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Abrasive water jet machining

Abrasive water jet machining. MFET 4210. Topics for Today. 1. Basic Principles 2. Hardware 3. Abrasives 4. Parameters 5. Capabilities 6. Advantages 7. Disadvantages. 1. Basic Principles. How does it work? High pressure water with abrasive eroding material

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Abrasive water jet machining

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  1. Abrasive water jet machining MFET 4210

  2. Topics for Today • 1. Basic Principles • 2. Hardware • 3. Abrasives • 4. Parameters • 5. Capabilities • 6. Advantages • 7. Disadvantages

  3. 1. Basic Principles • How does it work? • High pressure water with abrasive eroding material • Small diameter orifice or “jewel” to focus energy • Erosion of material • Jet of abrasive and water • 20,000 – 90,000 psi • Up to 600 mph

  4. 2. Hardware • Intensifier Pump • Nozzle • Abrasive Delivery System • Catcher • CNC Control

  5. Hardware • Intensifier Pump Components • Hydraulic Pump • Pistons • Cylinders • Check valves • Attenuator

  6. Hardware Delivery System • Nozzle • Jewel • Abrasive inlet • Guard • Mixing Tube

  7. Hardware Delivery System • Nozzle • Jewel • Diameter ranges from .005 - .020” • Usually sapphire, sometimes ruby or diamond

  8. Hardware Delivery System • Nozzle • Abrasive Inlet • Feeds from abrasive feed system • Venturi pulls in abrasive

  9. Hardware Delivery System • Nozzle • Mixing Tube • Abrasive and water mix evenly • Must be exactly in line • Composite carbide

  10. Hardware • Abrasive Delivery System • Provide fixed delivery rate • Gravity or air fed

  11. Hardware • Catcher • Slows jet of water down • Reduces noise and dust • Catches dust

  12. Hardware • CNC Controllers • Traditional control • PCs • Cheaper • Easier to update to newer and faster software

  13. 3. Abrasives • Usage • ½ to 2 pounds per minute • $0.15 to $0.40 per pound • Types • Garnet • Olivine

  14. Abrasives • Garnet • Most common at 80 mesh • Naturally occurring mineral • Less dusting • Typical to reuse 2 or 3 times

  15. Abrasives • Olivine • Cheaper than garnet • Softer than garnet

  16. 4. Parameters • Pressure • Nozzle or jewel diameter • Feed or traverse rate • Nozzle standoff distance

  17. Parameters • Pressure • Ranges from 20-90,000 psi • Less than 60,000 psi most common • Higher pressure for harder materials and thicker cuts • Harder on equipment

  18. Parameters • Nozzle Diameter • Large range depending on application • Jet usually .020-.050” • Horsepower = 0.58*P*Q • P = pressure in ksi • Q = flow rate in gpm

  19. Parameters • Feed Rate • Varies greatly depending on • Type of material • Thickness • Hardness • Quality of cut needed

  20. Parameters • Standoff • Usually .010 to 0.200”, up to 1” • Higher distance causes frosting • Eliminated by cutting underwater

  21. 5. Capabilities • Tolerances • Materials • Geometries • Examples of use

  22. Capabilities • Tolerances • +-.004 to +-.008” • Vast majority of industry cuts at +-.010” or more

  23. Capabilities • Materials • Cuts basically anything • Diamond, some ceramics • 6.5” Ti

  24. Capabilities • Geometry • Stacking parts • 5-axis milling

  25. Capabilities • Geometry • Very thin to very thick cuts • Flat sheets of material • 10.25” Tool Steel

  26. 6. Avantages • No HAZ • Temp may rise to 120 degrees F • Catch tank and water absorb heat • Very small kerf • .020-.050”

  27. Avantages • Minimal cutting forces • 5 pounds max down force • Very low side forces • Clamping forces are very low • Brittle or fragile work pieces

  28. Avantages • Fast and accurate • Minimal fixturing • Omni-directional • Cuts any type of materials • Nonhomogeneous

  29. Avantages • No tools to sharpen, only “tool” is the nozzle • Environmentally friendly • Garnet can be dumped in landfill • Water can be filtered and reused

  30. 7. Disadvantages • Lag • Only a factor if finish is important • Very similar to cutting torch lag lines

  31. Disadvantages • Taper • Parts cut with taper • Can be compensated for by software • Increases with nozzle wear

  32. Disadvantages • Less accurate than traditional machining • Very hard materials not very practical application • Traverse rate is so slow, costs add up

  33. Disadvantages • Can delaminate some materials • Fiberglass, some composites • Preventable with pilot hole from drill • Cost • Setup ranges from $20,000-$300,000 • Average machine runs $150,000 • Thickness of cut • Price increases dramatically for >2” metal cuts

  34. Disadvantages • Nozzle wear • Consumable nozzle wears • Causes stray cutting • Increases kerf • Decreases finish quality • Very loud • Reduced if cut underwater

  35. Applications • Machine shops • Artists • Stone, glass, marble • Aerospace • Titanium, Inconel, composites • Rapid prototyping • Universities • Automotive industry • Custom flooring work • Tiles

  36. Summary • Very versatile, powerful technology • Growing use and applications • Constantly getting better and more capable

  37. Sources • Nontraditional Machining Processes, E. J. Weller • http://www.jetedge.com • http://waterjets.org/ • http://www.h2ocut.com/ • http://www.universalminerals.com/ • http://www.flowcorp.com/

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