MFET 4210

 1. Basic Principles  2. Hardware  3. Abrasives  4. Parameters  5. Capabilities  6. Advantages  7. Disadvantages

 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

 Intensifier Pump  Nozzle  Abrasive Delivery System  Catcher  CNC Control

 Intensifier Pump Components  Hydraulic Pump  Pistons  Cylinders  Check valves  Attenuator

 Nozzle  Jewel  Abrasive inlet  Guard  Mixing Tube

 Nozzle  Jewel  Diameter ranges from ”  Usually sapphire, sometimes ruby or diamond

 Nozzle  Abrasive Inlet  Feeds from abrasive feed system  Venturi pulls in abrasive

 Nozzle  Mixing Tube  Abrasive and water mix evenly  Must be exactly in line  Composite carbide

 Abrasive Delivery System  Provide fixed delivery rate  Gravity or air fed

 Catcher  Slows jet of water down  Reduces noise and dust  Catches dust

 CNC Controllers  Traditional control  PCs  Cheaper  Easier to update to newer and faster software

 Usage  ½ to 2 pounds per minute  $0.15 to $0.40 per pound  Types  Garnet  Olivine

 Garnet  Most common at 80 mesh  Naturally occurring mineral  Less dusting  Typical to reuse 2 or 3 times

 Olivine  Cheaper than garnet  Softer than garnet

 Pressure  Nozzle or jewel diameter  Feed or traverse rate  Nozzle standoff distance

 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

 Nozzle Diameter  Large range depending on application  Jet usually ”  Horsepower = 0.58*P*Q  P = pressure in ksi  Q = flow rate in gpm

 Feed Rate  Varies greatly depending on  Type of material  Thickness  Hardness  Quality of cut needed

 Standoff  Usually.010 to 0.200”, up to 1”  Higher distance causes frosting  Eliminated by cutting underwater

 Tolerances  Materials  Geometries  Examples of use

 Tolerances  to ”  Vast majority of industry cuts at ” or more

 Materials  Cuts basically anything  Diamond, some ceramics 6.5” Ti

 Geometry  Stacking parts  5-axis milling

 Geometry  Very thin to very thick cuts  Flat sheets of material 10.25” Tool Steel

 No HAZ  Temp may rise to 120 degrees F  Catch tank and water absorb heat  Very small kerf  ”

 Minimal cutting forces  5 pounds max down force  Very low side forces  Clamping forces are very low  Brittle or fragile work pieces

 Fast and accurate  Minimal fixturing  Omni-directional  Cuts any type of materials  Nonhomogeneous

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

 Lag  Only a factor if finish is important  Very similar to cutting torch lag lines

 Taper  Parts cut with taper  Can be compensated for by software  Increases with nozzle wear

 Less accurate than traditional machining  Very hard materials not very practical application  Traverse rate is so slow, costs add up

 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

 Nozzle wear  Consumable nozzle wears  Causes stray cutting  Increases kerf  Decreases finish quality  Very loud  Reduced if cut underwater

 Machine shops  Artists  Stone, glass, marble  Aerospace  Titanium, Inconel, composites  Rapid prototyping  Universities  Automotive industry  Custom flooring work  Tiles

 Very versatile, powerful technology  Growing use and applications  Constantly getting better and more capable

 Nontraditional Machining Processes, E. J. Weller Nontraditional Machining Processes, E. J. Weller     