LATRE
- LAser Tool REcovery
Introduction
Laser beam cladding processes processes create a surface
of the required material properties bonded to the bulk
substrate material, the surface having different properties
from the material of the component being clad. This is
achieved by heating and melting the surface of the substrate
material with the laser beam and at the same time feeding
filler material in either powder or wire form. The melt
pool in the substrate combines with the fed material, which
also completely or partially melts in the beam, to create
an interface bonding the substrate material to the clad
surface, and a surface of clad material in which dilution
by the substrate is kept a minimum. Laser cladding has
been extended to applications such as component repair
and rapid fabrication, which may be covered by the less
specific term ‘Laser Material Deposition’.
Classic applications of the cladding process include the
hardfacing of gas turbine blades for aero-engines, steam
turbine component repair, car engine valve seat cladding,
the repair or plastic injection and forming tools, and
the rapid fabrication of tooling.
Advantages of laser material
deposition
Laser material deposition has a number of advantages
compared to other repair processes, including:
- Chemical cleanliness
- Low heat input on component being
treated, and therefore low distortion
- Low dilution
- Good fusion bonding
- Low porosity
- Small heat affected zone
- Good reproducibility
- Low post-process machining requirement
- High flexibility
(range of substrate and cladding materials, and component
and process configuration)
The main disadvantages are
the high initial investment in equipment required
and
(compared to some of
the above) a slow process rate.
Recovery
Provided that repairs are correctly
designed and carried out, laser
welding can be
used for reclaiming
damaged
components. The potential of
material deposition processes for tooling
and component repair and recovery
applications has also been identified.
By matching
the feed material
to the
component materials, damaged
features may be rebuilt to their original
geometry using a laser surface
coating treatment which falls
in the range
of processes described
above - welding,
cladding and direct casting – utilising
the same equipment. Examples of
potential applications
include repairs
of mould process tooling, press
tools, power generation equipment
components, construction equipment
components,
etc. Conventional finishing of
the component may be required after
the recovery process, although
this could be limited
to surface finishing and drilling. Tool recovery would permit life
extension of expensive tooling
which would
otherwise have
to be scrapped
and replaced at greater cost.
A greater savings potential
could be the
reduction of down time caused
by tool damage, which could be prohibitively
expensive,
especially if
the luxury
of spare tooling is not afforded.
Rapid
replacement of vital
tooling is inevitably costly:
laser tool recovery could substitute
replacement by repair, and
cut down time drastically,
as the process is fast when compared
to the replacement of tools not
bought off-the-shelf.
LATRE Project
description
The LAser Tool REcovery (LATRE)
project will be based on a Rofin
Triagon
9000 9kW CO2
laser with
4-axis CNC
control
at the Dept. of Metallurgy and
Materials of the University of
Malta. The project
is partially
funded by the University
of Malta. The project will include:
- fabrication and testing of the deposition nozzles
- determination
of laser material deposition parameters
- investigation
of recovery procedures
- laboratory and operational testing
Local plastic injection
moulding companies are being targeted initially
for the purpose of holding trials, although other
prospective users
of the system will also be considered. Trials will include
identification of
tool
and
feed materials, test runs on tool material samples
for metallurgical investigation, trials on scrapped
tooling with recovery potential, further
metallurgical investigation
of the tool repairs carried out, and finally operational trials of a
recovered tool.
Based on findings
from the preliminary
tests, overlay materials would be deposited on worn moulds
supplied by the industrial
partners. The necessary
machining/finishing would be carried out by the respective component
manufacturers who would
also be responsible
for carrying
out field tests using reclaimed moulds. Financial data would
be gathered
in order to quantify savings resulting
from
tool reclamation. The
duration of the project
is expected to be 30 months.
The LATRE system will also include a service
potential investigation
aspect, identifying and recording
potential clients
in a database and their possible tooling recovery
requirements; tool
materials, feed materials and recovery records will be included,
and eventually a recovery CNC
program archive
will be compiled.
Conclusion
The LATRE project is aimed
at developing
utilisation of a flexible
laser
material deposition
system at the University
of Malta. The
system will permit standard welding,
cladding and
direct laser
casting procedures
as well as tool
repair applications. System
development will increase the potential
of the laser
equipment, will
provide an opportunity
for staff, students
and partners
working on the
project to research and
implement the
solutions
required,
and will
enhance communication
and networking between the
partners involved
and with other
Maltese industries.
Once completed
and in operation,
the system will be a focus point for
the participants
in the
project,
permitting further
research into welding, cladding
and direct laser
casting, in areas
including materials research,
production engineering
and control engineering.
It will
also support
research in other
areas by providing
useful joining, surface treatment,
and low-volume
production services.
Use of the equipment will
also be extended
to support local industry in their
requirements. |
