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Unit 2 --- ucm
- 1. UNIT- 2 MECHANICAL ENERGY BASEDPROCESSES
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- 4. Arrangement of AbrasiveJet Machining (AJM) .
- 5. Construction details . Gas Used Nitrogen ,Carbon di-oxide , compressed air Abrasive Particles Used Aluminium oxide , Silicon Carbide, Glass Powder , Dolomite and Specially Prepared sodium bicarbonate Nozzle Tungsten Carbide , Synthetic Sapphire (Ceramic)
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- 7. Construction details • Aluminiumoxide (Al2O3 ) - 10 to 50 microns • Silicon Carbide (SiC) - 25 and 50 Microns • Glass Powder - 0.3 to 0.6 mm Abrasive Particle Sizes
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- 9. . • . The Shapeand Size of Cut is controlled by a movement adjusting mechanism given to work piece or Tool Cam Mechanism Pantograph Mechanism
- 10. . . Air Pressure 2 Kg/cm2to 8 Kg/cm2
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- 15. Velocity of Abrasiveparticles
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- 19. Advantages 1. We cancut all kind of materials 2. No heat produced in process , so no thermal damage 3. Very thin and brittle material can be machined 4. Low initial investment 5. Good Surface Finish 6. Intricate holes can be cut in hard and brittle material
- 20. Dis-Advantages 1. Low MRR 2.Soft Material cannot be machined 3. Machining accuracy is poor 4. Nozzle Wear Rate is High 5. Abrasive Powder cannot be reused 6. Embedding of Abrasive particle in work piece is the high damage thing in this process 7. It requires Dust Collection System
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- 27. . . Pump or Intensifier Used toIncrease the water Pressure Up to 1500 – 4000 N / mm2
- 28. . . Accumulator Used to Storethe water Used to avoid water Pulsation
- 29. . . Nozzle Used to Increasethe velocity of water jet Made up of Sintered Diamond, Tungsten Carbide and Synthetic Sapphire Nozzle Exit Diameter 0.05 – 0.35mm Velocity of Water Jet From Nozzle 920 m/s
- 30. . . Regulating Chamber Used to Controlthe flow of water jet to Nozzle
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- 52. . Ultrasonic Generator Used to convertthe current from low frequency to high frequency
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- 54. . Transducer Used to convert Electricalenergy into Mechanical Vibrations
- 55. . Tool Holder Made upof Titanium alloy , Monel , Aluminium, Stainless steel
- 56. . Tool Material Low Carbon Material andStainless steel The tool is brazed, soldered or Fastened mechanically to the transducer through a tool holder
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- 58. Transducer convert the high frequency electricalenergy into Mechanical Vibrations Oscillator convert the Low frequency electrical energy into high frequency electrical energy 20 – 30 HZ Vibrations are transferred to tool material Abrasive Slurry Passed Between the vibrating tool and work piece The refrigeration system used to cool the abrasive slurry to 5 – 6 Degree celcius
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- 62. MAGNETOSTRICTIVE TRANSDUCER . Change inlength is independent of the direction of the magnetic field But depend only on the magnitude of the field and Nature of the material
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- 64. MAGNETOSTRICTIVE TRANSDUCER LT batteryused to heat the filament So electrons are produced Those electrons are accelerated by HT Battery So AC current Produced in the circuit
- 65. So Rod start tovibrate due to magnetostric tive effect This vibrations rod create Ultrasonic Waves , which sent out MAGNETOSTRICTIVE TRANSDUCER
- 66. MAGNETOSTRICTIVE TRANSDUCER The LongitudinalExtension and contraction of the Rod AB produce an EMF in the coil L2
- 67. Resonance Frequency of the oscillatorycircuit Frequency of Vibrating Rod = Resonance will occur when At resonance , the rod vibrates vigorously and ultrasonic waves are produced at high frequencies
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- 70. PIEZOELECTRIC TRANSDUCER Its moreefficient than magnetostrictive transducer The modern USM are of this type.
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- 73. Arrangement of thecircuit
- 74. Working LT batteryused to heat the filament So electrons are produced Those electrons are accelerated by HT Battery So AC current Produced in the circuit This AC current Passes through L1 and L2 and its transferred to Secondary circuit This AC current passed to the plates A and B and it make the Crystal to vibrate due to the principle of inverse piezoelectric effect. The vibrations of crystal creates Ultrasonic waves
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- 76. Advantages – Piezoelectrictransducer Disadvantages – Piezoelectric transducer 1. Piezoelectric quartz is high cost 2. Cutting and shaping of crystal is very complex.
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- 78. STRAIGHT AND TAPERROD AS HORN
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- 82. . 1. Its highsensitive 2. Compact in size
- 83. . 1. Feed rateis high
- 84. MRR MRR Per unittime
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- 86. Factors considered forMRR in USM
- 87. Grain size ofAbrasives
- 88. Abrasive material It Dependon 1.The type of material to be machined 2. Requirement of Surface finish For Machining - Tungsten Carbide - Die Steel Boron Carbide Silicon Carbide Abrasives For Machining - Glass - Ceramics Aluminium oxide
- 89. Concentration of Slurry AbrasiveSlurry = Abrasive Particles + Water
- 90. Amplitude of Vibration MRRincrease with the increase of Amplitude of Vibration
- 91. Frequency MRR increases withthe increase of Ultrasonic wave Frequency
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- 93. Tool Material Lengthy toolcauses overstresses So tool should be short and rigid Process Parameters
- 94. Process Parameters Wear Ratio 1.5: 1 For Tungsten Carbide Work Pieces 100 : 1 For Glass Work Pieces 50 : 1 For Quartz Work Pieces 75 : 1 For Ceramics 1 : 1 For Hardened tool steel Work Pieces
- 95. Abrasive Material and CuttingPower Process Parameters
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- 102. Specifications Voltage = 250V GAP = 0.005 – 0.05 mm Temperature = 10000 degree celcius Spark occur = 10 – 30 micro seconds Current density = 15 – 500 A