International Journal of Engineering Trends and Technology (IJETT) – Volume 6 Number 5- Dec 2013
Material Processing by Laser: A Review
Vijay Narayana* Nitesh Guptab S.M Farhanb
a:Department of Physics S.R.M.G.P.C.Lucknow
b:Department of Mechanical S.R.M.G.P.C.Lucknow
Abstract:-This work investigates the application of the CO2
laser & Nd-YAG cutting processes examined were in
different thicknesses ranging from 2 to 10 mm. The process
parameters were examined as:o
Laser power
o
Range of cutting
o
Speed
o
Type of focusing lens
o
Pressure and flow of the covering gas
o
Thickness of the samples
high power laser emphasised with the help of computer,
at the materials to be cut by laser. The material then
burns, melts or is blown away by a jet of gas impact,
leaving an edge with a high-quality good surface finish.
Laser cuttings are mainly concerned with industrial
application such as cutting, drilling & boring of any solid
state article. [3]
II.
TYPES OF LASER CUTTING:
Index terms:-Types of laser cutting, process of cutting,
finishing and tolerance.
I.
INTRODUCTION
After the discovery of first solid state laser ( ruby laser)
“used for drilling & boring for diamond dies in
engineering research centres. In 1967, the British
pioneered laser-assisted oxygen jet cutting for materials
& metals. In the early age of 19tees, this technology was
put into production to cut Titanium for aerospace
applications. At the same time CO2 lasers were borrowly
used to cut non-metallic’s, such as ceramics, tiles,
because it were absorbed by metals.
CO2 lasers are used for industrial cutting of many
materials including MS, Al, SS, Titanium, wax, plastics,
wood, ceramics and fabrics. YAG lasers are primarily
used for cutting and scribing metals and ceramics.
As we know that the power of any kind of lasing source
will shows the greater dependency of lasing cavity in
which mixture of CO2, He2 & N2 are incorporated with
high speed in corresponding lasing cavity via compatible
resources.
The above mention process requires no pressurization,
while for cooling of any lasing devices water circulating
systems are used as per cavity size. [2] Laser cutting is a
technology that uses a laser to cut materials, and is
widely used for industrial tranforming finished product &
applications, but is also starting to be used by small
businesses and small industries. It will directly used as a
ISSN: 2231-5381
A diffusion cooled resonator
There are various types of lasers used in material
processing. The Carbon dioxide laser is well suited for
cutting, drilling, boring and engraving. The Neodymium
(Nd) and Neodymium Yettrium-Aluminium-Garnet (NdYAG) lasers are identical in style and differ only in
application. The Nd-YAG laser is used where very high
power is needed and for boring and engraving. Both CO2
and Nd-YAG lasers can be used for welding Common
variants of CO2 lasers include fast as well as slow axial
flow.
CO2 lasers are commonly "pumped" by passing a current
through the gas mix (DC-excited) or using radio
frequency (RF) energy. The Radio Frequency procedure
is new and popularly used in laser cutting. CO2 lasers are
used for industrial cutting of many materials including
MS, Al, SS, titanium, paper, wax, plastics, wood,
ceramics and fabrics. YAG lasers are primarily used for
cutting and scribing metals and ceramics.
The active medium used in such devices; electrical
pumping are required for its proper lasing. In a fast axial
flow resonator, the mixture of carbon dioxide (CO2),
http://www.ijettjournal.org
Page 257
International Journal of Engineering Trends and Technology (IJETT) – Volume 6 Number 5- Dec 2013
helium (He) and nitrogen (N2) is circulated at high
velocity by a turbine or blower.
The Any lasing system needs cooling devices across it
while performing lasing action due to which its
sustainability elongated for larger times. In the same kind
of requirements water coolant circulated throughout the
lasing devices directly for heat transfer depending on
size.[4]
There are two types of cutting:
1. VAPORIZATION CUTTING:-The quality of the
resulting cut is excellent in vaporization cutting. It will be
certainly remembered that to providing proper finishing a
compressed air pressure may be low or for rough
finishing it will be adequately high. [5,6]
Fig.2. Cutting speed vs. laser power level for 5mm thick
sheets of PE, PP and PC. [11]
III.
