non conventional maching.pdf

NON – CONVENTIONAL
MACHINING
MACHINING
MANUFACTURING TECHNOLOGY
ME 405

INTRODUCTION TO NON CONVENSIONAL MACHINING
 Many of the recent development in the aerospace and nuclear
engineering industries are partly due to the increasing use of difficult-to-
machine material.
 HASTALLOY, NITRALLOY, WASPALLOY, NIMONICS, CARBIDES, STAINLESS
STEELS, HEAT RESISTING STEELS, etc are considered as difficult to
STEELS, HEAT RESISTING STEELS, etc are considered as difficult to
machine material.
 The conventional machining processes, are inadequate to machine these
materials from the standpoint of economic production.
 Besides machining these materials into complex shapes is difficult, time–
consuming and sometimes impossible.
 Non – traditional machining techniques have emerged to overcome these
difficulties.

 Non- Traditional machining are classified according
to the nature of the energy employed in machining.
THERMAL and ELECTROTHERMAL
CLASSIFICATION OF NON – TRADITIONAL MACHINING
 THERMAL and ELECTROTHERMAL
 CHEMICAL and ELECTROCHEMICAL
 MECHANICAL

ELECTRIC DISCHARGE MACHINING
 The EDM process involves a controlled erosion of electrically
conductive materials by the initiation of rapid and repetitive
spark discharge between the electrode tool (usually
cathode) and workpiece (anode) separated by a small gap
of about 0.01– 0.50 mm known as the spark gap.
 The spark gap is either flooded or immersed under the
dielectric fluid.
TOOL
(CATHODE)
SPARK
GAP
DIELECTRIC
IONISED
FLUID
 The spark discharge is produced by the controlled pulsing
of direct current between the Workpiece and Tool.
 The dielectric fluid in the spark gap is ionized under the
pulsed application of the direct current, thus enabling a
spark discharge to pass between the tool and the
workpiece.
 Each spark produces enough heat to melt and vaporize a
tiny volume of the workpiece material, leaving a small
crater on its surface.
 The energy contained in each spark is discrete and it can be
controlled so that the material removal rate, surface finish
and tolerance can be predicted.
WORKPIECE
(ANODE)
EDM PRINCIPLE

 The electric current is varied
within a wide range, from 0.5 to
400 amp, at 40-300 V dc.
 The pulse duration can be varied
from 2 to 2000 µsec.
The dielectric fliuid is pumped
TOOL
DIELECTRICL
VOLTMETER
FREQUENCY
CONTROL
AMMETER
 The dielectric fliuid is pumped
through the tool or workpiece at
a pressure of 2 kg/cm² or less.
 In some applications the
dielectric fluid is created in
reverse using a vacuum of 0.8 –
0.9 kg/cm².
Reservoir
SET UP FOR EDM
HIGH
PRESSUR
E PUMP
PRESSURE
GAUGE
FILTER
CONTROL
WORK PAN

 DIELECTRIC FLUID:
 Dielectric Fluid is flushed through the spark gap and is supplied through a hole in the
Tool or from external Jets.
 It may be also supplied through holes in the workpiece.
 The dielectric fluid serves as a Spark conductor, concentrating the energy to a narrow
region.
SPARK GENERATOR: Essential function of a Spark Generator are:
 SPARK GENERATOR: Essential function of a Spark Generator are:
 To supply adequate voltage to initiate and maintain the discharge.
 To adjust the discharge current intensely.
 To adjust the discharge duration.
 EDM TOOL (ELECTRODE): Electrode material generally in EDM process are:
 Metallic materials: Electrolytic copper, Tellurium or Chromium copper, Copper Tungsten,
Brass, Tungsten, Steel, Zinc and Zinc alloys, tungsten carbide, aluminium.
 Non- Metallic Materials: Graphite.
 Combination of Metallic and Non-Metallic materials: Copper Graphite.

 METAL REMOVAL RATE:
The metal removal rate is proportional to the working current value. It is generally
described as the volume of metal removed in unit time. The machining rate during
roughing of Steel with a Graphite Electrode and 50 A generator is about 400
mm³/min and with a 400 A generator it is about 4800 mm³/min.
The material removal rate is a function of Current and Pulse Frequency.
EDM PROCESS CHARECTERISTICS
 ACCURACY:
Tolerance value of ± 0.05 mm could be easily achieved by EDM in normal production.
However, by close contact of several variables a tolerance of ± 0.003 mm could be
achieved.
 APPLICATIONS:
EDM is the most widely used machining process among the non-traditional machining
methods. Its chief applications are in the manufacture and reconditioning of PRESS
TOOL and FORGING DIES as well as moulds for injection moulding. EDM process is
also successfully used for producing intricate shaped profiles common to TOOL
ROOMS.

