Two companies have successfully commercialized a specialized welding
tool developed at NASA’s Marshall Space Flight Center in
Huntsville, Ala.
Commercialization of auto-adjustable pin tool technology – used
in the friction stir welding process – marks another success for
NASA’s technology transfer program. The program seeks to
stimulate broad use of NASA-developed technologies by American private
enterprise.
Friction stir welding uses the high rotational speed of a tool and the
resulting frictional heat created from contact to crush,
“stir” together, and forge a bond between two metal
alloys. The technique is more reliable and maintains higher material
properties than conventional welding methods. However, friction stir
welding has had a major drawback – reliance on a single-piece
pin tool. The pin is slowly plunged into the joint between two
materials to be welded and rotated at high speed. At the end of the
weld, the single-piece pin tool is retracted and leaves a
“keyhole,” something which is unacceptable when welding
cylindrical objects such as drums, pipes and storage tanks. Another
drawback is the requirement for different-length pin tools when
welding materials of varying thickness.
To overcome these drawbacks, a Marshall Center welding engineer helped
design an automatic retractable pin tool that uses a
computer-controlled motor to automatically retract the pin into the
shoulder of the tool at the end of the weld – preventing
keyholes. This design allows the pin angle and length to be adjusted
for changes in material thickness and results in a smooth hole closure
at the end of the weld.
MTS Systems Corp., a leading supplier of mechanical testing and
simulation equipment based in Eden Prairie, Minn., recently introduced
an advanced friction stir welding process system employing
Marshall’s retractable pin tool technology. Use of the tool by
MTS has resulted in applications that are cost-competitive, efficient
and versatile for automotive, shipbuilding and other industries. This
Marshall technology also has helped the company gain market share in
the growing friction stir welding niche and develop additional
business relationships.
Another company, MCE Technologies, Inc., (MCETEC) of Seattle, has
developed a cutting-edge line of production stir welding equipment
that uses Marshall’s retractable pin tool technology to provide
flawless welds in high performance aluminum alloys, including those
previously thought unweldable. The company’s use of the
retractable pin tool has contributed to production advantages
including minimal material distortion, lack of contamination and
greater joint strength for friction stir welding applications in
aerospace and other industries. Additionally, working with the
Marshall Center has helped MCETEC remain a stable employer by
improving its product offering to the friction stir welding market.
Applications for friction stir welding include aircraft, aerospace,
marine shipbuilding and decks for car ferries, trucking, railroading
and assembling large tank structures such as fuel tanks and
radioactive waste containers.
Benefits of friction stir welding, using the Marshall Center’s
retractable pin tool technology, include:
Diverse materials: Welds a wide range of alloys, including previously
unweldable and composite materials.
Durable joints: Provides twice the fatigue resistance of fusion welds
and no keyholes.
Retention of material properties: Minimizes material distortion.
Safe operation: Does not create hazards such as welding fumes,
radiation, high voltage, liquid metals or arcing.
No keyholes: Pin is retracted automatically at end of weld.
Tapered-thickness weld joints: Pin maintains full penetration.
For more information on NASA and the Marshall Center’s
technology transfer program, visit the Website:
