Nonconventional machining

• Abrasive jet machining (AJM)

 Abrasive materials
 Aluminum oxide
 Silicon carbide
 Dolomite (calcium magnesium carbonate)
 Sodium bicarbonate
 Glass beads
 Size of abrasive
 Around 25µm
 Medium
 Air or co2
 Velocity -150 to 300m/sec
 Pressure 2 to 8kg/cm²
 Nozzle – WC with orifice .05-0.2mm³
 Nozzle tip distance 0.25-15mm

 Work material
 Hard and brittle materials like glass, ceramics, mica etc
 Machining operations
 Drilling, cutting, debarring, cleaning

 Advantages of AJM
 Ability to cut intricate hole shapes in hard and brittle materials
 Ability to cut fragile and heat sensitive materials without damage
because there is no heating of working surface
 Low capital cost
 Machining of semiconductors
 Limitations of AJM
 Slow material removal rate
 Low accuracy (0.1mm) due to stray cutting (taper effect)
 Embedding of the abrasive in the w/p surface may occur while
m/cing softer materials
 Abrasive powder can not be refuse
unwanted waste material, especially material that
is regularly thrown away from a house, factory, etc.:By Rushikesh Urunkar JJMCOE

 Taper is also a problem
 Abrasive powder can not be reused
 Machining accuracy is relatively poorer
 It is not suitable for machining ductile materials
 There is always a danger of abrasive particles getting
embedded in the work material, hence cleaning needs to
be necessarily done after the operation

• Applications :
 Cutting slots, thin sections, contouring, drilling, deburring
and for producing intricate shapes in hard and brittle
materials
 It is often used for cleaning and polishing of plastics ,
nylon and teflon components
 Frosting of the interior surface of the glass tubes
 Etching of markings on glass cylinders etc
 Machining of semiconductors

• Electrical discharge machining (EDM)

 Small Spark gap is about 0.01-0.50mm and spark
frequency 200-500 KHz
 The electric current is varied within a wide range from .5
to 400amp at 40-300V dc
 The dielectric fluid is pumped through the tool or w/p at a
pressure of 2kg/cm²
 Material removal rate(max) 5000mm³/min
 Specific power consumption 2-10W/mm³/min

 Tool material
 Brass, copper, graphite, copper tungsten, tungsten carbide
Dielectric fluid
 Hydrocarbon oils, kerosene liquid paraffin, silicon oils,
aqueous solution of ethylene glycol
 Materials that can be machined
 All conducting metals and alloys

Advantages
 The process can be applied to all electrically conducting
metals and alloys irrespective of their melting points,
hardness, toughness or brittleness
 Time of machining is less than conventional machining
 No mechanical stress is present in the process
 Fragile and slender w/ps can be machined without
distortion
 Hard and corrosion resistant surfaces, essentially needed
for die making, can be developed

Limitations
 Machining times are too long
 Excessive tool wear
 High specific power consumption
 Machining heats the w/p considerably and hence causes
change in surface and metallurgical properties
 Profile m/cing of complex contours is not possible at
required tolerances

Applications
 The EDM provides economic advantage for making
stamping tools, wire drawing and extrusion dies, header
dies, forging dies, intricate mould cavities etc
 It has been extremely used for m/cing of exotic materials
used in aerospace industry, refractory metal, hard carbide
and hardenable steels
 Typical EDM applications include
 fine cutting with thread shaped electrode (wire cutting
EDM)
 Drilling of micro-holes
 Thread cutting
 Helical profile milling
 Curved hole drilling

 Electro-chemical machining (ECM)

 ECM is the controlled removal of metal by anodic
dissolution in an electrolytic medium in which the w/p is
the anode and a shaped tool or electrode is the cathode
 Tool material
 Cupper, brass or steel
 Power supply
 Constant voltage DC supply
 Voltage 5-30V dc
 Current 50-40000 Amp

 Electrolyte
 Sodium chloride (common salt)
 Sodium nitrate
 Material removal rate
 1600mm³/min
 Specific power consumption
 7 W/mm³/min (around 150 times more in comparison to
conventional methods )

Advantages of ECM
 The machined work surface is free of stresses
 Burr- free surface
 Reduced tool wear
 No cutting forces are involved in the process
 No thermal damage
 Used for machining difficult to machine materials and
complex shaped parts
 Any good electrically conducting material can be
machined
 High surface finish of order of 0.1 to 2.0 microns
 Very thin sections, such as sheet metals can be easily
m/ned without any damage or distortion

