advanced machining processes
DESCRIPTION
In this document explain about various advanced machining processes and its applications, limitationsTRANSCRIPT
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Principles of Machining
Advanced Machining
Processes
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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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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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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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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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Chemical Machining
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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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Electrochemical Machining
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Electrical Discharge Machining (EDM)
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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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Wire EDM
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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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Laser Beam Machining
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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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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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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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Electron Beam Machining
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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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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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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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Water Jet Machining
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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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Abrasive Jet Machining
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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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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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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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