ELECTRO CHEMICAL MACHINING
 Electro Chemical Maching (ECM) is the controlled removal of
metal by anodic dissolution in an electrolytic medium in which the
Workpiece is the anode and the Tool is the Cathode.
 The diagram shows two electrodes which are placed closely with a
‘gap’ of about 0.5 mm and immersed in an elctrolyte which a
solution of sodium chloride (common salt).
 When an electric potential of about 20 V is applied between the
TOOL
WORK
 When an electric potential of about 20 V is applied between the
electrodes, the ions existing in the electrolyte migrate towards the
electrodes.
 Positively charged ions are attracted towards the Cathode and
negatively charged ions are attracted towards Anode. This
initiates the flow of current in the electrolyte.
 The electrolysis process takes place at the cathode librates
hydroxyl ions (negatively charged) and free hydrogen.
 The hydroxyl ions combine with the metal ions of anode to form
insoluble metal hydroxides and the material thus removes from the
anode. This process continues and the TOOL(cathode) reproduces
its shape in the WORKPIECE(anode).
EDM PRINCIPLE
WORK
TOOL

 A typical setup of ECM is shown.
 The electric current is in the order of 50 –
40,000 A at 5 – 30 V dc for a current
density of 20 – 300 A/cm²., across a
gap of 0.05 – 0.7 mm between the
TOOL and the WORKPIECE.
ELECTRO CHEMICAL MACHINING
TOOL and the WORKPIECE.
 The electrolyte flows through this GAP at
a velocity of 30-60 m/sec forced by an
inlet pressure of about 20 kg/cm².
 The temperature of the electrolyte is
maintained around 25 – 60°C.
 Suspended solids are removed from the
electrolyte by settling, centrifuging, or
filtering and the filtered electrolyte is
recalculated for use. A typical setup of ECM is shown.

 MATERIAL REMOVAL RATE: The material removal rate depends mainly on feed rates.
The FEED RATE determines the current passed between the WORK and the TOOL.As the
TOOL approaches the WORK, the length of the curvature current path decreases and the
magnitude of current increases. This lessening of the GAP and increase in the current
continues until the current is just sufficient to remove the metal at a rate corresponding to
the rate of Tool advance.
ECM PROCESS CHARECTERISTICS
 ACCURACY: Under ideal working conditions, ECM process machines with a tolerance of ±
0.02 mm and less. Repeatability of ECM process is also very good. On a good machine,
tolerance can be maintained on a production basis in the range of ± 0.02- 0.04 mm.
 SURFACE FINISH: ECM. Under certain conditions, can produce surface finishes of the
order of 0.4 µm.
 APPLICATION: One of the main applications of ECM is in the aerospace industry to
machine difficult – to – machine material and complex-shaped parts.

 Ultra Sonic Machining (USM) is the process in
which a cutting tool oscillates at high
frequency (about 20,000 cps) in an abrasive
slurry.
 The tool has the same shape as the cavity to
be machined.
ULTRA SONIC MACHINING
be machined.
 The high-speed oscillations of the tool drive
the abrasive grain across a small gap of about
0.02 – 0.10 mm against the Workpiece.
 The impact of the abrasive is uniquely
responsible for the material removal.
 The method is mostly employed to machine
hard and brittle materials which are either
electrically conducting or non-conducting.

 MATERIAL REMOVAL RATE:
 USM can be employed to machine nearly all materials. However, it is not economic to
use USM to machine materials of hardness less than 50 HRC.
 Generally, Stainless Steel, Cobalt-base heat resistant Steels, Germanium, Glass,
Ceramic, Carbide, Quartz and Semiconductors are machined by USM.
 Material Removal Rate per unit time is inversely proportional to the cutting area
of the Tool.
USM PROCESS CHARECTERISTICS
of the Tool.
 SURFACE FINISH:
 The surface finish in USM depends on the size of the abrasive particles, work
materials, tool amplitude and slurry circulation.
 With finer sizes of abrasives, a surface finish of 0.2 – 0.8 µm can be achieved.
 However, the finer abrasives result in slower material removal rate.
 APPLICATION:
USM is particularly suitable for ROUND HOLES and HOLES of any shape for which a
tool can be made. COINING operations for materials such as Glass, Ceramics, etc.
THREADING by appropriately rotating and translating the Workpiece/Tool.

