Laser Cutting 2020

………………,,…….LASER CUTTING

……………,,…….A SEMINAR REPORT

.......................................,,,......Submitted to

………,,,…SSM COLLEGE OF ENGINEERING

……………………………,,…...by

……………………..….NIHAN ALTAF

…………..In partial fulfillment for the award of the degree

………………………………..……of

…………….BACHELOR OF ENGINEERING

………………………..……in

………………MECHANICAL ENGINEERING

..............DEPARTMENT OF MECHANICAL ENGINEERING

……………….SSM COLLEGE OF ENGINEERING

……………………..DIVAR, PARIHASPORA

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SSM COLLEGE OF ENGINEERING

DIVAR PARIHASPORA

CERTIFICATE
This is to certify that the Dissertation entitled Laser Cutting is a bonafide record of
independent research work done by Ms.NIHAN ALTAF (Reg. No.4780 -SME -2017) under
my supervision and submitted to SSM COLLEGE OF ENGINEERING for seminar
presentation of BACHELORS OF ENGINEERING IN MECHANICAL ENGINEERING.

Er. Mohammad Rafiq Er. Mohammad Nayeem

seminar coordinator HOD

Mechanical Department Mechanical Department

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DECLARATION

I, Nihan a student of B.E in Mechanical Engineering in SSM College, Parihaspora

Pattan, would like to declare that the dissertation entitled laser cutting submitted by me for

seminar presentation of BACHELORS OF ENGINEERING IN SSM College Of Engineering

is my original work.

Signature of student

Nihan

B.E Mechanical

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ACKNOWLEDGEMENT

The seminar report on “laser cutting ” is the outcome of guidance, moral support and

devotion bestowed on me throughout my work. For this, I acknowledge and express my

profound sense of gratitude and thanks to everybody who have been a source of inspiration

during the seminar preparation.

First and foremost I offer my sincere phrases of thanks to Mr. MOHAMMAD RAFIQ

(Assistant professor of SSM College of Engineering) for providing help,whenever needed.

If I can say in words I must at the outset tender my intimacy for receipt of affectionate care

to SSM College of Engineering for providing such a stimulating atmosphere and wonderful

work environment.

Nihan

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LASER CUTTING

ABSTRACT

Laser cutting is one of the most widely used thermal energy based non-contact type advance

machining process which can be applied for almost whole range of materials. The width of

laser cut or kerf, quality of the cut edges and the operating cost are affected by laser power,

cutting speed, assist gas pressure, nozzle diameter and focus point position as well as the

work-piece material. This report aims at presenting the state of the art in the field of laser

cutting of various engineering materials. This paper reviews the research work carried out so

far in the area of laser cutting process and also the experimental and theoretical studies on the

influence of the process parameters like power, cutting speed, gas pressure, focus position etc

on surface roughness, kerf width and heat affected zone (HAZ).

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TABLE OF CONTENTS
CERTIFICATE………………………………………….….….….ii

DECLARATION………………………………………..….….….iii

ACKNOWLEDGEMENT…………………………..……………iv

ABSTRACT………………………………………..……….……...v

CHAPTER 1: INTRODUCTION
1.1 LASER……………………………………………………..………....1

1.2 LASER CUTTING ……………………………………..….…....…....2

CHAPTER 2: LASER CUTTING PROCESS

2.1 WORKING PRINCIPLE ………………………………...…..…...…4

2.2 PROCESS PARAMETERS ………………………….….......................4

2.2.1 SURFACE ROUGHNESS…………………………………….…….…5

2.2.2 KERF WIDHTNESS……………………………………………......…6

2.2.3 LASER POWER …………………………………………………..….7

2.2.4 PULSE FREQUENCY …………………………………………....…..7

2.2.5 TYPE OF GAS …………………………………………………..…….7

2.2.6 PRESSSURE OF GAS…………………………………………….…....8

2.2.7 NOZZLE ALINGNMENT …………………………………….……...8

2.2.8 NOZZLE DISTANCE …………………………………………….….9

2.2.9 CUTTING SPEED…………………………………………….…//.…10

2.2.10 ACCELERATION ……………………………………………//..….11

2.2.11 MATERIAL THICKNESS………………………………………….11

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2.2.12 WORK PIECE SURFACE ………………………………………… ..11