2. FUSION CUTTING:-The majority of thermoplastic
polymers are cut by fusion of the material. The
mechanism underlying this phenomenon is similar to that
of metal cutting with inert gases, since the laser beam
produces fusion while the covering gas removes the
molten material, thus creating the actual phenomenal
severing of the piece. In the case of polymers, the gas
used is compressed air. Kerfs widths range from 0.2 to
0.8 mm, and vary according to the thickness of the
material. The cut edge and faces are macroscopically
smooth with some streaks, which are produced by the
melted material, that run from the laser-beam entry point
to its exit point materials that are cut by fusion include
PE, PP and PC. [7-10]
PROCESS
Fig. 3: laser gas cutting
Industrial Laser Cutting of Steel with Cutting Instructions
Programmed through the CNC Interface, Generation of
the laser beam involves stimulating a lasing material by
electrical discharges or lamps within a closed chamber.
When the lasing material is stimulated, then the beam is
reflected with the help of partial mirror internally, until it
collectively absorb sufficient energy to escape as a
stream of monochromatic coherent light. Mirrors or fibre
optics are commonly used to focuse the coherent light
towards a lens, which focuses the light at the job-work
zone. The narrowest part of the focused beam is generally
less than 0.0125 inch (0.3175 mm) in diameter.
Depending upon material thickness, kerfs widths as small
as 0.004 inch (0.1016 mm) are possible.[12]
Fig.1. Cutting speed vs. thickness for different laser
power levels for PE sheets [11]
In order to achieve the desired cutting rather than edge of
a job-work, then a pierce slot is done before every
cutting. Piercing usually indicate a high-power pulsed
laser beam which slowly makes a slot or hole in the
material, taking around 5–15 seconds for 1⁄ 2-inch-thick
(13 mm) stainless steel.
For example: The parallel rays of coherent light from the
laser source often fall in the range between 1/16 inch to
ISSN: 2231-5381
http://www.ijettjournal.org
Page 258
International Journal of Engineering Trends and Technology (IJETT) – Volume 6 Number 5- Dec 2013
1/2 inch (1.5875 mm to 12.7 mm) in diameter. This beam
is usually focused and intensed via lens or a mirror to a
very small spot of about 0.001 inch (0.0254 mm) to
create a very high laser beam. In order to achieve the
smoothest possible finish during contour edge cutting, the
direction of laser beam polarization must be rotated
around the periphery of a work piece. For galvanised
sheet (GI) cutting, the focal length is usually between
1.49 inches approx and 3 inches (38.1 mm and
76.2 mm).[13]
IV.
CLEARANCE AND CASE FINISHING
Standard roughness (Rz) increases and decreases
respectively with the sheet thickness and with laser
power & cutting speed. At the time of cutting low carbon
steel (0.15-0.45% of carbon) with laser power of 750-800
W, standard roughness Rz is 8-10 µm for sheet thickness
of 0.5-1 mm, 15-20 µm for 1-3 mm, and 20-25 µm for36 mm. where, steel sheet thickness in mm laser power in
kW (some new laser cutters have laser power of 4 kW.)
cutting speed in meters per minute [14]
This process is capable of holding quite close tolerances,
often to within 0.001 inch (0.025 mm) Part geometry and
the mechanical soundness of the machine have much to
do with tolerance. The identical surface finish resulting
from laser beam cutting may range from 125 to 250
micro-inches (0.003 mm to 0.006 mm). [15]
TABLE I: Application of various lasing materials
Lasing Materials
Applications
CO2
Boring
Cutting/Scribing Engraving
Nd
High-energy pulses
Low repetition speed (1 kHz)
Boring
Nd-YAG
Very high energy pulses
Boring Engraving Trimming
Laser cutting for metals has the advantages over plasma
cutting of being more precise and using less energy when
cutting GI sheet metal, rather than the lasers cutting
cannot be used for greater metal thickness that plasma
can. Newer lasers cutting machines operating at higher
power (6000 watts, as contrasted with early laser cutting
machines' 1500 watt ratings) are approaching plasma
machines in their ability to cut more thick materials, but
the capital cost of such machines are much higher
compare to plasma cutting machines capable of cutting
thick materials like steel plate.
