Ajm and wjm
- 2. IntroductionOxygen never should be used
- 3. Mixing chamber vibrates at 50 Hz
- 4. Abrasive velocity 150 to 300 m/s
- 5. Aluminum or Silicon carbide abrasive grains contained in gas or air – for heavy cleaning
- 6. Magnesium carbonate for light cleaning
- 7. Sodium bicarbonate for light cutting AbrasivesApplication dictates the size and the type of abrasive
- 8. Aluminum oxide and silicon carbide- cleaning, cutting, and debarring
- 9. Magnesium carbonate – light cleaning and etching
- 10. Sodium bicarbonate – fine cleaning and cutting of soft material
- 11. Glass beads – Polishing and de-flashing
- 12. Foundry Sand (Garnet is 30% more effective than sand)
- 13. Size of abrasives range from 10 to 50 micrometer
- 14. Powders should be free from silica dust which is hazardous
- 15. re-usability?Process Characteristics Masks are used to control the location of abrasives in restricted areas
- 16. Material Removal Mechanism Tiny Brittle Fracture The material removal rate is mainly dependent on the flow rate and size of abrasives.
- 17. Larger grain sizes produce greater removal rates.AWJMHarder materials such as glass, ceramics, concrete, and tough composites can be cut by adding abrasives to the water jet during abrasive water jet machining
- 18. AWJM cuts 10 times faster than the conventional machining methods of composite materials
- 19. Abrasive water jet is hundreds, if not thousands, of times more powerful than the pure water jetThe Machining System
- 20. The Machining SystemThe basic machining system of AWJM incorporates the following elements: Water delivery Abrasive hopper and feeder Intensifier Filters Mixing chamber Cutting nozzles Catcher
- 22. Ice Jet MachiningDrawback of WJM and AWJM is low efficiency of energy transfer.
- 23. Mixing of water and abrasives limits the minimum jet diameter that can be used
- 24. Abrasives are replaced by ICE
- 25. Low MRR compared to AWJM, however economy and environmental impact is high
- 26. IJM is used in the food, electronic, medical, and space industries where contamination is not permitted Comparison With Other ProcessesAbrasive water jet can machine many materials that laser can not. (Reflective material such Al, copper)
- 27. Abrasive jet do not heat your part therefore no thermal distortion or hardening of material
- 28. Much faster than EDM
- 29. Abrasive jet provide much nicer edge finish without heating a part comparing to flame cutting AJM System Gas (air, Ni, Co2, inert gas) supply at 700-850 KPa
- 30. Jet velocity 100-350 m/s
- 31. Nozzels – WC and Sapphire Process CharacteristicsFor glass-typical MRR are 16 mm3/min
- 32. For metals MRR range from 1.6-4.1 mm3/min
- 33. For hard ceramics MRR are 50% more than for glass ApplicationsDrilling and cutting small sections of glass, ceramics, or hardened metals
- 34. Engraving
- 35. De-burring on metals and plastics
- 36. Frosting glass
- 37. Cutting intricate pattern in hard and brittle materials
- 38. Cleaning oxides from metal surfaces
- 39. Cleaning and trimming of electronic components
- 40. Removing smudges and films from documents and museum artifacts
- 41. Machining of superhard materials
- 42. It is typically used to ut,clean, peen, deburr, deflash, and etch glass, ceramics, or hard metals.ApplicationsDrilling holes, cutting slots, cleaning hardsurfaces, deburring, polishing, and radiusing
- 43. Deburring of cross holes, slots, and threads in small precision parts that require a burr-free finish, such as hydraulic valves, aircraft fuel systems, and medical appliances
- 44. Machining intricate shapes or holes in sensitive, brittle, thin, or difficult-to-machine materials
- 45. Insulation stripping and wire cleaning without affecting the conductor
- 46. Micro-deburring of hypodermic needles
- 47. Frosting glass and trimming of circuit boards, hybrid circuit resistors, capacitors, silicon, and gallium
- 48. Removal of films and delicate cleaning of irregular surfaces because the abrasive stream is able to follow contoursAdvantagesBest suited for machining brittle and heat-sensitive materials like glass, quartz, sapphire, and ceramics.