 Abrasive jet Machining (AJM) is the removal of material
from a workpiece by the application of a High-Speed
stream of abrasive particles carried in a gas medium
from a Nozzle.
 The AJM process differs from conventional sand blasting
in that the abrasive is much finer and the process
parameters and the cutting action are carefully controlled.
ABRASIVE JET MACHINING (AJM)
parameters and the cutting action are carefully controlled.
 The process is used chiefly to cut intricate shapes in hard
and brittle materials which are sensitive to heat and have
a tendency to chip easily.
 The process is also used for deburring and cleaning
operations.
 AJM is inherently free from chatter and vibration
problems.
 The cutting action is cool because the carrier gas serves as
a coolant.

EQUIPMENT IN AJM
 A schematic layout of AJM is shown in diagram.
 The filtered gas is supplied under pressure to the mixing chamber containing the abrasive powder and
vibrating at 50c/s .
 The filtered gas mixes with the abrasive particle and is then passed into a connecting hose.
 This abrasive and gas mixture emerges from a small nozzle at high velocity.
 The abrasive powder feed rate is controlled bt the amplitude of vibration of the mixing chamber.
 A pressure regulator controls the gas flow and pressure.
The nozzle is mounted on a fixture.
 The nozzle is mounted on a fixture.
 Either the workpiece or the nozzle is moved by suitable mechanism to control the size and shape of cut.

ABRASIVE MATERIALS:
 Aluminium oxide is the preferred abrasive in the majority of applications.
 Silicon carbide abrasive is also used in certain cases.
 The abrasive particle size is dominant factor in AJM, and best results have
been obtained with a particle size in the range of 10 – 50 µm.
ABRASIVE JET MACHINING (AJM)
been obtained with a particle size in the range of 10 – 50 µm.
 In addition to the above abrasives, dolomite (calcium manganese carbonate)
of 200 grit size is found suitable for light cleaning.
 Sodium Bicarbonate is used for extra fine cleaning operations.
 Glass beads of diameter 0.30 to 0.60 mm are used for light polishing and
deburring.
 Abrasive flow rate influences the material removal rate.
 The maximum material removal rate is obtained with a flow rate of 8-18 g/min.

AJM PROCESS CHARECTERISTICS
 MATERIAL REMOVAL RATE:
A typical material removal rate for abrasive jet machining is 16 mm³/min in cutting glass.
A minimum practical width of cut of about 0.1 mm can be obtained by using a rectangular nozzle
with an orifice of 0.075 x 1.5 mm placed at a distance of 0.08 mm from the work.
 ACCURACY AND SURFACE FINISH:
With closed control of the various parameters a tolerance in the region of ± 0.05mm can be
With closed control of the various parameters a tolerance in the region of ± 0.05mm can be
obtained. On normal production work an accuracy of ± 0.1mm is easily held. Surface finishes
ranges from 0.4 – 1.2 µm in most applications.
 APPLICATION:
Application of the use of AJM process is in the machining of essentially brittle and
heatsensitive materials like Glass, Quartz, Sapphire, Semiconductor materials, Mica and
Ceramics.
AJM process is used in drilling holes, cutting slots, cleaning hard surfaces, cutting fine
lines, deburring, scribing, grooving, polishing and radiusing.
Delicate cleaning, such as removal of smudges from antique documents, is also possible with AJM
process. Because of the accuracy and reliability of AJM process, some research laboratories are
using it to test the abrasion resistance of different materials.

ADVANTAGES OF ABRASIVE JET MACHINING:
 Ability to cut intricate hole shapes in materials of any hardness and brittleness.
 Ability to cut fragile and heat-sensitive materials without damage.
 Low capital cost.
ADVANTAGES AND DISADVANTAGES OF
AJM PROCESS
DISADVANTAGES OF ABRASIVE JET MACHING:
 Material removal rate is slow and hence its application is limited.
 Stray cutting can occur and hence accuracy is not good.
 Embedding of the abrasive in the workpiece surface may occur while maching
softer materials.

