Deposition Rate
Overcoming the Problem of Oxygen
Contamination
Powder deposition rates are very low and average
0.1 kg/hr. With advancing technology this may well
The issue of adequate protection has been resolved
increase but at the present time this severely restricts by developing flexible enclosures that can be purged
applications. The wire arc process is capable of laying with inert gas, usually argon. These can accommodate
down 10 kg/hr of a wide range of metal alloys. [Table 1.] the entire welding equipment and robot and provide
inert gas protection throughout the deposition
Process Limitations
process.
Many alloys may be used during the WAAM process
simply by using the welding torch inert gas shroud as
protection. However, some materials are much more
prone to reaction with residual oxygen and this can
lead to fusion zone and surface oxidation. Titanium
alloys are particularly sensitive but stainless steels.
and many low alloy steels also demand additional
inert protection.
With the electron beam process, protection is
assured since operations are carried out in a vacuum.
Nevertheless, this is an expensive alternative to arc
welding.
Flexible Enclosure Technology
There have been considerable advances in enclosure
development since the concept was introduced over
two decades ago. Huntingdon Fusion Techniques
Ltd [Ref: 10] for example has spearheaded a drive
to design systems specifically for the welding
industry. These innovative products offer significant
attractions over both vacuum and glove box
alternatives not least a significant reduction in cost.
The largest facility to date has a volume of 27 m3,
adequate to accommodate all work-pieces, welding
equipment and even a programmable robotic
TUBE NEWS
ยป
June 2019
11