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NONTRADITIONAL (OR)
UNCONVENTIONAL MACHINING
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History of Manufacturing
Manufacturing started during 5000 4000 BC
Wood work,ceramics,stone and metal work
Steel Production 600-800 AD
Industrial Revolution 1750 AD: Machine tools run byinvention of steam engine
Mass Production and Interchangeable Parts
Computer Controlled Machines 1965
CNC,FMS systems
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Historical development of materials
- The Early Days
Period Metals and Casting Forming Process
Egypt ~3100 B.C. to ~300 B.C
Greece ~1100 B.C. to~146 B.C
Roman Empire ~500B.C. to 476 A.D
Middle Ages 476 to1492
Renaissance 14th to
16th centuries
Before 4000B.C
Gold,copper and meteoriticiron
Hammering
4000-3000B.C.
Copper casting,stone andmetal molds,lost waxprocess,silver,lead,tin,bronze
Stamping Jewelry
3000-2000B.C.
Bronze casting Wire by cuttingand drawing, gold
leaf
2000-1000B.C.
Wrought iron,brass
1000-1 B.C. Cast iron, cast steel Stamping of coins
1A.D 1000A.D
Zinc steel Armor,coinage,for ging steel swords
1000-1500A.D.
Blast furnace, typemetals,casting ofbells,pewter
Wire drawing,goldsilver smith work
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Industrial Revolution
1750-1850
1500-1600 A.D. Cast iron cannon, tinplate Water power for metal
working,rolling mill forcoinage
1600-1700 A.D. Permanent mold casting,brassfrom copper and metallic zinc
Rolling(lead,gold,silver)
Shape rolling(lead)
1700-1800 A.D. Malleable cast iron,cruciblesteel
Extrusion (lead pipe),deep drawing,rolling(iron bars androds)
1800-1900 A.D. Centrifugal casting,Bessemer
process,electrolyticaluminum,nickel steels,Babbitt,galvanized steel, powdermetallurgy, tungsten steel, openhearth steel
Steam hammer, steel
rolling,seamless tubepiercing,steel railrolling, continuousrolling , electroplating
Historical development of materials
- The Industrial Revolution
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WW I and WW II 1900-1920A.D.
Tube rolling, hotextrusion
1920-1940A.D.
Die casting Tungsten wire frompowder
1940-1950A.D.
Lost wax for engineeringparts
Extrusion(steel),swaging, powdermetal for engineeringparts
Space Age 1950-1960A.D.
Ceramic mold, nodulariron,semiconductors,continuous casting
Cold extrusion(steel),explosiveforming,thermomechanical treatment
1960-1970 A.D Squeeze casting, singlecrystal turbine blades
Hydrostaticextrusion,electroforming
1970-1980 s Compactedgraphite,vacuumcasting,organically bondedsand,automation ofmolding and pouring, largealuminum castings foraircraft structures rapid
solidification technology
Precisionforging,isothermalforging, super plasticforming,die design byanalytical methods, netshape forming
Historical development of materials
- The Modern Age
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Requirements of a good manufacturing system
Product should meet design requirement
Economical Process
Quality should be built into the system
Should be flexible and responsive to new technology High productivity: Best utilization of man, material,
machine, capital and available resources.