LASER BEAM MACHING
 LASER BEAM MACHING (LBM) is a machining
process in which the work material is melted and
vaporised 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 materials.
REFLECTING END
known materials.
 This property of LASER is now being used in
‘machining’ difficult-to-machine materials in
engineering industries.
 LASER is an electromagnetic radiation.
 It produces monochromatic light which is in the
form of an almost collimated beam.
 The word LASER is an acronym for LIGHT
AMPLIFICATION by SIMULATED EMISSION of
RADIATION.
XENON
FLASH LAMP
LENS
PARTIALLY REFLECTING
END
BEAM FOCUSSED
ON WORKPIECE
WORKPIECE
FOCUL
LENGTH
LIGHT
OUTPUT
S
S = MACHINE
SPOT DIAMETER.

PHENOMENON of LBM
 Let us consider that the atoms of a medium (Ruby Crystal Rod) are at ground state Eo.
 When a quantum of energy from a light source (Flash Lamp), is made to fall on this medium
(Ruby Crystal Rod), it caused absorption of energy by the medium (Ruby Crystal Rod).This results
in electrons of the atoms of the medium (Ruby Crystal Rod) to jump to the upper energy level, E1.
The energy level changes from Eo to E1 to Eo. Radiation of photon from the atom takes place
during the change in energy levels.
 This radiation of photons is known as spontaneous emission which is extremely rapid.
 This radiation of photons is known as spontaneous emission which is extremely rapid.
 The radiation of second photon, is exactly on phase with the first photon and it travels in the same
direction. This is known as stimulated radiation.
 To achieve stimulated radiation, a Flash Lamp is kept firing continuously, feeding the atoms into
upper energy level, causing continuous emission of photon.
 The photons move back and forth inside a LASER material, parallel to its axis and continue to
built necessary intensity of the radiation.
 Hence a coherent pulse of light is formed which is known as stimulated energy of Laser.
 This stimulated energy of Laser, has a ability to be focused on a very small area of around 0.05
mm diameter.
 The small area where the LASER BEAM strikes can melt almost any known materials during LBM.

TYPES OF LASER
Many types of LASER exists to produce highly directive beams of Optical or Infrared Radiation.
Two system of LASER used for machining operations:
 Solid State Pulsed Laser:
 LASER material in case are Ruby, Neodymium glass (Nd glass), Neodymiun-Yttrium Aluminium garnet (Nd-
YAG).
 Nd-glass and Nd-YAG are widely used in machining applications. These LASER materials are fabricated
into rods and finished to high optical tolerances.
into rods and finished to high optical tolerances.
 The method used to inject energy into the LASER material is by generating a very intense light flux which
can be absorbed by these LASER materials and then converted into a collimated laser beam.
 The light flux of high intensity is provided by a Xenon Flash Lamp.
 CO2 LASER:
 CO2 LASER system uses three gases, i.e. Nitrogen, Carbon Dioxide and Helium flowing through a glass
discharge tube.
 Nitrogen functions as an intermediary between electrical energy and the vibration energy of CO2
molecules. Helium cools the gas mixture.
 When an electrical discharge energy is generated through these gases, photons are generated when
some of the energy absorbed by CO2 molecules is released. Two properly aligned cavity mirrors direct
the randomly emitted radiations in such a way that a High Intensity LASER Beam is obtained.

PROCESS CHARECTERISTICS OF LBM
 PROCESS CHARECTERISTICS:
A typical Laser system, having an output energy of
20 Joules with a pulse duration of 10ˉ³sec can
produce a peak power of 20,000 W. With a beam
divergence of 0.002 radian, a spot diameter of
0.05 mm exposed to focused laser beam can result
in a power density of 12 x 10 W/cm². A power
REFLECTING
END
in a power density of 12 x 10 W/cm². A power
density of this magnitude is sufficient to melt and
vaporise almost any material including diamond
9
XENON
FLASH
LAMP
LE
NS
PARTIALLY
REFLECTING END
BEAM
FOCUSSED
ON
WORKPIECE
WORKPIE
CE
FOCUL
LENGTH
LIGHT
OUTP
UT
S
S = MACHINE SPOT DIAMETER.
Laser Beam Machining
 MACHINING RATE: Laser can be used for cutting as well for
drilling. The material removal rate in LBM is comparatively low
and is of the order of 4000 mm³/hr.
 ACCURACY: The holes drilled by LASER are not round. In
order to overcome this difficulty the workpiece is rotated as
the hole is Laser-drilled. Other problems associated with Laser
drilling are the taper. Taper 0.5 mm per 10 mm drilled hole is
expected.