- 49. The process is used for machining superalloys and refractory materials.
- 50. It is not reactive with any workpiece material.
- 51. No tool changes are required.
- 52. Intricate parts of sharp corners can be machined.
- 53. The machined materials do not experience hardening.
- 54. No initial hole is required for starting the operation as required by wire EDM.
- 55. Material utilization is high.
- 56. It can machine thin materials.LimitationsThe removal rate is slow.
- 57. Stray cutting can’t be avoided
- 58. The tapering effect may occur especially when drilling in metals.
- 59. The abrasive may get impeded in the work surface
- 60. Suitable dust-collecting systems should be provided
- 61. Soft materials can’t be machined by the process
- 62. Silica dust may be a health hazard
- 63. Ordinary shop air should be filtered to remove moisture and oilAdvanced AWJMCAD drawingComputer determines the starting and end points and the sequence of operationsMaterial type and tool offsetModules to optimize the processing CATIA, AUTOCAD, IGES Feed rate and performs cutting
- 64. Application/Process CapabilityNo material restrictions such as electric conductivity, magnetic properties, opaqueness etc. Very suitable for hard and brittle nonmetals such as glass, silicon, tungston and ceramics.
- 65. As the tool is not shaped to conform to the produced feature, it is mainly for cutting or slitting or drilling and not for profiling or surface generation.
- 66. It is however used for polishing and etching. Very low MRR in polishing, i.e., < 0.015 cm3/min.
- 67. An entry hole is required.Water Jet Machining
- 68. Water Jet MachiningMACH-3 VelocityThe hydraulic pump is powered from a 30- kilowatt (kW) electric motor and supplies oil at pressures as high as 117 bars in order to drive a reciprocating plunger pump termed an intensifier (4 bar to 3800 bar).
- 69. Water Jet MachiningThe accumulator maintains the continuous flow of the high- pressure water and eliminates pressure fluctuations. It relies on the compressibility of water (12 percent at 3800 bar) in order to maintain a uniform discharge pressure and water jet velocity, when the intensifier piston changes its direction.
- 71. Operating SummaryFluid Type : Water or water with additives Additive : Glycerin, Polyethylene Oxide or long chain polymer Pressure : 100 to 1000 MPa Jet Velocity : 300 to 1000 m/min Power : Up to 40 Kw Metal Removal Rate : 0.5 mm3/s for metals and alloys, 20 mm3/s for Elastomers Nozzle Material : Hardened steel, WC synthetic sapphire
- 72. Water Jet Cutting Rates
- 73. AdvantagesIt has multidirectional cutting capacity.
- 74. No heat is produced.
- 75. Cuts can be started at any location without the need for predrilled holes.
- 76. Wetting of the workpiece material is minimal.
- 77. There is no deflection to the rest of the workpiece.
- 78. The burr produced is minimal.
- 79. The tool does not wear and, therefore, does not need sharpening.
- 80. The process is environmentally safe.
- 81. Hazardous airborne dust contamination and waste disposal problems that are common when using other cleaning methods are eliminated.Advantages There is multiple head processing.
- 82. Simple fixturing eliminates costly and complicated tooling, which reduces turnaround time and lowers the cost.
- 83. Grinding and polishing are eliminated, reducing secondary operation costs.
- 84. The narrow kerf allows tight nesting when multiple parts are cut from a single blank.
- 85. It is ideal for roughing out material for near net shape.
- 86. It is ideal for laser reflective materials such as copper and aluminum.
- 87. It allows for more accurate cutting of soft material.
- 88. It cuts through very thick material such as 383 mm in titanium and 307 mm in Inconel.Disadvantages Low MRR
- 89. Stray cutting
- 91. Taper on cut geometryEND