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Steps in Modern Manufacturing
Production drawings;
Instruction manuals
Conceptual design and
evaluation Feasibility study
Designanalysis;codes/standards
review; physical and
analytical models
Prototype production
testing and evaluation
Definition of product need,
marketing information
Material Specification;process
and equipment selection;
safety review
Pilot Production
Production
Inspection and quality
assurance
Packaging; marketing and
sales literature
Product
CAD
CAM and CAPP
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Manufacturing of a Paper Clip
What is the function
How long does it last
How critical is the part
Material Metallic - what type
Non metallic plastic Dimension Diameter of clip
Shape of clip
Method of manufacturing Manual
Automated
Function based design Stress, StrainLife of clip
Stiffness
Style Appearance,Color,Finish
Plating,painting
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AISI 1010,swaged
and cadmium plated
AISI 1020,forging
and chromium plated
AISI 1010, luster finished
coil stock,profile
milled,resistance welded
and chromium plated
formed,welded and plated
AISI 1008, press
formed,welded and plated
Cold drawn medium
carbon steel,( similar to
AISI 1035) bright zincplated
Headed brass,nickel plated
Aluminum permanent mold
casting,machined , polished
and buffed Hardened high-carbonsteel,thread rolled and
chromium plated
AISI 1010,stamped andchromium plated
Case hardened forgingquality steel parts, black
oxide coating
AISI 1040
forging,carburized and
chromium plated
AISI 1010,stamped and
coined and chromium
plated
AISI 1010, stamped and
chromium plated
Aluminum alloy forging,
polished and buffedForged aluminum
tubing(alloy similar to
6063), polished and buffed
AISI 1010 welded tubing,
assembly resistance welded
and electrostatically
painted
AISI 1008,press formed
resistance welded and
painted
AISI 1020 tubing, machine
threaded and painted
Seamless AISI 1020 tubing
swaged tube sectionsbrazed into fork
crown,painted
Manufacturing
of a bicycle
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The requirements that lead to the development of
nontraditional machining.
Very high hardness and strength of the material. (above
400 HB.)
The work piece is too flexible or slender to support the
cutting or grinding forces.
The shape of the part is complex, such as internal and
external profiles, or small diameter holes.
Surface finish or tolerance better than those obtainable
conventional process. Temperature rise or residual stress in the work piece are
undesirable.
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NONTRADITIONAL MACHINING PROCESSES1. Mechanical Energy Processes (USM, WJC, AJM)
- high velocity stream of abrasives or fluid(or both)
2. Electrochemical Processes (ECM)- reverse of electroplating
3. Thermal Processes (EDM, Wire EDM, EBM, LBM,
PAC)
- vaporizing of a small area of work surface
4. Chemical Processes (CHM, Chemical Blanking,
PCM)
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Nontraditional Processes Used
When:1. Material is either very hard, brittle or both;
or material is very ductile: difficult material
2. Part geometry is complex or geometricrequirements impossible with conventional
methods: difficult geometry
3. Need to avoid surface damage or
contamination that often accompanies
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1. Mechanical Energy Processes
Ultrasonic machining (USM)
Water jet cutting (WJC)
Abrasive jet machining (AJM)
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1a) Ultrasonic Machining (USM
& UW)
Abrasives in a slurry are driven at high velocity
against work by a vibrating tool (low amplitude &high frequency)
Tool oscillation is perpendicular to work surface
Abrasives accomplish material removal
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USM Applications
Used only on hard and brittle workmaterials: ceramics, glass, carbides, and
hard metals.
