|
Swing FSW is Hitachi's unique method of implementing
spot welding using FSW. Similar to linear FSW, a
rotating tool plunges into the work piece that are to be
joined. Once the desired plunge depth is reached the tool is
held stationary at that position for a predetermined amount
of time. Then,
while the tool is still plunged into the work piece, it is
made to traverse linearly for a short amount of distance
(which is called as swing-length) after which the tool
retracts away from the work piece. This process is
also called stitch welding. The advantage of swing FSW
is better mechanical strength when compared to conventional
spot welding.
This process is further illustrated in the adjoining figure.
The figure on the top shows conventional FSW spot weld where
the tool plunges in and retracts back along the same axis
(shown in magenta)
The figure below that shows Hitachi's swing FSW concept.
The magenta line with the arrow head tracks the position of
the tool. First, the tool plunges into the work piece
where it is held for a finite amount of time. Then instead
of retracting back up, the tool 'swings' in a linear
direction (in this case from left to right) to achieve a
stitch weld. The amount of traverse is called the swing
length. After the desired swing length has been achieved,
the tool is held in that position for a finite amount of
time after which it is retracted back up.
 
Unique Features:
-
Good process
repeatability
-
No porosity
or solidification cracking
-
Weld region
has a finer grain structure than the base metal
-
Excellent
mechanical properties
-
Swing length
increases the joint strength
-
Higher
strength than resistance spot welding (RSW)
|
