.9 to 1.35%. • Maximum cutting speeds about 8 m/min. • Can be formed into complex shapes for small production Runs. • Limited tool life. Therefore, not suited to mass production. • Suited to hand tools, and wood working. • Low cost. HSS (High speed steel): • special alloy-steel which increases strength, toughness, wear resistance, cutting ability. • can operate at 2 to 3 times higher than HCS tools. • cutting ability at operating temperature to 5670’C. • high hot hardness and wear resistance • Use to manufacture complex shaped tool such as reamers, drills , taps etc.
- 9. Different material description: Hard Metal: • Hard metal tools are used for mass production. • Tools are formed by tungsten, titanium, with carbon in furnace at 14000C. • very high degree of hardness and wear resistance. • Tool can operate at speeds 5 to 6 times higher than HSS. • Tools are expensive, they are available in the form of inserts of different shapes. Ceramic: • Tools capable of withstanding high temperature without loosing hardness. • more wear resistant than cemented carbide tools. • Not use for rough machining work because more brittle and low bending resistance. • coolant is not required. • can be used at very high speed and produce good surface finish.
- 10. Different material description: Diamond: • It is the hardest cutting tool material. • It offers high wear resistance but low shock resistance due to brittleness. • diamond have low coefficient of friction • they are used for high grade superfinishing. • Diamond tools have lowest thermal expansion, high heat conductivity and poor electrical conductivity. • It is brittle in nature. • It gives good surface finish on non-ferrous metals.
- 11. About CBN (Cubic Boron Nitride): • CBN is the hardest material known presently next to diamond. CBN is introduced in 1957. • It is the artificial material produced in the laboratory using high pressure and temperature process. • CBN is made by bonding a 0.5 to 1 mm layer of poly crystalline cubic boron nitride to a carbide substance by sintering under pressure. • The carbide provides shock resistance, while CBN layer provides very high wear resistance and cutting edge strength.
- 12. About CBN (Cubic Boron Nitride): • high hardness and fracture toughness at elevated machining speeds. • It shows excellent performance in grinding any material of high hardness and strength. • The operative speed range for cBN when machining grey cast iron is 300 ~400 m/min Speed ranges for other materials are as follows: Hard cast iron (> 400 BHN) : 80 – 300 m/min Super alloys (> 35 RC) : 80 – 140 m/min Hardened steels (> 45 RC) : 100 – 300 m/min • It is best to use CBN tools with a honed or chamfered edge preparation, especially for interrupted cuts. • CBN tools are also available only in the form of indexable inserts. • CBN is less reactive with such materials as hardened steels, hard-chill cast iron, and nickel- and cobalt based super alloys. • CBN can be used efficiently and economically to machine these difficult-to-machine materials at higher speeds (fivefold) and with a higher removal rate (fivefold) than cemented carbide, and with superior accuracy, finish, and surface integrity.
- 13. CBN (Cubic Boron Nitride): Advantages: • It is the hardest cutting tool material. • Possible to produce sharp edges. • Less expensive then Diamond. • Operating Range is higher than other material. • Suitable for high hardness material. • Easily set-up tool. • It gives good surface finish. Dis-advantages: • High cost.
- 14. Comparison of materials: Sr. No Property Carbon Steel HSS Carbides Ceramics CBN Diamond 1 Hardness (HRA) 60-70 80-85 90-95 95 4000 7000 2 Density (kg/m3) 8000 8500 10000 4000 3500 3500 3 Melting temperature 1000 1300 1400 2000 800 1300 4 Thermal Conductivity (W/mk) 25-30 30-50 50-60 30 13 500-1500 5 Volume of Hard phase 5-7 7-15 70-60 100 95 95 6 Compressive Strength 3500-4000 4000-4500 4500-5500 3000-4000 6900 6900 Typical Property of Tool Material
- 16. Comparison of materials: Sr. no Property Carbon Steel HSS Carbides Ceramics CBN Diamond 1 Hot Hardness Wear Resistance Allowable Cutting Speed Tool Material Cost Low Medium High Very High Extreme Super Extreme 2 Surface Finish Rough Rough Good Very Good Very good Excellent 3 Depth of cut Light to Medium Light to heavy Light to heavy Light to heavy Light to heavy Very light 4 Toughness, Impact Strength, Thermal Sock Resistance, Chipping Resistance Super Extreme Extreme Very high high medium Low 5 Mode of Tool Failure Flank Wear, Crater Wear Flank Wear, Crater Wear Flank Wear, Crater Wear Microchippin g, Gross Fracture Chipping, oxydation Chipping, oxydation
- 18. Hardness versus toughness for some conventional cutting tool materials