Shapes include non-round holes, holes
along a curved axis
Coining operations - pattern on tool is
imparted to a flat work surface
Produces virtually stress free shapes
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Uses high pressure,high velocity stream of
water directed at work
surface for cutting
1b) Water Jet Cutting(WJC)
5-axes water jet cutting
7 axis for trimming large parts
http://www.jaylenosgarage.com/extras/tools/calypso-waterjet-cutter/http://www.youtube.com/watch?v=GCH2BSfLJ70&feature=player_embeddedhttp://www.youtube.com/watch?v=kRU0RHgS5R4&feature=relatedhttp://www.youtube.com/watch?v=iGQezjZ28N0&feature=relatedhttp://www.youtube.com/watch?v=iGQezjZ28N0&feature=relatedhttp://www.youtube.com/watch?v=kRU0RHgS5R4&feature=relatedhttp://www.youtube.com/watch?v=GCH2BSfLJ70&feature=player_embeddedhttp://www.jaylenosgarage.com/extras/tools/calypso-waterjet-cutter/7/27/2019 105877716 Nontraditional Machining
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WJC Applications
Usually automated using CNC or industrialrobots
Best used to cut narrow slits in flat stock
such as:plastic, textiles, composites, tile,
and cardboard
Not suitable for: brittle materials (e.g., glass)
When used on metals, you need to add to
the water stream: abrasive particles
Smallest kerf width about 0.4 mm for metals,
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WJC Advantages
No crushing or burning of work surface
Minimum material loss
No environmental pollution
Ease of automation
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High velocity gas stream containing
abrasive particles (aka: sand blastingor
bead blasting)
Normally used as a finishing process rather
1c) Abrasive Jet Machining (AJM)
2 Electrochemical Machining
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2. Electrochemical MachiningProcesses
Electrical energyused in combination
with chemical
reactions to removematerial
Reverse of:
electroplating Work material must
be a: conductor
Feature dimensions
Courtesy of AEG-Elotherm-Germany
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Material removal by anodic dissolution,using electrode (tool) in close proximity
to work but separated by a rapidly
flowing electrolyte
Electrochemical Machining (ECM)
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ECM Operation
Material is deplated from anode workpiece(positive pole) and transported to a cathode
tool (negative pole) in an electrolyte bath
Electrolyte flows rapidly between two poles
to carry off deplated material, so it does not:
plate onto the tool Electrode materials: Cu, brass, or stainless
steel
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ECM Applications Die sinking - irregular shapes and
contours for forging dies, plastic molds,
and other tools
Multiple hole drilling - many holes can bedrilled simultaneously with ECM
No burrs created no residual stress
Trimmer et al, APL 2003Schuster et al, Science 2000
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Material Removal Rate of ECM
Based on Faraday's First Law: rate of metaldissolved is proportional to the current
MRR = Ar = CI
whereI= current;A = frontal area of the electrode
(mm2), r = feed rate (mm/s), and = efficiency
coefficient= specific removal rate with work material;
M= atomic weight of metal (kg/mol)
= density of metal (kg/m3),
F= Faraday constant (Coulomb)
n = valency of the ion;
Fn
MC
=
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Equations for ECM (Cont)
Resistance ofElectrode:
gR rA
=
Gap, g
Area, A
ris the resistivity of the
electrolyte fluid (Ohmm)
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Example: ECM through a plate
Aluminum plate, thickness t= 12 mm; Rectangular hole to be cut:
L = 30mm, W= 10mm
Applied current: I= 1200 amps.
Efficiency of 95%,
Determine how long it will take to cut the
hole?
30mm
10mm
Ideal CAl= 3.4410-2 mm3/amps
- other C values in Table 26.1
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Solution:
Frontal Area, A = 30 10 = 300 mm2
Applying MRR = Ar = CI
At 95% efficiency,Feed rate f
r= CI/A
fr= 0.95(3.44 10-2 mm3/amps)(1200 A)/(300
mm2)
fr= 0.131 mm/s
Find machine Time:
3 Thermal Energy Processes
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3. Thermal Energy Processes -Overview
Very high temperatures, but only: locally
Material is removed by: vaporization
Problems and concerns:
Redeposition of vaporized metal
Surface damage and metallurgical damageto the new work surface
In some cases, resulting finish is so poor that
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3. Thermal Energy Processes
Electric discharge machining (EDM)
Electric discharge wire cutting (Wire EDM)
Electron beam machining (EBM)
Laser beam machining (LBM)
Plasma arc cutting or machining (PAC)
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3a) Electric Discharge Machining(EDM)
One of the most widely used nontraditionalprocesses
Shape of finished work is inverse of tool shape
Sparks occur across a small gap between tool andwork
