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Tools

Tools. Manufacturing Processes. Outline. Types of Tools Tool Geometry Cutting Fluids Effects Types Tool Wear Forms Causes Failure Modes Critical Parameters Horsepower Used Operating Temperature Feed and Speed Tool Life. Types of Tools. Tool Geometry. Single Point Tools

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Tools

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  1. Tools Manufacturing Processes

  2. Outline • Types of Tools • Tool Geometry • Cutting Fluids • Effects • Types • Tool Wear • Forms • Causes • Failure Modes • Critical Parameters • Horsepower Used • Operating Temperature • Feed and Speed • Tool Life

  3. Types of Tools

  4. Tool Geometry • Single Point Tools • Multiple Point Tools • Chip Breakers • Effects of Material on Design

  5. Single Point Tools

  6. Multiple Point Tools

  7. Chip Breakers

  8. Important Tool Properties • High hardness • Resistance to abrasion, wear and chipping of the cutting edge • High toughness/impact strength • High hardness at high temperatures • Resistance to bulk deformation • Chemical stability (does not react or bond strongly with the work material • High modulus of elasticity (stiffness) • Consistent tool life • Proper geometry and surface finish

  9. Tool Materials • Carbon and medium-alloy steels • High-speed steels • Cast-cobalt alloys • Carbides • Coated tools • Alumina-based ceramics • Cubic boron nitride • Silicon-nitride-base ceramics • Diamond • Whisker-reinforced materials

  10. Cutting Speeds ofTool Materials

  11. Cutting Fluids • Effects • coolant • lubricant • flushes chips • reduces oxidation of heated surfaces • Types • cutting oils • emulsified oils • chemical fluids

  12. Cutting Fluid Application Flooding • ≥ 3 gallons per minute per tool Misting • atomized fluids • a health hazard (OSHA limit = .2 mg/m3) High Pressure Systems • often applied through the tool

  13. Tool Wear • Forms • crater wear • flank wear • chipping • Causes • abrasion • adhesion • diffusion • plastic deformation

  14. Crater Wear and Flank Wear Crater wear Flank wear

  15. Failure Modes • Fracture • Temperature Failure • Gradual Wear

  16. Critical Parameters • Horsepower Used • Operating Temperature

  17. Horsepower Used Values of Unit Horsepower for Various Work Materials

  18. Operating Temperature

  19. Feed and Speed Speed – the rate at which the tool point moves as it rotates (in a lathe, the rate at which the cutting point on the workpiece rotates) Feed – the rate at which the tool is fed into/along the workpiece

  20. Feed and Speed V = πDN/12 V = surface cutting speed (ft/min) D = diameter of rotating object (in.) N = rotation rate (RPM)

  21. Feed and speed Example: Assume a high-speed steel saw with 100 teeth and a diameter of 6 inches is used to cut aluminum. Determine the proper RPM and feed rate. V (HSS, aluminum) = 550-1000 ft/min [in table] N = 12V/(πD) = 12(550-1000)/(π6) = 350-637 RPM Feed (aluminum, saw) = .006-.01 in/tooth [in table] (.006-.01)100 teeth = .6-1in (.6-1)350 RPM = 210-350 in/min Start with the lowest values. They can be increased so long as the finish is acceptable.

  22. Tool Life F. W. Taylor, 1907 Taylor Tool Life Equation vTn = C vTn= C(Tn ) ref

  23. Cutting Performance How do we know if cutting parameters are optimal? • Surface finish • Tool wear • Chip shape • Sound • Cutting time • Heat

  24. Summary Tools fail slowly with gradual wear or suddenly with fracture Cutting fluids help reduce the effects of wear and temperature failure The materials of the tool and the workpiece affect the tool shape and life Higher cutting speeds increase the operating temperature and decrease tool life It is necessary to calculate proper feed and speed to prevent excessive tool wear

  25. ██████ The End

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