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Here is a list of the key
benefits of the tailored root
pass welding process:
• Wider root gap makes it possible
to use a smaller groove angle and
decrease groove volume.
• No need to use a backing ring.
• It is a highly efficient process:
10 % faster than normal MAG
welding, and three times faster
than TIG welding.
• It is suitable for position welding
• Easy to learn and use.
• Less spatter than in normal short
arc.
Process
v [mm/
min]
wfr [m/
min]
I [A] U [V] P [W] Q [kj/
mm]
Q [%]
WiseThin 800 4 93 16,7 1517 0,091 0
1-MIG 800 4 113 18,3 2028 0,122 25,20
Table 1: WiseThin and synergic MIG heat input comparison
Picture 3: Low heatinput
and optimal
weld bead geometry
are among the
benefits of tailored
processes.
On the workshop level, the above
WiseRoot features can be seen as
increased welding quality and decreased
need for post-weld rework.
The WiseThin process for sheet
metal welding
In sheet metal welding, low heat input
is a desirable feature. There are various
laser welding applications that have been
used for this purpose, but lasers have their
limitations.
MIG/MAG welding has developed
so that it is now possible to weld with
low heat input, especially in the short-arc
area. In tailored processes, one can obtain
the same heat input as in laser welding.
Kemppi’s WiseThin is a tailored
MIG/MAG short-arc process that enables
achieving 5–25 % less heat input than
with a normal short arc, depending on the
welding case. In welding of high-strength
steels, this is of great benefit, because
the trend is to weld steels of ever higher
strengths. This is a driver toward a weld
process with low heat input.
Table 1 compares the WiseThin
process’s heat input to the heat input of a
normal short arc in welding of an overlap
joint. The material is structural steel and
the plate thickness 1.0 mm.
The principle of the WiseThin
process is similar to that of the tailored
WiseRoot process for root pass welding.
The difference is that the WiseThin is
optimised for sheet metal welding.
WiseThin is a modified short-arc
welding process and as a MIG/MAG
welding process it is in category 131,
133, 135 or 138 as defined in the EN ISO
4063 standard.
Picture 3 shows typical welding
applications for tailored sheet metal
welding processes.
In sheet metal laser welding
applications, the biggest problems arise
from the narrow gap tolerances. With
MIG/MAG processes the tolerance
window is wider, because they are not
so sensitive to gap variations. Tailored
processes can increase the width of the
gap tolerance window, because of the
lower heat input. This makes it easier to
handle molten metal.
24 Kemppi ProNews 2011