This document summarizes laser machining of structural ceramics. It discusses that structural ceramics are hard and brittle materials that are difficult to machine using conventional methods. Laser machining provides a potential solution as a non-contact thermal process. The document describes different types of lasers used for machining ceramics, including CO2, Nd:YAG, and excimer lasers. It also discusses one, two, and three-dimensional laser machining processes and examples of laser machining of silicon carbide ceramics. In conclusion, laser machining of structural ceramics is an emerging field with applications in microfabrication and potential for further research.

1. VISVESVARAYA NATIONAL INSTITUTE OF TECHNOLOGY
NAGPUR-440010
LASER MACHINING OF STRUCTURAL CERAMICS
Presented by
PRAYAG A. BURAD
MT18MTE012

2. CONTENT
• Introduction
• Structural Ceramics
• Laser machining
• Type of laser used
• Type of machining process
• Structural ceramics machining by laser
• Laser micromachining
• Conclusion
• References

3. INTRODUCTION
• Structural material is defined as any material whose primary purpose is to
support a force. (load bearing)
• Structural material can be metallic, ceramic, polymeric or a composite
between these materials.
• A ceramic is a solid material comprising of inorganic compound of metal,
non-metals and metalloids atoms primarily held in ionic and covalent bond.
• Mechanical and physical properties of ceramics as compare to metals and
polymer are excellent.
• For such hard and brittle material, using conventional machining is difficult
and affects the efficiency of that component.
• For such components, laser machining is introduce as a potential technique
solution for attaining high material removal rate

4. Classification : Structural material
Metal Polymer Ceramics
Strong & Tough Light & Cheap • Hard & Brittle
• Superior wear
resistance
• Lower thermal
conductivity
• Anticorrosive
• Retention of these
properties at high
temperature
• Exclusive solution to
several engineering
problems
• Heavy
• Corrosive
• Limitation on max
operating
temperature
• Easy to fabricate
• Used at temperature
below 300 deg. Only
• Environmentally
hazardous
Still hindered from several applications because
of its limitation towards machining into desired
components.
Examples-Alumina(Al2O3),ZrO,SiC,B4C

5. STRUCTURAL CERAMICS
• As the name suggested, ceramics which served as a structural member, often being
under mechanical loading, are classified under structural ceramics.
• The strong bond strength in these ceramics allow them to be employed in several
applications.
• Structural ceramics are classify as
Oxides (Alumina, Zirconia and their derivative),
Non-oxides (carbide, boride, nitride) and
Composites (combination of oxides and non-oxides).
• Commonly used structural ceramics are zirconia , boron carbide (B4C), alumina
(Al2O3), silicon carbide (SiC), silicon nitride (Si3N4), sialon (Si-Al-O-N), Berylia
(BeO), Magnesia (MgO), Titanium carbide (TiC),Titanium nitride (TiN), Titanium
diboride (TiB2), Zirconium nitride (ZrN) and zirconium groups: conductive
ceramics such as carbides, borides or nitrides and ceramics that are a mixture of
dielectric (semi conductive) materials and electrically conductive materials such as
Si3N4-TiN, sialon-TiN, and Si3N4-SiC.

6. LASER MACHINING
• The source of energy is a laser (Light Amplification by Stimulated Emission of
Radiation).
• Used light energy from a laser to remove material by vapourisation and ablation.
• Energy is concentrated optically.
• The laser beam is focused on to the workpiece and can be moved relative to it.
• Laser emits either continuous and pulsed light
• Lasers can replace mechanical material removal methods in several engineering
applications because of their following features
Non contact process,
Thermal process,
Flexible process.

7. Fig. Schematic of Laser machining Fig. Laser material interaction

8. TYPE OF LASER USED
Type of laser Description Wavelength Application
• CO2
CO2 lasers are molecular lasers
that uses gas molecules
(combination of carbon dioxide,
nitrogen and helium) as the lasing
medium.
10.6μm
CO2 lasers are widely
used for the applications
in laser machining, heat
treatment and welding.
• Nd:YAG
Solid state lasers uses dopants
(Neodinium (Nd3+)) dispersed in
a complex crystal of Yttrium-
Aluminum-Garnet (YAG) with
chemical composition (Y3Al5O12)
to generate laser light.
1.06μm
This lasers are used in
applications of hole-
piercing and deep key
hole-welding.
• Excimer
Excimer lasers are an increasingly
popular type of gas lasers made
up of a compound of two
identical species (exist only in an
excited state)
0.193 to 0.351μm
Excimer lasers are used
for micromachining
ceramics and
semiconductors.