2.2.13 FOCAL POSITION RELATIVE TO SURFACE …………… .....….12

CHAPTER 3 : TYPES OF LASERS

3.1 CO2 LASER CUTTING …………………………………… ..14

3.2 FIBER LASER ………………………………………………..15

3.3 Nd:YAG/Nd:YVO LASERS ………………………………16

CHAPTER 4 : APPLICATION OF LASER CUTTING

4.1 LASER CUTTING OF METALS ……………………………18

4.2 CUTTING OF REFLECTIVE METALS…………………….18

4.3 USE IN SURGERY ………………………………………......18

4.4 CUTTING OF SILICON ……………………………………..19

4.5 CUTTING OF CERAMICS ……………………………….….19

4.6 LASER MARKING AND LASER ENGRAVING ……..…19

4.7 CUTTING OF OTHER NON METALS …………………….19

CONCLUSION………………………………………..…….…..21

REFERENCES……………………………………………...…..22

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TABLE OF FIGURES
FIGURE 1: LASER DEVICE ………………………………..…...2

FIGURE 2 :BASIC LASER CUTTING PROCESS…………...….3

FIGURE 3 :SCHEMATIC DIAGRAM OF LASER BEAM….…4

FIGURE 4 :SURFACE ROUGHNESS V/S POWER…………...5

FIGURE 5: SURFACE ROUGHNESS V/S ASSIST GAS.............6

FIGURE 6: KERF WIDTH V/S POWER……………...……….....6

FIGURE 7: KERF WIDTH V/S CUTTING SPEED …………......6

FIGURE 8: KERF WIDTH V/S ASSIST GAS…………………....7

FIGURE 9: NOZZLE ALIGNMNET …………………………......9

FIGURE 10: NOZZLE DIA AND STAND OFF DISTANCE…...10

FIGURE 11:CUTTING SPEED VS MATERIAL………………....11

FIGURE 12 : FOCAL LENGTH…………………………….....…13

FIGURE 13: FOCUS POINT …………………………………..…13

FIGURE 14 : SCHEMATIC DIAGRAM OF CO2 LASER ….…14

FIGURE 15: FIBER MODULE …………………………….……16

FIGURE 16: a) SCHEMATIC OF THE Nd:YAG SETUP……....17

b) STRUCTURE OF THE Nd:YAG/Cr:YAG…..….17

c) SCHEMATIC OF THE Nd:YVO LASER …....…17

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1: INTRODUCTION

1.1 LASER.

A laser is a device that emits light through a process called stimulated emission. The term
laser is acronym for light amplification by stimulated emission of radiation. A laser is
effectively a machine that makes billions of atoms pump out trillions of photons all at once, so
they line up to form a really concentrated light beam

The first ever laser was constructed in 1960 by Theorde Maiman based on earlier work by
Charles.H.Townes.

Laser is very different from normal light. Laser light has the following properties :

 It is monochromatic
 It is coherent
 It is directional

To make these properties occur, it takes something called stimulated emission of photons. The
photons that any atom releases has a certain wavelength which is dependent on the energy
difference between the exited and the ground state. If this photon encounters another atom
that has an electron in the same excited state, stimulated emission can occur.

The another key to laser is a pair of mirrors one at each end of a lasing medium. Photons with
a specific wavelength and phase are reflected back and forth through the lasing medium. In
the process they stimulate other electrons to make a downward energy jump and can cause
emission of more photons of the same wavelength and phase. A cascade effect occurs and
soon we get many photons of the same wavelength and phase . the mirror at one end of the
laser is half silvered ie it reflects some light and lets sme light pass through . the light that
makes it through is the LASER light . Lasers produce such intense and precisely focused
energy that they can cut through metals, ceramic, plastics etc. the pin point precision of laser
makes it suitable for wielding, medical industries [eg laser surgery to correct short
sightedness].