Disadvantages of ECM
 Non-conducting materials can not be machined
 high specific power consumption
 High initial and working cost
 Large floor space is required
 Designing and fabrication of tools is relatively more difficult
 Extremely fine corner radii, say less than 0.2mm, can not be
produce
 Specially designed fixtures are required to hold the w/p in
position, because it may be displaced due to the pressure of the
inflowing electrolyte
 Corrosion and rusting of w/p, m/c tool, fixture etc by
electrolyte is a constant menance

 Applications
 Machining of hard to machine and heat resistant materials
 Machining of blind holes and pockets, such as in forging
dies
 Machining of complicated profiles, such as of jet engine
blades, turbine blades, turbine wheels etc
 Drilling small deep holes, such as in nozzle
 Machining of cavities and holes of irregular shapes
 Deburring of parts

 Laser Beam Machining (LBM)
 LBM – is a machining process in which the work material
is melted and vaporized by means of an intense,
monochromatic beam of light called the laser
 The heat produced in the small area where the laser beam
strikes can melt almost any of the known material
 Light Amplification by Stimulated Emission of Radiation

 Energy level (Ruby LASER)

 Principle :

 Material removal technique
Heating, melting and vaporization
 Tool material
Laser beams in wavelength range of 0.4-0.6 µm
 Power density
As high as 107 W/mm²
 Output energy of laser and its pulse duration
20J, 1milli second
 Peak power
20 KW
 Specific power consumption
1000 W/mm³/min

 Material removal rate
5mm³/min
 Material of work piece
All materials except those with high thermal conductivity
and high reflectivity

 Materials :
 Almost all materials can be cut/drilled with laser (steel
and steel alloys(including those coated with lead, tin, zinc,
nickel, paint or plastic), titanium, tantalum, nickel)
 Non metals which can be cut are – pvc, reinforced plastic,
leather, wood, rubber, wool and cotton,
 Inorganic materials like glass, ceramics, asbestos, mica,
stone, alumina and graphite can also be cut or drilled
 Dynamic balancing of precision rotating components,
such as of watches

 Applications
 Machining very small holes and cutting complex
profiles in thin, hard material like ceramics and
tungsten.
 Application includes sheet metal trimming, blanking
and resistor trimming
 Drilling micro holes (up to 250µm)
 Cutting or engraving patterns on thin films
 The laser beam is effectively used in welding and heat
treatment of material

Engraving patterns on thin films

 There is direct contact b/w tool (laser) and w/p
 Machining of any material including non-metals is possible,
irrespective of their hardness and brittleness
 Welding, drilling and cutting of areas not readily accessible
are possible
 There is no tool wear problem
 Soft materials like rubber and plastics can m/cned
 Extremely small holes can be m/cned i.e drilling micro holes
(up to 250 µm)
 Cutting very narrow slots
 can be effectively used for welding of dissimilar metal as well
Advantages :

 High capital investment needed
 Highly skilled operator are needed
 Very large power consumption
 Low material removal rate
 The process is limited to thin sheet plates(depth limitation)
and where a very small amount of metal removal is
involved
 Can not be effectively used to m/c highly heat conductive
and reflective materials
 The machined holes are not round and straight
 Certain materials like fiber-glass reinforced materials,
phenolics, vinyls etc. cannot be worked by laser as these
materials burn, char and bubble
Disadvantages :

 Life of the flash lamp is short
 Effectively safety procedures are required

 Ultrasonic Machining (USM)

USM, Impact grinding or Ultrasonic grinding
Tapered shank

 Material removal mechanism :
 complex mechanism involving both fracture and plastic
deformation by impact of grains due to vibrating tool
 Tool material :
 Soft steel (generally used), monel metal or stainless steel
 Monel is a group of nickel alloys, primarily composed of
nickel (up to 67%) and copper, with small amounts of
iron, manganese, carbon, and silicon. Stronger than pure
nickel, Monel alloys are resistant to corrosion by many
agents, including rapidly flowing seawater.