http://www.youtube.com/watch?v=k646HE6MxE4http://www.youtube.com/watch?v=q4FinKsDfwwhttp://www.youtube.com/watch?v=q4FinKsDfwwhttp://www.youtube.com/watch?v=k646HE6MxE47/27/2019 105877716 Nontraditional Machining
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Work Materials in EDM
Work materials must be: electricallyconducting
Hardness and strength of work material
are: not factors
Material removal rate depends primarily on:
melting point of work material
Applications:
Molds and dies for injection molding and
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EDM uses small diameter wire as electrodeto cut a narrow kerf in work similar to a:
bandsaw
3b) Wire EDM
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Material Removal Rate of EDM Weller Equation (Empirical);
Maximum rate: RMR =
whereK= 664
(C1.23mm3/amps);I= discharge
current; Tm = melt temp of work
material
Actual material removal rate:
MRR = vf hwkerf
23.1
mT
KI
While cutting, wire is
continuously advanced
between supply spooland take up spool to:
maintain a constant
diameter
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Wire EDM Applications
Ideal for stamp and diecomponents
Since kerf is so narrow, it
is often possible tofabricate punch and die in
a single cut
Other tools and parts withintricate outline shapes,
such as lathe form tools,
extrusion dies, and flat
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Part loaded inside avacuum chamber
Beam is focused
through electromagnetic
lens, reducing diameter
to as small as 0.025 mm
Material is vaporized in
a very localized area
3c) Electron Beam Machining (EBM)
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EBM Applications
Ideal formicromachining Drilling small diameter holes down to 0.05
mm (0.002 in)
Cutting slots only about 0.025 mm (0.001
in.) wide
Drilling holes with very highdepth to diameter ratios
Ratios greater than 100:1
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Generally usedfor: drilling,
slitting, slotting,
scribing, andmarking
operations
Holes can be
made down to
0.025 mm
3d) Laser Beam Machining (LBM)
) C ( C)
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Uses plasma stream at
very high temperatures
to cut metal 10,000C to
14,000C
Plasma arc generated
between electrode in
torch and anode
workpiece
The plasma flows
through water cooled
nozzle that constricts
3e) Plasma Arc Cutting (PAC)
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Applications of PAC
Most applications of PAC involvecutting offlatmetal sheets and
plates
Hole piercing and cutting along a
defined path
Can be operated by hand held
torch or automated by CNC
Can cut any: electrically
conductivemetal
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4. Chemical Machining (CHM)
CHM Process:
Cleaning to insure uniform etching
Masking a maskant (resist, chemically resistant to
etchant) is applied to portions of work surface not to
be etched
Patterning of maskant
Etching part is immersed in etchant which chemically
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Maskant - Photographic Resist
Method Masking materials contain photosensitive
chemicals
Maskant is applied to work surface (dip coated,
spin coated, or roller coated) and exposed to light
through a negative image of areas to be etched
These areas are then removed using photographic
developing techniques
Remaining areas are vulnerable to etching
Applications:
Small arts on thin stock roduced in hi h uantities
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Material Removal Rate in CHM
Generally indicated as penetration rates, i.e.mm/min.
Penetration rate unaffected by exposed surface
area
Etching occurs downward and under the maskant
In general, d u 2d, Etch Factor: Fe=
(see Table 26.2 pg 637)
u
d
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Chemical Blanking
Uses CHM to cut verythin sheetmetal parts
down to 0.025 mm thick
and/or for intricate
cutting patterns
Conventional punch anddie does not work
because stamping forces
dama e the thin
Parts made by chemical
blanking (photo courtesy
of Buckbee-Mears St.
Paul).
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CHM Possible Part Geometry
Features Very small holes
Holes that are not round
Narrow slots in slabs and plates
Micromachining
Shallow pockets and surface details in flatparts
Special contoured shapes for mold and
die applications
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Chemical Machining (CM)
Oldest nontraditional machining process.
material is removed from a surface by chemicaldissolution using chemical reagents or etchants like
acids and alkaline solutions.
Types of chemical machining
1. chemical MillingBy selectively attacking different areas of
work piece with chemical reagents shallow cavities can
be produced on plates, sheets, forging and extrusion.
2. chemical blankingIt is similar to blanking in sheet metals except
material is removed by chemical dissolution rather than
by shearing. Used in bur free etching of printed circuit
boards, decorative panels etc.