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Figure 1 laser device.

1.2 LASER CUTTING.

Laser cutting is a thermal based non-contact process capable of cutting complex contour on
materials with high degree of precision and accuracy. It involves process of heating, melting
and evaporation of material in a small well defined area and capable of cutting almost all
materials. The word LASER stands for Light Amplification by Simulated Emission of
Radiation. Laser has a wide range of applications, ranging from military weapons to medical
instruments. In industries laser is used as an unconventional method for cutting and welding.
The main advantage of laser cutting is that, it is a non-contact operative method from which a
good precise cutting of complicated shapes can be achieved. Also laser can be used to cut
variety of materials like wood, ceramic, rubber, plastic and certain metals. Extensive research
work is being done in laser cutting for improving the quality of cut. The quality of cut
depends upon many control factors or parameters such as laser beam parameters (laser power,
pulse width, pulse frequency, modes of operation, pulse energy, wavelength, and focal
position); material parameters (type, optical and thermal properties, and thickness); assist gas
parameters (type and pressure) and processing parameters (cutting speed). The laser cutting is
a very complex and nonlinear process due to involvement of many process parameters. Many
researchers have investigated the effect of these process parameters on different quality
characteristics such as material removal rate (MRR), kerf quality characteristics (kerf width,
kerf deviation and kerf taper), Surface quality (cut edge surface roughness, surface
morphology), metallurgical quality characteristics (recast layer, heat affected zone, oxide

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layer and dross inclusions) and mechanical properties (hardness, strength).

Figure 2 Basic laser cutting process

Laser cutting offers several advantages over conventional cutting methods such as plasma
cutting. The advantages of laser cutting include high productivity thanks to the high cutting
speeds, narrow kerf width (minimum material lost), straight cut edges, low roughness of cut
surfaces, minimum metallurgical distortions, and easy integration. In the early 1980’s, laser
cutting had a limited application, being mostly used in high technology industries such as
aerospace and the available commercial equipment could only cut light sheet (1- 2 mm)
because of their limited power output. Laser technology has continued to develop over the
years and now many types of lasers are commercially available. With the development of high
power lasers, laser materials processing is now being used as part of the production route for
many items such that the laser is finding increasing commercial use as a cutting tool.

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2. LASER CUTTING PROCESS

2.1 WORKING PRINCIPLE.

Madic et. al. stated that laser cutting is a thermal, various manufacturing industries to produce
components in large numbers with high dimensional accuracy and surface finish. They also
stated that high power density beam when focused in a spot melts and evaporates material in
a fraction of second and the evaporated molten material is removed by a coaxial jet of assist
gas from the affected zone as shown in Figure 3

Figure 3 schematic diagram of laser beam cutting.

2.2 PROCESS PARAMETERS.

Laser cutting process has always been a major research area for getting the exceptionally
good quality of cut like reduced surface roughness, kerf width and heat affected zone (HAZ).
The following points are especially important for achieving good cutting results:

 Surface roughness
 Kerf width
 Laser power

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 Pulse frequency
 Type and pressure of cutting gas
 Nozzle alignment
 Distance between the cutting nozzle and the work piece
 Cutting speed
 Acceleration
 Work piece surface
 Material thickness
 Work piece support
 Focal position relative to the material surface

2.2.1 SURFACE ROUGHNESS.

Surface roughness is an effective and commonly adopted parameter representing quality of a
machined surface in general engineering practice. It gives a good general description of the
height variations in the surface.

The surface roughness decreases and remains same as the power increases as shown in Figure
4. Roughness increases and then decreases as the assist gas pressure increases as shown in
Figure 5.

Figure 4 surface roughness vs power.

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Figure 5 surface roughness vs assist gas pressure.