ADVANTAGES OF LBM:
 There is direct contact between tool and workpiece.
 Machining of any material including non-metals is possible, irrespective of their hardness and
brittleness.
 Welding, drilling and cutting of areas that are not readily accessible are possible.
 Heat affected zone is small (0.1mm.
LASER BEAM MACHING
DIS-ADVANTAGES OF LBM:
 The overall efficiency of LBM is very low (10-15%).
 The process is limited to thin sheet plates and low material rate.
 The machined holes are nor round and straight.
 Life of the Flash lamp is short.
 Cost is high.
APPLICATION : LBM at present is found suitable only for maching very small holes and cutting
complex profiles like thin, hard materials like ceramics. It is also used for partial cutting and
engraving. Other applications include sheet metal trimming, blanking and resistor trimming.

ELECTRON BEAM MACHINING (EBM)
 ELECTRON BEAM MACHINING (EBM) is a metal removal process in
which a pulsating steam of high-speed electrons produced by a
generator is focused by electrostatic and electromagnetic fields to
concentrate the energy on a very small area of Work.
 As the electrons impinge on the work with velocities exceeding one
half the speed of light, their kinetic energy is transformed into
thermal energy and they vaporize the material locally.
 The process takes place in a vacuum chamber (10 – 10 mm of
mercury) to prevent scattering of the electrons by collision with gas
molecules.
-6
-5

 A typical set – up for Electron Beam Machining is illustrated.
 A stream (beam) of electrons is emitted from the electron gun which is basically a triode and
which consists of:
1) A cathode which is a hot tungsten filament (2500°C) emitting high negative potential
electrons,
2) A Grid Cup, negatively based with respect to the filament, and
3) An anode at ground potential through which the electrons pass.
EQUIPMENT IN ELECTRON BEAM MACHING
3) An anode at ground potential through which the electrons pass.
 The degree of negative bias applied to the grid cup controls the flow of electrons or beam
current, and can also be used to turn the beam on and off.
 The electron passing through the anode and this speed of light by applying 50- 150 KV at
the anode and this speed is maintained till they collide with the workpiece.
 Before the electrons collide with the workpiece, a variable strength electromagnetic field
(lens) is used to re-focus the beam to any desired diameter up to re-focus the Beam to any
desired diameter up to 0.02mm or less.
 This results in an electron beam having a cross-sectional diameter of 0.01 – 0.02 mm with a
power density of 1.5 billion W/cm².
 A built – in microscope with a magnification of 40 on the equipment enables the operator to
accurately locate the beam impact point and observe machining operations.

EQUIPMENT IN ELECTRON BEAM MACHING
ELECTRON
GUN
GRID CUP
VACUUM
CHAMBER
CATHODE (-)
CATHODE
(+)
ELECTRON
EMITTING HOT
TUNGSTEN
ELECTRON
PRINCIPLE OF ELECTRON BEAM MACHINING
WORKPIECE
LOCAL
HEATING,
MELTING,
VAPORISING
BEAM DIRECTED
ELECTROMAGNETICALLY
(+)
ELECTRON
STEAM

PROCESS CHARECTERISTICS OF EBM
 The EBM process is specially suitable for cutting narrow slots and drilling
small-diameter holes.
 The cutting efficiency for EBM rises slightly, reaches a peak and drops rapidly
as the area of cross-sectional of the slot is increased.
 To minimize heating and melting adjacent to the cut, extremely short beam ‘on’
pulses of a few microseconds are used with considerably longer ‘off’ periods
pulses of a few microseconds are used with considerably longer ‘off’ periods
between pulses to permit dissipation of heat and limit the extent of the heat
affected zone.
 The Tungsten can be machined at a rate of 1.5 mm³/sec with one Kilowatt
of power, while Aluminium can be machined at a rate of 4 mm³/sec with the
same power level.
APPLICATION OF EBM:
 EBM is extensively used for welding, their machining application is rare.
 EBM is generally limited to drilling extremely small holes and cutting narrow slots or contours in
thin materials to close tolerances.
The stock removal rate is generally in the region of 1.5 mm³/sec with a penetration rate of about
0.25 mm/sec or faster.

ADVANTAGES AND LIMITATIONS OF EBM
 ADVANTAGES:
EBM has the following advantages:
 Very small holes and slots of high precision in a short time in almost any material
can be made.
 Different shapes of holes, slots and orifices can be machined.
Different shapes of holes, slots and orifices can be machined.
 There is no mechanical contact between the Tool and the Workpiece.
 LIMITATIONS:
The following are the limitations of EBM:
 High cost of equipment.
 Limited applicability (maximum depth of cut is 4 mm)
 Low material removal rate.
 Non – uniformity of holes and taper.
 Requires skilled workmanship.