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CHEMICAL MACHINING
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3. Photochemical blanking
This process is effective in blanking fragile work
pieces and materials. Material is removed using
photographic techniques. Applications are electric motor
lamination, flat springs, masks for color television,
printed circuit cards etc.
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ELECTROCHEMICAL MACHINING
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Electrochemical Machining
Reverse of electroplating
An electrolyte acts as a current carrier and high
electrolyte movement in the tool-work-piece gap washes
metal ions away from the work piece (anode) before they
have a chance to plate on to the tool (cathode).
Tool generally made of bronze, copper, brass or
stainless steel.
Electrolyte salt solutions like sodium chloride or sodium
nitrate mixed in water.
Power DC supply of 5-25 V.
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Advantages of ECM
Process leaves a burr free surface. Does not cause any thermal damage to the parts.
Lack of tool force prevents distortion of parts.
Capable of machining complex parts and hard materials
ECM systems are now available as Numerically
Controlled machining centers with capability for high
production, high flexibility and high tolerances.
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ELECTROCHEMICAL GRINDING
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Electrochemical Grinding (ECG)
Combines electrochemical machining with conventional
grinding.
The equipment used is similar to conventional grinder
except that the wheel is a rotating cathode with abrasive
particles. The wheel is metal bonded with diamond or Al
oxide abrasives.
Abrasives serve as insulator between wheel and work
piece. A flow of electrolyte (sodium nitrate) is provided
for electrochemical machining.
Suitable in grinding very hard materials where wheel
wear can be very high in traditional grinding.
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ELECTRICAL DISCHARGE MACHINING
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Electrical discharge machining (EDM)
Based on erosion of metals by spark discharges. EDM system consist of a tool (electrode) and work piece,
connected to a dc power supply and placed in a
dielectric fluid.
when potential difference between tool and work piece ishigh, a transient spark discharges through the fluid,
removing a small amount of metal from the work piece
surface.
This process is repeated with capacitor discharge ratesof 50-500 kHz.
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dielectric fluid mineral oils, kerosene, distilled and
deionized water etc.
role of the dielectric fluid
1. acts as a insulator until the potential is sufficiently
high.
2. acts as a flushing medium and carries away the
debris.
3. also acts as a cooling medium.
Electrodes usually made of graphite.
EDM can be used for die cavities, small diameter deep
holes,turbine blades and various intricate shapes.
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WIRE EDM
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Wire EDM
This process is similar to contour cutting with a bandsaw.
a slow moving wire travels along a prescribed path,
cutting the work piece with discharge sparks.
wire should have sufficient tensile strength and fracturetoughness.
wire is made of brass, copper or tungsten. (about
0.25mm in diameter).
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LASER BEAM MACHINING
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ELCTRON BEAM MACHINING
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Electron beam machining (EBM)
similar to LBM except laser beam is replaced by highvelocity electrons.
when electron beam strikes the work piece surface, heat
is produced and metal is vaporized.
surface finish achieved is better than LBM. Used for very accurate cutting of a wide variety of
metals.
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WATER JET MACHINING
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Water jet machining (WJT)
Water jet acts like a saw and cuts a narrow groove in thematerial.
Pressure level of the jet is about 400MPa.
Advantages
- no heat produced
- cut can be started anywhere without the need forpredrilled holes
- burr produced is minimum
- environmentally safe and friendly manufacturing.
Application used for cutting composites, plastics,fabrics, rubber, wood products etc. Also used in foodprocessing industry.
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ABRASIVE JET MACHINING
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ULTRASONIC MACHINING
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ULTRASONIC MACHINING (UM)
In UM the tip of the tool vibrates at low amplitude and athigh frequency. This vibration transmits a high velocity to
fine abrasive grains between tool and the surface of the
work piece.
material removed by erosion with abrasive particles.
The abrasive grains are usually boron carbides.
This technique is used to cut hard and brittle materials
like ceramics, carbides, glass, precious stones and
hardened steel.