2.2.2 KERF WIDTH.

The laser melts away a portion of material when it cuts through; this is known as kerf which is
a groove or a slit or a notch. The width of the portion after the cut is called the kerf width. The
kerf width refers to the width of the slot that is formed during through thickness cutting and is
normally narrower at the bottom surface of the workpiece than at the top surface. The kerf
width represents the amount of material removed during the cutting process, which is
essentially wasted material; therefore, a smaller kerf width is.The width of the cut kerf
corresponds to the circular beam waist size which is determined mainly by the laser beam
quality and focusing optics.

Figure 6 kerf width vs power. Figure 7 kerf width vs cutting speed.

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Figure 8 kerf width vs assist gas pressure.

The power at the focused spot, cutting speed and the assist gas jet also has influence on the
size of the cut kerf. Figure shows the variation of kerf width with cutting speed, assist gas
pressure and laser output power. Increases in laser power, assist gas pressure and reduction in
cutting speed were found to result in increased kerf width.

2.2.3 LASER POWER.

The laser power must be adjusted to suit the type and thickness of the work-piece. A reduction
in the laser power may be necessary to achieve high accuracy on complex shaped work-pieces
or very small parts. In contrast a laser power of at least 1000 W is needed for cutting carbon
steel thicker than 5/16”.

2.2.4 PULSE FREQUENCY

As with the laser power, the pulse frequency can be matched to the relevant machining task.
For example, it is recommended small contours are cut with reduced pulse frequency. The
pulse frequency is also reduced when piercing in the ramp mode.

2.2.5 TYPE OF GAS.

The type of material and the requirements of the cutting results determine the cutting gas to be
used. A combustible material such as wood must not, for example, be cut with oxygen, as the

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work-piece would catch fire. Oxygen should only be used for metallic work-pieces with
oxide-free edges. Oxygen forms a thin oxide layer during exothermic combustion. With the
laser torch cutting of metallic materials the quality of the applied oxygen is particularly
important for the cutting results. Traces of water or nitrogen lead to the formation of burrs.
This type of cutting gas contamination may be caused by bottle replacement and the
connection of contaminated bottles. Therefore we recommend that the gas is supplied from
gas tanks

Recommended oxygen purity: 99.95 % (3.5). With the use of oxygen with a purity of 99.5%
(2.5) the possible cutting speed is reduced by approximately 10%.The quality of the cutting
gas (N2) is also very important for the high pressure cutting of stainless steel. Even slight
traces of oxygen lead to the formation of a fine oxide layer.

2.2.6 PRESSURE OF GAS.

The material thickness of the work-piece must be matched to the gas pressure. When torch
cutting, thin metallic materials are cut with a higher gas pressure than thicker materials. The
gas pressure must be set very carefully, because the cutting quality is affected by even slight
changes in the oxygen pressure. If the pressure is too low, the fluid slag remains adhered to
the base material, forming a permanent burr or closing the kerf again. The gas pressure must
be set very carefully, because the cutting quality is affected by even slight changes in the
oxygen pressure. If the pressure is too low, the fluid slag remains adhered to the base material,
forming a permanent burr or closing the kerf again. If the pressure is too high, the lower edges
of the cut are burnt out and often make the cut unusable. In contrast, with high pressure
cutting thicker work-pieces are cut at higher gas pressure.

2.2.7 NOZZLE ALIGNMENT.

Nozzle misalignment may cause poor cutting quality, as the process is extremely susceptible
to any discrepancy in the alignment of the cutting gas jet with the laser beam. The gas flow
from the nozzle generates a pressure gradient on the material surface, which is coaxial with
the nozzle itself. If the nozzle and the focused laser beam are coaxial, the cutting zone
established by the beam will lie directly under the central core of the gas jet and there will be
uniform lateral gas flow. Illustrates the equilibrium set up if the gas jet and laser beam are
coaxial. However, nozzle- laser beam misalignment leads to an overall directional gas

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flow across the top of the cut zone which can lead to unwanted cut edge burning and dross adhes

Figure 9 nozzle alignment.

