Advanced Machining Processes


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Advanced Machining Processes

  1. 1. 1Principles of MachiningAdvanced MachiningProcesses
  2. 2. 2Types of Advanced MachiningProcesses Chemical Machining Electrochemical Machining Electrical Discharge Machining Wire EDM Laser Beam Machining Electron Beam Machining Plasma Arc Cutting Ultrasonic Machining Water Jet Machining Abrasive Jet Machining
  3. 3. 3The Need for AdvancedMachining Processes Traditional machining processes• Material removal by mechanical means, such as chipforming, abrasion, or micro-chipping Advanced machining processes• Utilize chemical, electrical, and high-energy beams The following cannot be done by traditional processes:• Workpiece strength and hardness very high, >400HB• Workpiece material too brittle, glass, ceramics, heat-treated alloys• Workpiece too slender and flexible, hard to clamp• Part shape complex, long and small hole• Special surface and dimensional tolerance requirements
  4. 4. 4Typical Parts Skin panel for missiles and aircraft Turbine blades, nozzles, sheet metal,small-diameter deep holes, dies, thickmetallic and nonmetallic parts
  5. 5. 5Chemical Machining(Chem Milling) Chemicals are used to dissolvematerial Masks are used to control attack Most common use is circuit boardsand plates for printing (Sundaycomics and rotogravure) Cutting speed of 0.0025-0.1mm/minute – very slow
  6. 6. 6Chemical Machining
  7. 7. 7Electrochemical Machining(ECM) Combines chemical attack and electrical attack High material removal rate Masking is used to control attack Conforming electrodes are to control shape Commonly used for aircraft parts such as airfoilshapes Normally followed by abrasive finishing or laserpeening to remove partially adhering particles Works with a wide variety of metals
  8. 8. 8Electrochemical Machining
  9. 9. 9Electrical DischargeMachining (EDM)
  10. 10. 10Electrical DischargeMachining Successive electric arcs melt tiny dropletsfrom surface of workpiece Frozen droplets must be flushed away Electrodes are made from graphite,copper or copper-tungsten alloy Material removed from electrode by arc Recast layer of approximately 0.001” indepth left on surface Secondary process such as chemicalmachining used to remove recast layer
  11. 11. 11Wire EDM
  12. 12. 12Wire EDM Uses fine brass wire Wire is used once Easily computer controlled Cutting path must contain straight lines Slow cutting speed Wire breakage is a problem Shallower recast layer than conventional EDM
  13. 13. 13Laser Beam Machining
  14. 14. 14Laser Beam Machining Direct laser beam against surface ofworkpiece, as in laser welding Successive pulses from laser gun vaporizetiny bits of workpiece Location of laser beam controlled bycomputer Workpiece need not be conductive Cuts are tapered Gotta trap overshoot from laser beam
  15. 15. 15Laser Beam Machining (cont) Produces large remelt zone Can produce holes as small as 0.0002”diameter Can produce deep holes Used to produce cooling holes inblades/vanes for jet engines
  16. 16. 16Electron Beam Machining Workpiece placed in vacuum chamber High-voltage electron beam directedtoward workpiece Energy of electron beam melts/vaporizes selected region of workpiece Electron beam moved by deflection coils Similar process to EB welding
  17. 17. 17Electron Beam Machining
  18. 18. 18Plasma Arc Cutting Plasma is a stream of ionized gas Typical temperatures are very high Same process as plasma welding, without fillermetal Torch movement controlled by computer Power requirements depend on material beingcut, plus depth of cut Recast layer is deeper than with other processes
  19. 19. 19Ultrasonic Machining Abrasive slurry flows over top ofworkpiece (loose particles) Cutting tool vibrated by ultrasonic energy Abrasive particles between tool andworkpiece do the machining Works well with hard, brittle workpieces
  20. 20. 20Water Jet Machining Narrow jet of water directed, at highpressure and velocity, against surface ofworkpiece Jet of water erodes surface of workpiece,thereby cutting workpiece Computer control to achieve shape
  21. 21. 21Water Jet Machining
  22. 22. 22Abrasive Jet Machining (Dry) Similar to sand blasting, except that avery narrow jet of air/abrasive particlesachieves localized cutting Computer used to position jet
  23. 23. 23Abrasive Jet Machining
  24. 24. 24Nanofabrication Methods Typically used in the semiconductorindustry Combines the lithography technique ofchemical machining with an atomic forcemicroscope May incorporate plasma cutting, reducedto nano scale
  25. 25. 25Economics of Advanced MachiningProcesses High cost of equipment, which typicallyincludes computer control May use hard tooling, soft tooling, or both Low production rates Can be used with difficult-to-machinematerials Highly repeatable Typically requires highly skilled operators
  26. 26. 26Cincinnati Area AdvancedMachining Companies Graphel – Wire EDM and Electrodes Sermatech-Lehr Precision – ElectrochemicalMachining Andrews Laser Works – Laser Cutting, Welding andDrilling Meyer Tool – Laser Drilling and EDM Barnes Aerospace – EDM Grinding of Honeycomb Cincinnati, Inc – Laser and Plasma Arc Machines Enginetics – EB Welding Elano – Electrochemical Machining