9. TYPE OF MACHINING PROCESS
• One dimensional laser machining
Laser drilling (one-dimensional) machining by keeping the laser beam
and ceramic stationary. The material removal rate is governed by velocity of
erosion in the direction of laser beam.
• Two dimensional laser machining
Laser cutting (two dimensional), Motion of laser beam or ceramic in
only one direction leads to cut the ceramic. A cutting is formed when the laser
beam melts and vapourizes the material throughout the thickness and depth.
• Three dimensional laser machining
Motion of one or more laser beams or the workpiece in more than one
direction leads to three-dimensional machining. Laser turning and laser milling
are commonly used in this type of machining.

10. Fig. Schematic of basic laser machining process (a) laser drilling (one dimensional
machining), (b) laser cutting (two dimensional machining, (c) engraving a star by
laser beam (three dimensional machining)

11. STRUCTURAL CERAMICS MACHINING
BY LASER
• In an conventional machining techniques done in structural ceramics, there is
a limitation that mechanical and thermal damage, unacceptable tool wear,
lower material removal rate and high operating cost.
• For such ceramics, there is a potential solution of laser machining as a
innovation and potential tool for bulk material removal and shaping of
structural ceramics.
• Non contact process which eliminates tool wear.
• As the thermal conductivity of structural ceramics is generally less, so the
absorption takes place faster and 100% of incident energy is expected to be
immediately absorbed by ceramics for machining process.
• There is a need of obtaining desired surface finish at much higher material
removal rate for such ceramics, so the laser machining is an desired solution.

13. • Silicon carbide as a structural ceramic that has been widely machined by lasers for
different purposes.
• Based on the experimental study, Sciti and Bellosi used a pulsed CO2 laser with
laser powers of 0.5 and 1 kW for drilling the ceramic surface. The beam was
incident on the surface at an angle of 90 deg and three different focal lengths of
95.3, 63.5, and 31.8 mm were used for machining. . The hole-depth increased with
the pulse duration.
• A 5mm thick SiC plates with a 10kW Nd:YAG laser at a cutting speed of 40
mm/min. For SiC processed by KrF excimer lasers and the surface showed flat as
well as rough areas.
• Fig. laser machining in 2mm and
3mm SiC plate.

14. Laser Micromachining
• Producing parts with micro and meso scale features in the field of
semiconductors.
• Laser micromachining as compare to mechanical micromachining ,focused
ion-beam micromachining is a new technique and provides improved
flexibility in dimensional design of miroproducts and being used in
microfabrication.
• Laser micromachining of ceramics can also be used for producing parts at
micro and meso scale.
• Material removal in this machining mainly takes place by ablation and laser
assited chemical etching.
• Laser micromachining of structural ceramics is still a gray area and has
immense potential for research and application.

15. Application
• Micro-holes can be laser micro-drilled in ceramics, metal and other
semiconductors etc.
• Laser precision cutting is an attractive micromachining technique for most
structural ceramics such as alumina, silicon nitride and machinable ceramics
etc.
Fig. laser drilling Fig. laser cutting
( Pic. Warsach scientific , advance instrument research and industry)

16. CONCLUSION
• The market of structural ceramics has been steadily increasing.
• Better understanding of various physical phenomena associated with the
machining process and its influence on structural ceramic during laser
machining.
• Extensive research on silicon nitride has leads to new area of application
such as ceramic bearing and ceramic spring.
• Laser machining of structural ceramics is a budding field with tremendous
application in future.

17. Reference
• Anoop Samant, and Narendra Dahotre , Laser machining of structural
ceramics – A review J. Eur, ceramic society, 2009, 29, 969-993.
• Tuersley, I.P., Jawaid , A., and Pashby , I.R., Review: Various methods of
machining advanced ceramic materials .J. mater
• Kovalenko, V.S. and Laurinovich , A. V. Laser machining of ceramic
material. 6th Int. conference on production engineering 1987.pp.627-631
• Laser micromachining of glass, silicon and ceramics, Advance in material
science and engineering,(volume2015,review article) L.Rihakova and
H.Chmelickova.

18. THANK YOU