2.2.8 NOZZLE DISTANCE.

The nozzle distance is held at the programmed value with a capacitive height control without
touching the work-piece. The nozzle distance between the work-piece and the material surface
has a great effect on the cutting quality with laser cutting. The smaller the nozzle distance, the
better the cutting quality. But there is the following restriction: To ensure safe cutting, a
minimum distance should not be maintained. This minimum distance is approx. 0.025”. For
hole piercing the nozzle distance is selected to be the same or larger depending on the
material thickness and type of hole-piercing. The smaller the distance, the more air pressure is
applied to the cutting gap. So in general, more cutting emissions are blown out of the gap, so
that there is less build-up of smoke. If you increase the distance, the air pressure applied to the
cutting gap decreases. If you increase the distance when cutting acrylic, you create smooth cut
edges, but not all flammable gases might be blown into the exhaust channels anymore. So the
point needs to be determined at which the optimum ratio between the formation of flames
(due to the flammable gases) and smooth cut edges is achieved.

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Figure 10 Nozzle diameter and stand off distance.

2.2.9 CUTTING SPEED.

The energy balance for the laser cutting process is such that the energy supplied to the cutting
zone is divided into two parts namely; energy used in generating a cut and the energy losses
from the cut zone. It is shown that the energy used in cutting is independent of the time taken
to carry out the cut but the energy losses from the cut zone are proportion to the time taken.
Therefore, the energy lost from the cut zone decreases with increasing cutting speed resulting
into an increase in the efficiency of the cutting process. A reduction in cutting speed when
cutting thicker materials leads to an increase in the wasted energy and the process becomes
less efficient. The levels of conductive loss, which is the most substantial thermal loss from
the cut zone for most metals, rise rapidly with increasing material thickness coupled with the
reduction in cutting speed. The cutting speed must be balanced with the gas flow rate and the
power. As cutting speed increases, striations on the cut edge become more prominent, dross is
more likely to remain on the underside and penetration is lost. When oxygen is applied in
mild steel cutting, too low cutting speed results in excessive burning of the cut edge, which
degrades the edge quality and increases the width of the heat affected zone (HAZ). In general,
the cutting speed for a material is inversely proportional to its thickness. The speed must be
reduced when cutting sharp corners with a corresponding reduction in beam power to avoid
burning. The cutting speed must be matched to the type and thickness of the work-piece. A
speed which is too fast or too slow leads to increased roughness, burr formation and to large
drag lines.

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Figure 11 cutting speed v/s material thickness.

2.2.10 ACCELERATION.

The acceleration is linked to the machine constants and generally it does not need any
attention since it is a setting specific to the machine. With high pressure cutting the
acceleration should be limited from about 1/8” sheet thickness, because the cutting process
can easily be interrupted if the acceleration is too high.

2.2.11 MATERIAL THICKNESS.

With high pressure cutting interruption of the cutting process may occur when cutting over
the work-piece support bars. When crossing the bars small grooves may be produced on the
lower edge of the sheet. Splashes produced by cutting into the work-piece support may adhere
to the bottom of the work-piece.

2.2.12 WORK PIECE SURFACE.

Shiny material surfaces, such as for example pure aluminum, produce strong reflection of the
laser beam and therefore also poor cutting results. With laser cutting, rolling marks and
impairs the cutting result. A loose mill scale of varying thickness does not permit the focused
laser beam to impinge directly on the surface. The cutting gas enveloping the laser beam
grooves, stamps and mechanical damage to cavities deflect laser beams and gas flows in

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undefined directions This is more noticeable with thick sheets and causes unclean cut edges
and it reduces cutting speed and performance.Spray finishes and paint and plastic coatings
affect the cutting result. Mill scaleon the on the surface of the sheet is also deflectedPlastic
coated stainless steel can be cut without burrs in thicknesses up to 1/8” using high pressure
cutting. Residues of sand grains in sand-blasted surfaces reflect the laser beam and the
roughened (pyramid-shaped) surface structure deflects the cutting gas flow on the surface. In
addition sand contains silicon which also causes problems with laser beam cutting. The rough
texture of surfaces treated by abrasive grain techniques (cup-shaped) can also deflect the
cutting gas flow on the surface. Small solidified balls of pierce slag also tend to stick to a
blasted surface, which can cause cutting defects when the laser beam cuts over them or, if
they are large enough, when the nozzle contacts them causing a crash. In contrast, a thin layer
of oil as often present on sheet material does not impair the cutting result. The oil layer has a
positive effect during piercing with 100 % laser power, since the slag accumulation on the
sheet surface is significantly reduced

