Friction Stir Additive Manufacturing—A Review
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in the aerospace industry. Furthermore, as mentioned earlier, the Hall–Petch strengthening ability [75, 76] in addition to the welding defects occurring due to fusion
processes makes this technology ideal for additive manufacturing of lightweight Mg
alloys, titanium alloys and steels.
FSAM also creates the possibility of fabricating graded structures of multiple
materials/alloys along with welding single alloy structures. Traditional additive
manufacturing (AM) techniques face challenges in the context of manufacturing
graded components due to difference in thermomechanical properties, thermal expansion coefficients and melting points. Also, the formation of undesirable inter-metallic
compounds (IMCs) erodes the strength of the welds [87]. These problems can be
circumvented through FSAM. The thermal expansion problem is avoided since there
is no melting and only localized heat transfer owing to solid-state nature of FSAM,
while the intense plastic motion and shearing action help distribute and control the
size and uniformity of IMCs at the interface.
Tantalizingly FSAM processes can also create custom materials and alloys in a
single process. These processes can also manipulate the composition of the alloys
and microstructure by dictating the mixing of materials. Friction deposition is a
promising technique for creating alloys and new materials in the weld pool itself.
Thus, FSAM can be considered one of the most feasible techniques for the production
of functionally graded components if not the best.
4.3 Industrial Impact
FSAM is a relatively new process at the industrial scale. The applications for it are in
aerospace and defence. This technique can pave the way for efficient manufacturing
of high-strength structural parts for aircraft and other technical parts. Also, large parts
can be manufactured with these processes, and they can also be used for fabrication
of entire structures of satellites and spacecraft. Production of stiffeners/stringers for
the aviation industry is one of the pertinent applications of FSAM in aerospace.
Potential of FSAM in the aerospace industry has been supported by the reports of
Boeing [36] and Airbus 2006 [52]. They have concluded that FSAM can be used to
achieve higher efficiency in terms of productivity and material loss.
The developments in the friction stir welding are directly translated to the developments in this technology because their fundamental process is analogous. The FSW
technique was invented by TWI in 1991, and there are 3294 patents (from 1993 to
2014) [88] registered considering this technology by various industries. Hitachi has
214 related patents, and Boeing has 67 and there are around 172 license holders
for the TWI patents [89]. The industrial groups that already have access to FSW
technology are the forerunners in commercializing 3D printing FSAM technologies.
Groups such as UTC have patents on FSAM systems [89].
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in the aerospace industry. Furthermore, as mentioned earlier, the Hall–Petch strengthening ability [75, 76] in addition to the welding defects occurring due to fusion
processes makes this technology ideal for additive manufacturing of lightweight Mg
alloys, titanium alloys and steels.
FSAM also creates the possibility of fabricating graded structures of multiple
materials/alloys along with welding single alloy structures. Traditional additive
manufacturing (AM) techniques face challenges in the context of manufacturing
graded components due to difference in thermomechanical properties, thermal expansion coefficients and melting points. Also, the formation of undesirable inter-metallic
compounds (IMCs) erodes the strength of the welds [87]. These problems can be
circumvented through FSAM. The thermal expansion problem is avoided since there
is no melting and only localized heat transfer owing to solid-state nature of FSAM,
while the intense plastic motion and shearing action help distribute and control the
size and uniformity of IMCs at the interface.
Tantalizingly FSAM processes can also create custom materials and alloys in a
single process. These processes can also manipulate the composition of the alloys
and microstructure by dictating the mixing of materials. Friction deposition is a
promising technique for creating alloys and new materials in the weld pool itself.
Thus, FSAM can be considered one of the most feasible techniques for the production
of functionally graded components if not the best.
4.3 Industrial Impact
FSAM is a relatively new process at the industrial scale. The applications for it are in
aerospace and defence. This technique can pave the way for efficient manufacturing
of high-strength structural parts for aircraft and other technical parts. Also, large parts
can be manufactured with these processes, and they can also be used for fabrication
of entire structures of satellites and spacecraft. Production of stiffeners/stringers for
the aviation industry is one of the pertinent applications of FSAM in aerospace.
Potential of FSAM in the aerospace industry has been supported by the reports of
Boeing [36] and Airbus 2006 [52]. They have concluded that FSAM can be used to
achieve higher efficiency in terms of productivity and material loss.
The developments in the friction stir welding are directly translated to the developments in this technology because their fundamental process is analogous. The FSW
technique was invented by TWI in 1991, and there are 3294 patents (from 1993 to
2014) [88] registered considering this technology by various industries. Hitachi has
214 related patents, and Boeing has 67 and there are around 172 license holders
for the TWI patents [89]. The industrial groups that already have access to FSW
technology are the forerunners in commercializing 3D printing FSAM technologies.
Groups such as UTC have patents on FSAM systems [89].