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Research
Themes in Laser Material Processing
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being carried out by the Laser Group at the University
of Liverpool
and the Lairdside Laser Engineering Centre
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| Laser Forming |
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Laser
forming is a non-contact technique for the shaping of
metallic sheet components.
It can be used for
rapid
prototyping of complex 3D shapes
adjusting
and aligning
remotely of components
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The
mechanism of 2-D bending has been modelled using finite
element analysis.
Current work is considering the laser scan parameters
modeling and process control required for the formation
of more complex 3-D shapes.
An example of application is in the use of laser bending
to create on-board microactuators for the alignment of
microelectronic components. |
| EPSRC
GR/NL Contract Partners: University of Liverpool, Heriot
- Watt University, University of Cambridge, Rolls - Royce,
BAE Systems |
Papers
on Laser Forming 
- 3D
laser forming of saddle shapes
S.P.Edwardson,K.G.Watkins,G.Dearden,J.Magee
- Laser
Forming of Aerospace Alloys
K. G. Watkins, S. P. Edwardson, J. Magee, G. Dearden,
P. French, R. L. Cooke, J. Sidhu, N. J. Calder
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| Laser
Cladding and Direct Fabrication |
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Laser
Direct Fabrication is the building of claddings or objects
directly from powders using a laser for melting of the
powders
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Computer
control of composition during laser cladding allows
the whole composition range of alloy systems to be
generated
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Layer
by layer deposition allows components to be deposited
directly from CAD designs
Compositionally graded structures for optimised design
and performance
Turbine blade
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Hardness
Map
  Hip
joint
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Removal
of radioactively contaminated surface layers of concrete
by novel laser method
Allows
action at a distance so that expensive equipment is
not itself contaminated during use
Can
be applied with both high power CO2 and Nd:YAG lasers
Material
removed by laser scabbling can be removed as high/medium
level waste while the remaining structure can be classified
as low level waste, hence minimising decommissioning
costs
Being
further investigated by BNFL as a possible means of
decommissioning of nucelar installations
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Concrete
as received
Concrete
after one pass laser scabbling |
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Papers
on Laser Scabbling
- Particle
size analysis of material removed during CO2 laser
scabbling of concrete for filtration design Lobo LM,
Williams K, Johnson EP, Spencer JT
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Laser
percussion drilling is being developed to reduce hole
formation time while maintaining hole quality
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Turbine
blades operate at high temperature as a result
of a flow of air which produces boundary layer
cooling Blades are hollow and require accurately
machined holes to duct the required air flow
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Mechanism
of laser percussion drilling 
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Papers
on Laser Drilling
- Investigation
of the Nd:YAG laser percussion drilling process using
high speed filming
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Mechanisms
of laser cleaning  |
Removal
of surface particles or layers by pulsed laser radiation
Uses
in art restoration, cleaning of microelectronic components,
industrial cleaning
Not
just one process, many mechanisms involved depending
on laser fluence and pulse length
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Two new mechanisms
for laser cleaning
Angular
laser cleaning
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Laser
shock cleaning
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Papers
on Cleaning
- Two
new mechanisms for laser cleaning using Nd:YAG sources
- Ultraviolet
laser removal of small metallic particles from silicon
wafers
- Effect
of wavelength and incident angle in the laser removal
of particles from silicon wafers
- Chromatic
modulation technique for in-line surface monitoring
and diagnostic
- A
study of the effect of the wavelength in the Q-switched
Nd:YAG laser cleaning of gilded wood
- Dust
Removal from Next Generation Tokamaks by Laser and
Flashlamp Cleaning
- More
papers on Laser Cleaning can be found here
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| Laser
Welding |
Laser
Conduction Welding of Aluminium Alloys for increased pentration
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Semi-quantitative
analysis of the LCW process
maximum
penetration depth is produced as a result of the competition
between the two processes; heat energy loss by boiling
and heat transfer by conduction
At
the critical spot size, when maximum penetration occurs,
there is just sufficient input to maintain the surface
at the boiling point. At larger sizes there is insufficient
absorbed energy intensity to maintain the surface
temperature at boiling. At smaller sizes excess energy
causes increased boiling
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Example
of Laser Conduction Butt Weld
made
in 3mm thick Aluminium Alloy
using
YAG Laser
LC
Welds show higher fracture strength than Laser Keyhole
Welds in this material
Slower
rates of cooling may enhance weld properties in traditionally
difficult materials
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Blast
and Impact Resistance Studies of Laser Welded Panel
Structures combining the expertise of the Laser and
Impact Research Groups at the University of Liverpool
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Blast
testing of panel structures
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FE
analysis of laser welded panel
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Papers
on Welding
- Laser
Welding of Aluminium Alloy 5083
- Blast
and impact resistance studies of laser welded and
riveted panel structures
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| Laser
Ignition in IC Engines (LASIIC) |
- Laser
ignition of air-fuel mixtures in the laboratory has
shown that improved ignition and kernal growth in
lean mixture may be possible, leading to an increase
in the lean burn limit by 1 to 3 air-fuel ratios (AFR's)
compared to conventional electric spark ignition
- Faster
burn rate is possible with higher thermal effiency
- Reduction
in peak cylinder pressure fluctuations may allow more
stable combustion, more demanding lean burn strategies,
lower idle speeds and better cold engine performance
when compared to conventional spark plug ignition
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- LASIIC
is investigating techniques for evaluating the practical
feasibility of these potential advantages with realistic
engineering constraints by applying laser ignition
in the latest generation of vehicle test engines
- The
project is funded by the DTI / EPSRC Foresight Vehicle
LINK initiative and involves a consortium comprising
the University's Laser Group and IC Engines Group,
Ford Motor Company and Spectron Laser Systems
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