2.2.13 FOCAL POSITION RELATIVE TO THE MATERIAL

SURFACE

The focal position has to be controlled in order to ensure optimum cutting performance.
Differences in material thickness may also require focus alterations and variations in laser
beam shape. When cutting with oxygen, the maximum cutting speed is achieved when the
focal plane of the beam is positioned at the plate surface for thin sheets or about one third of
the plate thickness below the surface for thick plates. However, the optimum position is closer
to the lower surface of the plate when using an inert gas because a ider kerf is produced that
allows a larger part of the gas flow to penetrate the kerf and eject molten material. Just as the
intensity of the sun affects the ability of the magnifying glass to focus and create an effective
spot size, so does the raw laser beam influence how well you can focus its energy and the size
of the focused spot that results. Here's the general rule: The larger the raw beam diameter, the
larger the resulting focal waist diameter, and the farther the focal point is projected from the
lens. Larger nozzle diameters are used in inert gas cutting. If the focal plane is positioned too
high relative to the workpiece surface or too far below the surface, the kerf width and recast
layer thickness increase to a point at which the power density falls below that required for
cutting. Optical systems with 5" and 7.5" focal lengths are typically used for cutting. 5" optics

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are only suitable for thin materials. For thicker materials the 7.5" optics are used. With the 5"
optics the kerf is narrower compared to the 7.5" optics, giving a higher energy density for the
same laser power. The possible cutting speeds for the 5" optics are therefore slightly higher
for the same material thickness and laser power.

Figure 12 Focal lengths. Figure 13 Focus points.

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3. TYPES OF LASER CUTTING.

Laser cutting has been around since the 60’s but now it’s as relevant as it has ever been due
its growing usage within industrial processes. This non-contact process uses a constant beam
of light to create heat and pressure which then reshapes/distorts various materials with
precision as the cutting head moves over the material surface. There are 3 types of lasers:

 CO2 (gas lasers)

 Fiber lasers
 Nd:YAG or Nd:YVO (vanadate crystal lasers).

3.1 CO2 LASER CUTTING.

A CO2 laser runs electricity through a gas mixture-filled tube, producing light beams. The
tubes contain mirrors on each end. One of the mirrors is fully reflective and the other is
partial, letting some of the light through. The gas mixture is usually carbon dioxide, nitrogen,
hydrogen and helium. CO2 lasers produce invisible light, in the far infrared range of the light
spectrum. The highest power CO2 lasers range up to multiple Kilowatts for industrial
machines, but these are by far the exception. Typical machining CO2 lasers are 25 to 100
Watts in power with a wavelength of 10.6 micrometers.

Figure 14 schematic diagram of co2 laser cutting.

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This type of laser is most common for working with wood or paper (and their derivatives),
Polymethylmethacrylate and other acrylic plastics. It is also useful for working with leather,
fabric, wallpaper and similar products. It has also been applied to the processing of food such
as cheese, chestnuts and various plants. CO2 lasers are generally best for non-metallic
materials, although there are certain metals that they can process. It can generally cut thin
sheets aluminum and other non-ferrous metals. One can enhance the power of the CO2 beam
by boosting the oxygen content, however this can be risky in inexperienced hands or with a
machine unsuitable for such enhancements.

3.2 FIBER LASERS.

This class of machines is part of the solid-state laser group and uses the seed laser. They
amplify the beam using specially designed glass fibers that derive energy from pump diodes.
Their general wavelength is 1.064 micrometers, producing an extremely small focal diameter.
They are also typically the most expensive of the various laser-cutting devices.

