53
Chapter 5
W
elding Operation
C
HECK
BEFORE
W
ELDING
W
ELDING
O
PERATION
C
HAPTER
5
6
The contact part of jig and welding work piece
should not be painted.
Painted contact part could cause increased contact resistance, resulting in
decrease in arc voltage. Polish the painted contact part using a grinder to expose
the metal face.
7
The contact part of jig and welding work piece
should be free from unevenness due to
influence of burn through, spatter, or aging
deterioration.
Polish the surface of the jig using a grinder so that the welding workpiece and the
jig can fully contact each other.
8
The mixing ratio of shielding gas should be
adequate.
High CO
2
- concentration could increase the spatter generation.
For shield gas, follow the mixing ratio as follows:
CO
2
gas
:
Carbon dioxide (CO
2
) 100 %
MAG gas
:
Argon (Ar) 80 % + Carbon dioxide (CO
2
) 20 %
MIG gas (Stainless)
:
-
Argon (Ar) 98 % + Oxygen (O
2
) 2 %
MIG gas
(Aluminum/Aluminum
bronze/Silicon bronze)
:
Argon (Ar) 100 %
9
The shield gas should be correctly mixed.
Use a mixer. If welding is unstable, use pre-mix gas to check if the welding
condition is improved. High CO
2
concentration could increase spatter generation.
10 The flow rate of shield gas should be adequate.
Ensure the adequate shield gas flow rate as follows:
CO
2
/MAG gas
MIG gas
TIG welding
:
:
:
21 to 53 CFH (10 to 25 L/min)
32 to 53 CFH (15 to 25 L/min)
11 to 32 CFH (5 to 15 L/min)
11
When the shield gas is mixed, each gas
pressure should be the same.
Set pressures of the respective gas to the same level.
12
Oil or other dirt should not be adhered on the
welding wire.
Consider a measure to wipe off the dirt and to perform degreasing.
13
In the CO
2
- and MAG welding, the particle
diameter of wire tip at the welding completion
should not excessively be large or small.
Adjust anti-stick voltage so that the wire tip particle size becomes 1.2 to 1.5 times
of the wire diameter. If the particle size is smaller than the above, set the anti-stick
voltage to a higher value, whereas if the particle size is larger than the above, set
the anti-stick voltage to a lower value.
14
At start point of welding, the tip of welding wire
and the welding workpiece should not be
contacted.
(When using a robot, operate several times with
"welding OFF" and confirm that the welding wire
and the welding workpiece do not contact each
other.)
If the wire tip contacts with the welding workpiece, set anti-stick voltage to a higher
value to increase meltage of the welding wire at the end of welding.
If anti-stick voltage is set to a value higher than the appropriate range, the wire tip
particle size becomes excessively large, resulting in poor start performance of the
next welding.
15 The tip of the welding torch should not be worn.
Visually check the hole diameter of the tip. If it is 1.2 times or larger than the hole
diameter of a new tip, or when the tip is discolored, replace it with a new one.
16
In wire feeding, pressure roll should not be idled
and the wire reel should rotate smoothly.
Adjust the pressure level of wire feeder. If it is not improved, check for other factor
that generates overload on wire feeding. (
See parameter 12, 17, 18)
17 The groove of feed roll should not be dirty.
Clean the dirty groove with a wiry tool.
18
There should be no large feeding resistance of
wire.
(With the pressurized holder of the wire feeder
held up, hold the tip of welding wire with a plier,
and try pulling it out; if smoothly pulled out, it is
adequate.)
Ensure that the torch cable has no bending at a sharp angle.
If the liner is clogged with dirt or when inched wire has flaw, replace the liner with
a new one.
(In replacing the liner, follow the precautions on the attached manual of welding
torch for appropriate handling.)
In cutting the liner, take care for the followings:
If the liner is too long: feeding resistance increases, resulting in shorter life of wire
feeder.
If the liner is too short: feeding failure occurs.
Check parameter
Countermeasures
Check