 Abrasive :
Silicon carbide, Aluminium oxide, boron carbide or diamond
dust (size:200 to 2000 grit 1000 for finishing)
This process is suitable only for hard and brittle materials like
carbide, glass, ceramics, silicon, precious stones, germanium,
titanium, tungsten, tool steel, die steel, etc
 Medium :
Slurry of water with 30-60% by volume of the abrasives
 Power :
0.2-2.5KW
 Vibrating frequency and amplitude :
15 to 30 kHz as vibrating frequency
0.01 to 0.06 mm as amplitude of vibration

 Cutting rate :
1. Grain size of abrasive
2. Abrasive material
3. Concentration of slurry
4. Amplitude of vibration
5. Frequency
6. Decreases with ratio W/P hard. to tool hard.
 Cooling System :
A refrigerating cooling system is used to cool the abrasive
slurry to a temp 5-6˚c

 Extremely hard and brittle materials can be easily machined
 In machining operations likes drilling, grinding, profiling and
milling operations on all materials both conducting and non
conducting
 The operation is noiseless
 The machined workpieces are free of stresses
 Very high degree of surface finish is obtained
 Metal removal cast is low
 Operation of the equipment is quite safe
 Advantages

 Low metal removal rate
 High rate of tool wear
 Hole depth to diameter ratio of 10:1
 The cost of tool is also high
 Power consumption is quite high
 Difficulties are encountered in machining softer
materials
 In order to maintain an efficient cutting action, the slurry
may have to be replaced periodically
 The size of the cavity that can be machined is limited
 This process does not suit to heavy metal removal
Limitations :

Applications :
 This process is suitable only for hard and brittle materials
like carbide, glass, ceramics, silicon, precious stones,
germanium, titanium, tungsten, tool steel, die steel, etc
 Holes as small as 0.1 mm can be drilled as well as large
holes can be made.
 It is mainly used for drilling, grinding, profiling, coining
and threading operations on all materials both conducting
and non conducting
 Tool and die making , especially wire drawing dies,
extrusion dies and forging dies

 Available in portable 20 W to heavy machines 2000 W
 Stomatology : Enabling a dentist to drill a hole of any
shape on teeth without creating any pain
 Coining operations for materials such as glass, ceramics
etc
 Threading by appropriate rotating and translating the
workpiece or tool.

Water jet machining (WJM)
High-pressure water
Orifice
Abrasive
Focusing tube
Cover

Material removal mechanism :
 High velocity jet made to impinge on workpiece. Jet
pierces the work material and performs desired action.
 Water under pressure from Hydraulic accumulator is passed
through orifice of nozzle to increase its velocity.
 In another type of machine abrasive particles added in high
stream of water jet. (Hydrodynamic Abrasive Jet Machine)
 Orifice of nozzle : Dia. is usually varies from 0.08 to 0.5
 Exit Velocity : 920 m/s
Materials :
 Relatively softer and non metallic materials like paper
boards, wood, plastics, asbestos, rubber, fibreglass, leather.
 All type of ferrous and non ferrous metals and alloys.By Rushikesh Urunkar JJMCOE

Abrasives :
 Silica, Aluminium oxide and garnet
 Grit Sizes : 60, 80, 100 and 120
• Focusing Tube – WC – 0.8 to 2.4 mm
• Pressure – 2500 to 4000 bar
• Abrasive – garnet and olivine - #125 to #60
• Abrasive flow - 0.1 to 1.0 Kg/min
• Stand off distance – 1 to 2 mm
• Machine Impact Angle – 60o to 900
• Traverse Speed – 100 mm/min to 5 m/min
• Depth of Cut – 1 mm to 250 mm
Parameters :

 Almost no heat generated on your part
 There is no tool changing
 Fast setup and programming
 Better edge finish
 No mechanical stresses
 both metal and non-metallic materials
 Are very safe
 Environmentally friendly
 Advantages :

 Limitations :
 Water jet technology cuts slower than laser or other cutting
process
 Reducing material processing productivity
 Higher entry cost than the other cutting machines
 Abrasive material used for cutting harder materials tends to
be quite expensive.

 Paint removal
 Cleaning
 Cutting soft materials
 Cutting frozen meat
 Textile, Leather industry
 Artists
 Surgery
 Aerospace
 Cutting
 Pocket Milling
 Drilling
 Turning
 Nuclear Plant Dismantling
 Application :

Nonconventional machining

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