Fiber lasers are generally maintenance-free and feature a long service life of at least 25,000
laser hours. Thus, fiber lasers have a far longer lifecycle than the other two types and they can
produce strong and stable beams. They can manage intensities 100 times higher than that of
CO2 lasers with the same amount of average power. Fiber lasers can be in continuous beam,
quasi- or offer pulsed settings giving them different functionalities. One sub-type of fiber
laser system is the MOPA, where pulse durations are adjustable. This makes the MOPA laser
one of the most flexible lasers, which can be used for multiple applications Fiber lasers are
optimally suited for metal marking by way of annealing, metal engraving and marking
thermoplastics. It works with metals, alloys and non-metals alike, even including glass, wood
and plastic. Fiber lasers, depending on the power, can be quite versatile and deal with a ton of
different materials. While working with thin materials, fiber lasers are the ideal solution.
However, this is less so the case for materials over 20 mm although, a more expensive fiber
laser machine that can work with over 6 kW could do the trick.

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Figure 15 Fiber module.

3.3 Nd:YAG/Nd:YVO LASERS.

Crystal laser cutting processes can be in nd:YAG (neodymium-doped yttrium aluminium

garnet), but more commonly they tend to use nd:YVO (neodymium-doped yttrium ortho-
vanadate, YVO4) crystals. These devices allow an extremely high cutting power. The
drawback of these machines is that they can be expensive, not just because of their initial
price but also because they have a life expectancy 8,000 to 15,000 hours (with Nd:YVO4
being having a typically lower one) and the pump diodes can net a very hefty price. These
lasers offer a wavelength of 1.064 micrometres and are useful for a huge range of
applications, from medical and dentistry to military and manufacturing. When comparing the
two Nd:YVO exhibits higher pump absorption and gain, a broader bandwidth, broader
wavelength range for pumping, a shorter upper‐state lifetime, a higher refractive index and
lower thermal conductivity. When it comes to continuous operation, Nd:YVO has an

overall similar performance level to Nd:YAG in cases with medium or high power. However,
Nd:YVO does not allow for pulse energies as high as Nd:YAG and the laser life lasts for
shorter periods. These can be used with both metals (coated and non-coated) and non-metals,
including plastics. Under certain circumstances, it can even process a few ceramics. The
Nd:YVO4 crystal has been incorporated with high NLO coefficient crystals (LBO, BBO, or

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KTP) to frequency-shift the output from the near infrared to green, blue, or even UV which
gives it a ton of varying functions. Due to the similar sizes, yttrium, gadolinium or lutetium
ions can be replaced with laser-active rare earth ions without strongly affecting the lattice
structure needed to produce the beam. This preserves the high thermal conductivity of the
doped materials

Figure 16 (a) Schematic of the Nd:YAG laser setup.

(b) Structure of the Nd:YAG/Cr:YAG crystal.
(c) Schematic of the Nd:YVO 4 laser.

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4. APPLICATIONS OF LASER CUTTING.

Laser cutting is now one of the most widely used manufacturing processes in the world.
Finding a home in industries such as the aerospace, automotive, electronics, semiconductor
and medical sectors, it’s clear that it offers a huge range of benefits and uses. The cutting
process works in a vastly different way compared to how it has previously been done in the
past, offering a new level of quality and reliability to its users. To help demonstrate just how
varied this process can be we have listed below some of the applications for this type of laser
process.

4.1 THE LASER CUTTING OF METALS.

One of the most common applications is to cut metal. This process can be used on a huge
number of different metals, including steel, tungsten, nickel, brass and aluminium. Regardless
of the industry or the work that is conducted in that industry, it’s more than likely that metal
will play a part in some way. Whatever the thickness of the metals, a laser can be used to
deliver the same clean cuts and smooth finishes. You’ll commonly see a laser cut metal for
components and structural shapes, such as for the body of a car or the casing of a mobile
phone.

Cutting with lasers is often used for the cutting of metal hydro formed parts. These are strong
tubes that are commonly used to provide support, such as for engine frames or instrument
panel beams.

