This document discusses advanced machining processes, which utilize chemical, electrical, or high-energy beams to remove material as they are needed for difficult-to-machine materials or complex part geometries. It introduces various advanced processes like chemical machining, electrochemical machining, electrical discharge machining, laser beam machining, electron beam machining, and others. These processes allow machining of very hard materials, brittle materials, or parts that are too small, complex, or fragile for traditional machining techniques.

1. 1
Principles of Machining
Advanced Machining
Processes
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2. 2
Types of Advanced Machining Processes
 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
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3. 3
The Need for Advanced Machining
Processes
 Traditional machining processes
• Material removal by mechanical means, such as chip
forming, 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
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4. 4
Typical Parts
 Skin panel for missiles and aircraft
 Turbine blades, nozzles, sheet
metal, small-diameter deep
holes, dies, thick metallic and
nonmetallic parts
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5. 5
Chemical Machining
(Chem Milling)
 Chemicals are used to dissolve
material
 Masks are used to control attack
 Most common use is circuit boards
and plates for printing (Sunday
comics and rotogravure)
 Cutting speed of 0.0025-0.1
mm/minute – very slow
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6. 6
Chemical Machining
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7. 7
Electrochemical 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 airfoil
shapes
 Normally followed by abrasive finishing or laser
peening to remove partially adhering particles
 Works with a wide variety of metals
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8. 8
Electrochemical Machining
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9. 9
Electrical Discharge Machining
(EDM)
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10. 10
Electrical Discharge Machining
 Successive electric arcs melt tiny droplets
from 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” in
depth left on surface
 Secondary process such as chemical
machining used to remove recast layer
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11. 11
Wire EDM
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12. 12
Wire 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
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13. 13
Laser Beam Machining
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14. 14
Laser Beam Machining
 Direct laser beam against surface of
workpiece, as in laser welding
 Successive pulses from laser gun vaporize
tiny bits of workpiece
 Location of laser beam controlled by
computer
 Workpiece need not be conductive
 Cuts are tapered
 Gotta trap overshoot from laser beam
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15. 15
Laser 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 in
blades/vanes for jet engines
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16. 16
Electron Beam Machining
 Workpiece placed in vacuum chamber
 High-voltage electron beam directed
toward workpiece
 Energy of electron beam melts/
vaporizes selected region of workpiece
 Electron beam moved by deflection coils
 Similar process to EB welding
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17. 17
Electron Beam Machining
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18. 18
Plasma Arc Cutting
 Plasma is a stream of ionized gas
 Typical temperatures are very high
 Same process as plasma welding, without filler
metal
 Torch movement controlled by computer
 Power requirements depend on material being
cut, plus depth of cut
 Recast layer is deeper than with other processes
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19. 19
Ultrasonic Machining
 Abrasive slurry flows over top of
workpiece (loose particles)
 Cutting tool vibrated by ultrasonic energy
 Abrasive particles between tool and
workpiece do the machining
 Works well with hard, brittle workpieces
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20. 20
Water Jet Machining
 Narrow jet of water directed, at high
pressure and velocity, against surface of
workpiece
 Jet of water erodes surface of
workpiece, thereby cutting workpiece
 Computer control to achieve shape
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21. 21
Water Jet Machining
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22. 22
Abrasive Jet Machining (Dry)
 Similar to sand blasting, except that a
very narrow jet of air/abrasive particles
achieves localized cutting
 Computer used to position jet
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23. 23
Abrasive Jet Machining
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24. 24
Nanofabrication Methods
 Typically used in the semiconductor
industry
 Combines the lithography technique of
chemical machining with an atomic force
microscope
 May incorporate plasma cutting, reduced
to nano scale
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25. 25
Economics of Advanced Machining
Processes
 High cost of equipment, which typically
includes computer control
 May use hard tooling, soft tooling, or both
 Low production rates
 Can be used with difficult-to-machine
materials
 Highly repeatable
 Typically requires highly skilled operators
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26. 26
Cincinnati Area Advanced Machining
Companies
 Graphel – Wire EDM and Electrodes
 Sermatech-Lehr Precision – Electrochemical
Machining
 Andrews Laser Works – Laser Cutting, Welding and
Drilling
 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
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