PLASMA ARC MACHINING (PAM)
 Plasma Arc Machining (PAM) is a material removal process in which the material is
removed by directing a high velocity jet of high temperature (11,000 - 30,000 °C)
ionized gas on the workpiece.
 The relatively narrow plasma jet melts the Workpiece material in its path.
 Because of the high temperature involved, the process can be used on almost all
materials including those which are resistant to oxy-fuel gas cutting.
materials including those which are resistant to oxy-fuel gas cutting.
 Plasma is a mixture of free electrons, positively charged ions and neural atoms.
 It can be obtained by heating a gas to a very high temperature so that it is
partially ionized.
 The plasma torch confines the Plasma forming gas in an arc chamber, and the arc
supplies a large input of electrical energy.
 The central zone of the Plasma reaches a temperature of 15000°C and is
completely ionized.
 Much of the heating of the gas takes place in the constricted region of the nozzle
duct, resulting in high velocity.

EQUIPMENT IN PAM
 The diagram shows atypical set-up of Plasma
Arc Torch.
 A high frequency spark is used to initiate a pilot
arc between the Tungsten electrode (cathode) and
the Copper nozzle (anode), both of which are
water cooled.
 The pilot arc is then cut off, and the external arc
 The pilot arc is then cut off, and the external arc
generates a plasma jet which exists from the
nozzle at near sonic velocity.
 Water injection is sometimes used to assist in
confining the arc, to blast away the scale and to
reduce smoke. Greater nozzle life is reported for
torches of water injection type.
 The PLASMA JET heats the workpiece by
bombardment with electrons and transfer of
energy from high temperature, high-energy gas.
 The heat is effective in cutting thickness of 50
mm.
Selection of gas in PAM:
 Carbon and alloy steel are cut with a
mixture of Nitrogen-Hydrogen, or Compressed
Air.
 Stainless Steel, Aluminium and other non-
ferrous metals are cut with mixture of Argon –
Hydrogen or mixture of Nitrogen-Hydrogen.
 Flow Rate of the gas is 2- 11 m³/hr.

 Cutting rates in PAM are 250-1700 mm/min depending on the thickness
and the material of the workpiece.
 For example, a 25mm thick aluminium plate can be cut at a speed of 750
mm/min , while a 6mm carbon sheet can be cut at 4000 mm/min.
 Surface of metal cut by plasma torch is smoother than surfaces cut by oxy-
PROCESS CHARECTERISTICS IN PAM
 Surface of metal cut by plasma torch is smoother than surfaces cut by oxy-
acetylene flame. The corner radius is of 4mm on thinner plates. The wall of
the cut have a ‘V’ shape with an included angle of 5-10°.
 Accuracy on the width of slots and diameter of holes is from ± 0.8mm on 6-30mm
thick plates and ± 3.0mm on 100-150mm thick plates.
 The depth of heat affected zone depends on the work material, its thickness and
cutting speed. On workpiece of 25mm thickness the heat affected zone is about 4 mm.

APPLICATIONS OF PLASMA ARC MACHINING
 Plasma Arc Machining (PAM) is mainly used to cut Stainless Steel.
 Heavy duty Plasma Torches can cut Stainless Steel with thickness upto
100-125 mm and Aluminium Alloy upto a thickness of 150 mm.
 Metals that cannot be cut by oxy-fuel gas can be cut by PAM.
 Other metals that can be cut by PAM are magnesium, titanium, copper,
nickel, alloy of copper, alloy of nickel.

ADVANTAGES AND LIMITATIONS OF
PLASMA ARC MACHING
 The principal advantage of PAM is that it is almost equally effective on any
metal, regardless of its hardness or refractory nature.
 In Plasma Arc machining (PAM) there is no contact between the tool and
workpiece.
The cutting rates in this are high enough to facilitate this method to be used on
ADVANTAGES
 The cutting rates in this are high enough to facilitate this method to be used on
almost all materials.
LIMITATIONS
 The main disadvantages of this process is the metallurgical alteration of the
surface.
 Thus a secondary machining needs to be performed to remove this surface by
1.5 mm or more.
 Eye shielding and noise protection are necessary for operators in PAM.

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