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Users increasingly demand complete absence from
discolouration and no loss of corrosion resistance and
this implies purge gas oxygen content to be as low as
20 ppm (0.002%). Very few oxygen purge monitors
are capable of meeting this sensitivity but the PurgEye
[Figure 7] instruments cover all requirements.
Conclusion
Figure 6. The robot/enclosure interface is effectively
sealed against leaks using an adaptable occlusion.
Enclosures up to 27 m3 volume have been
manufactured to accommodate large systems
A crucial benefit of 3-D printing is that it opens up
possibilities for the production of complex designs
that otherwise might not be practical or economic.
In terms of applications for WAAM and DMLS/
DMEBS the welding version is most suitable for
heavier and larger products whilst the powder
alternative is best applied where smaller, delicate
objects are required. In other words, welding is
essentially a bulk deposition technique and powder is
a precise and highly controlled process.
Many alloys need to be protected from contamination
during the welding operation. The formation of
metallic oxides can reduce corrosion resistance and
affect mechanical properties. The use of an effective
oxygen-free inert gas environment is essential.
.
References
Figure 7. Advanced oxygen monitor includes full
colour touch screen control. The instrument supports
data logging and weld certification. Readings are
accurate down to 10 ppm.
system. By purging the enclosure with inert gas an
operating oxygen content is low enough to prevent
oxidation during welding and cooling. [Figure 6]
Monitoring the Oxygen Content
Control and real-time monitoring of the oxygen
content of the purge gas is crucial if discolouration
and loss of corrosion are to be avoided. Techniques
for measuring oxygen content have been available
for decades but only recently have instruments
been developed specifically for welding applications.
12 TUBE NEWS June 2019
1. Cancer patient receives first 3D printed sternum and rib
cage. Orthopaedics and Spine, July 2017.
2. Direct metal laser sintering, Bertol et al, Materials &
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3. Laser-Based Additive Manufacturing Processes.
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4. World’s first class approved 3D printed propeller.
International Institute of Marine Surveying, May 2017.
5. Design for Wire and Arc Additive Layer Manufacture.
Mehnen et al. 20th CIRP Design Conference, Nantes
April 2010.
6. Wire & Arc Additive Manufacturing. Williams et al,
Materials Science & Technology 2016 Vol 32
7. Williams S. WAAM Current and Future Developments.
Additive Manufacturing for Aerospace, Defence and
Space conference. London, March 2016.
8. Damen shipyards release further details about world’s
first 3D printed propeller. 3D Printing Industry.
September 2017.
9. Wire+arc additive manufacturing vs. traditional
machining from solid: a cost comparison. Martina F.
10. Huntingdon Fusion Techniques Ltd, UK