4.2 CUTTING OF REFLECTIVE METALS.

As well as using laser cutting to cut traditional metals such as steel, this process can be used
on reflective metals too.Furthermore, we can use the process to create complex and intricate
shapes.

4.3 USE IN LASER SURGERY.

As well as metals, wood and food, the process is also useful for working with humantissue
too. Laser cutting is already used in the medical sector to create many of the medical
devicesthat we use every day, such as life-saving stents and test tubes. Laser surgery simply
provides another reason why the medical sector couldn’t do without this new cutting

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technology. A laser beam is is used instead of a scalpel, and is conducted by vaporising the
human tissue. The most common form of laser surgery is laser eye surgery

4.4 CUTTING OF SILICON.

One of the biggest uses for is for working with silicon. Silicon is an extremely important
material, used in multiple industries including solar, microelectronics and semiconductors.

As this helps to operate most of the technological products that we use every day, the
importance of lasers in silicon cutting can’t be understated. As the process offers more
precise cuts than were previously achievable by past machines, the silicon products and
components have been able to adapt to become smaller and smaller. This allows for the
continuous number of innovations and developments that we’ve seen in the world of
technology.

4.5 CUTTING OF CERAMICS.

Laser cutting is also commonly used to cut ceramics too. Ceramics play an important role in
many industries thanks to its thermal conductivity and electrical insulation, so it is used in a
number of different applications

4.6 LASER MARKING AND LASER ENGRAVING.

Two of the most common applications that lasers can also perform are laser
marking and laser engraving. Engraving or marking can be added to an object to increase its
aesthetic value, complete a product or to have a more practical function, such as adding a
barcode. There are thousands of items that have been laser marked or laser engraved. These
processes are also extremely common in the jewellery industry, used to mark or engrave all
varieties of jewellery.

4.7 CUTTING OF OTHER NON METALS

As you’ve probably gathered by now, laser cutting can be used on a huge number of
differentmaterials. Some of these are non-metal materials like polymers, carbon composites,
plastics and rubber..

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CONCLUSION.

The work presented here is an overview of research work carried out in laser cutting
process. From the above discussions it can be concluded that :

 Laser cutting process is capable of cutting complex profiles in most of the materials with a
high degree of precision and accuracy.
 The performance of laser cutting process depends on the input process parameters like
laser power, cutting speed, assist gas pressure etc and also on the important performance
characteristics like surface roughness, HAZ and kerf width.
 This paper just presents an overview of the recent experimental investigations in laser
cutting of various engineering materials concerned with cut quality like surface roughness,
HAZ and kerf width and identifies the most common process parameters and cut quality
characteristics.

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REFERENCES

 M. Madic, M. Radovanovic and B. Nedic, “Correlation between Surface Roughness

Characteristics in CO2 Laser Cutting of Mild Steel”, Tribology in Industry, Vol. 34, 2012,
232-238.
 Naimesh R Kadiya, PROF. JIGNESH PATEL, “Literature Survey on Laser Cutting Machine
Process Parameter”, International Journal of Research in Modern Engineering and Emerging
Technology. Vol. 1, Issue: 2, March-2013. [4] Ph.D. Snežana Radonjić, M.Sc. Anđelija
Mitrović, Ph.D. Pavel Kovač, “Defining new processing parameters g and Emerging
Technology. Vol. 1, Issue: 2, March-2013.
 Ph.D. Snežana Radonjić, M.Sc. Anđelija Mitrović, Ph.D. Pavel Kovač, “Defining new
processing parameters in laser cutting”. 16th International Research/Expert Conference. 10-
12 September 2012.
 V.Senthilkumar1, N.Periyasamy2, A.Manigandan3, Parametric Investigation of Process
Parameters for Laser Cutting Process” International Journal of Innovative Research in
Science, Engineering and Technology, Vol. 4, Issue 5, May 2015.
 Yilbas B. S., “Effect of process parameters on the kerf width during the laser cutting process”,
Proceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering
Manufacture, Volume 215, Number 10, 2001, ISSN: 0954-4054, pp. 1357 – 1365

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