The main disadvantage or demerit of laser cutting that it
requires the high power current. Industrial laser
efficiency may range from 5% to 15%. The power
consumption and efficiency of any particular laser will
vary depending on output power and operating
parameters. The amount of power required for laser
cutting, known as heat input, for a particular job-work
depends on the material type, thickness, process used,
and cutting rate.
TABLE II: Heat required for co2 laser (in watts) [16].
Material
Material thickness (in)
0.02
0.04
0.08
0.125
0.25
Stainless steel
1000
1000
1000
500
250
Aluminium
1000
1000
1000
3800
10000
Mild steel
-
400
-
500
-
Titanium
250
210
210
-
-
Plywood
-
-
-
-
650
Boron/epoxy
-
-
-
3000
-
TABLE III: Cutting rates for various materials and
thicknesses using aCO2 laser [ipm]
Work piece
Material
V.
Material thickness
0.02
0.04
0.08
0.125
0.25
.50
in.
0.508
1.016
2.032
3.175
6.35
12.7
mm
Stainless steel
1000
550
325
185
80
18
Aluminium
800
350
150
100
40
30
Mild steel
-
210
185
150
100
50
Titanium
300
300
100
80
60
40
Plywood
-
-
-
60
60
25
Boron/epoxy
-
-
-
-
180
45
ADVANTAGES AND DISADVANTAGES
Advantages of laser cutting over mechanical cutting
include easier work holding and reduced contamination
of work piece since there is no Precision, since the laser
beam does not wear during the process. Due to a small
heat-affected zone (HAZ) in laser cutting it will be
highly recognised to develope less chance of warping
defect in the metal job-work piece.. It is also very
difficult or impossible to cut some materials by more
traditional means.
ISSN: 2231-5381
http://www.ijettjournal.org
Page 259
International Journal of Engineering Trends and Technology (IJETT) – Volume 6 Number 5- Dec 2013
VI.
CONCLUSION:
 This process is widely applicable for different Laser Cutting
in the current manufacturing market.
 More new discoveries and innovations are on the process as
for this versatile laser cutting process and cropping time to
time each year.
 The laser cutting application is most useful for growth of
developing & developed countries both.
REFERENCES
[1]^Bromberg 1991, p. 202.
[2]^Bromberg 1991, p. 204.
[3]^Oberg, p. 1447
[4] ^ ab Todd, p. 186.
[5] P.A.Atanassov, CW CO2 laser cutting of plastics,
SPIE, Vol. 3092 Edinburgh, 1997, pp. 772–775.
[6] S.I. Powel, CO2 Laser Cutting, LASER 5: Laser
Materials Processing for Industry, IITT International
Gournay Sur Marne, 1989, pp. 54–71.
[7] X. Schmidt, C.A. Marlies, Principles of High-polymer
Theory Anti Practice, McGraw-Hill, New York, 1948.
[8] J. Bandrup, E. Immergut, Polymer Handbook, 3rd ed.,
Wiley/ Interscience, New York, 1989.
[9] L.E. Nielson, E. Lawrence Nielsen, Mechanical
Properties of Polymers, Marcel Dekker, New York, 1974.
[10] D.M. Van Krevelen, Properties of Polymers,
Elsevier, Amsterdam, 1990.
[11]. Caiazzo et al. / Journal of Materials Processing
Technology 159 (2005) 279–285
[12]^Todd, p. 185.
[13]^Todd, p. 188
[14]^Research on surface roughness by laser cut by
MiroslavRadovanovic and PredragDašić
[15]^ abTodd, p. 186
[16]^Todd, Allen & Alting 1994, p. 188.
ISSN: 2231-5381
http://www.ijettjournal.org
Page 260