AFRICAN FUSION—MARCH2014
17
Sustainability through automation
Figure 4: Balance+30%; wire feeding 8,0m/min.
Figure 5: Balance -30%; wire feeding 12m/min.
Figure: 6: Clad layer in the cross-section polish.
Figure 7: Test piece E19, cross-sectioned and polished, along
with the dilution calculations.
Figure 8: Robot on robot welding trials of the Bushmaster hull.
In further trials, itwaspossible todetermine theeffect of
the dc TIGwith ac hotwire technique on the distribution of
carbides in a hard surfacing operation. For wear protection,
it is important that the carbides are not destroyed during
the welding process and are present in fine distribution in
the surfacing following treatment. Only in this way can a
wear-resistant and durable surfacing be achieved. Thanks
to this new alternative process it is nowpossible, at deposi-
tion rates of up to6,0 kg/h, to achieve an abrasive-resistant
clad surface with finely distributed carbides. In the trial, a
tungstencarbide flux-coredwirewasappliedonanunalloyed
structural steel using the identical test rig.
In practice, this welding process is being accepted on
the strength of the positive trials. One international pipe
manufacturer is applying abrasive- and chloride-resistant
functional layers onto the inside of large-diameter, unal-
loyed structural steel pipes using an automated system. In
this example, 12 welding torches are attached to a lance
with filler wire to apply functional layers to individual pipe
segments of lengths of up to 12m. The alternative dc TIG
with ac hotwire process has enabled this manufacturer to
shorten cycle times measurably, by 30%, while increasing
the quality and durability of the functional layer.
Outlook
At a time of ever-increasing demand for rawmaterials and
primary energy, sustainable and resource-conserving ap-
proaches are becoming considerablymore important. Many
businessenterprisesarealready taking responsibility forbetter
handling of rawmaterials and energies and the conservation
of the environment very seriously. By virtue of its savings in
overall energy demand, due to shortermanufacturing times,
a reduction innon-productive times due tonon value-adding
activities anda significantly improvedwelding outcome, this
newweldingprocess isalsocontributing toacost-conscious,
sustainable and resource-conserving overall process.
Australian examples of sustainable innovative
welding and cutting processes
Roboticwelding isnotnew inAustralia. Ithasbeenused in the
automotive and manufacturing industries since the 1970s.
AlthoughAustraliahas not beena leader in thedevelopment
of robotics, it hasproducedsome innovativeapplications that
areworld leading. This section describes a number of these
welding and plasma cutting applications.
Robot welding of large fabrications took a major step
forward when a robot system was developed by Robot
Technologies Australia (RTA) for Thales to weld the hulls
of Bushmaster armoured personnel carriers for the Austra-
lian defence forces. The Bushmaster hull weighs 7,0 t, is
7,0m long and involves about 600m of welding, inmany
instancesmulti-pass.Hull sideshavenumerouspenetrations
andwelded attachments that distort the high strength steel
plate. Thehull isassembledand tack-welded, thenplaced in
a positioner that can bemanipulated through 360°.
To gain access to the internal welds, the robot cell uses
standard 6,0 kg payload robots mounted on large 300 kg
pick andplace robots. (
Figure8
). These robots run on10m
tracks (shifters). The key to success using this configuration
is theuse of laser joint location and tracking. RTAdeveloped
algorithms that shift the robotpathbasedon the laser location
data. Once welding commences, laser tracking adjusts the
robot path in real time. Smaller robotsareused forpreheating
the armour steel andmonitoring its temperature.
Robotweldingof theBushmastershas increased through-
put by 400% and has secured the viability of manufacture
in Australia. For the small family owned RTA business, this
was a significant achievement.
BOC beganmarketing EWMwelding equipment in early
2010 andpartneredwithRTA and other robot integrators to
supply turnkey automated welding systems. In 2012, BOC
