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STEALTH DIGI-ARC 160PFC MV
15
4.4.2 Electrode selection
Electrode diameter selection is based on the workpiece thickness, welding
position, joint form, welding layer, etc. Please refer to the following table.
• Electrode should be drying according to user manual before using. For reducing
the hydrogen of the molten pool and welding seam, and avoiding the blowhole and
cold crack.
• In the welding process, the arc must not be too long otherwise it will cause
unstable arc burning, large spatter, light penetration, undercut, blowhole, etc.
If the arc is too short, it will cause electrode stick.
• In MMA welding the arc length is usually equal to 0.5~1.0 times of the electrode
diameter. The basic electrode’s arc length is not beyond the electrode diameter, it’s
better to choose the short arc welding; the acid electrode’s arc length is equal to the
electrode diameter.
OPERATION CONTROL AND CONNECTORS
12
current and operation skill, etc.
The details please refer to
《
Welding Dictionary
》
P69, Volume 1 of Edition 2.
§
4.4 Welding parameters
§4.4.1 Joint form in MMA
In MMA welding, the common basic joint form: butt joint, lap joint, corner joint
& T joint.
§4.4.2 Electrode selection
The electrode diameter selection is based on the workpiece thickness, welding
position, joint form, welding layer, etc. Please refer to the following table.
The welding current reference for different electrode diameter
Electrode
diameter/mm
1.6
2.0
2.5
3.2
Welding current/A
25
~
40
40
~
60
50
~
80
100
~
130
The relation between the welding current(I)’ factor(K) & electrode diameter(d) (I
=
K
×
d: Carbon electrode)
Electrode
diameter/mm
1.6
2
~
2.5
3.2
Factor/K
20
~
25
25
~
30
30
~
40
Notice: the above parameters originate from
《
Welding Dictionary
》
P66
~
P67, Volume
1 of Edition 2.
l
Electrode should be drying according to user manual before using. For reducing
the hydrogen of the molten pool and welding seam, and avoiding the blowhole
and cold crack.
l
In the welding process, the arc must not be too long; otherwise, it will cause
unstable arc burning, large spatter, light penetration, undercut, blowhole, etc. If
the arc is too short, it will cause electrode stick.
l
In MMA welding the arc length is usually equal to 0.5~1.0 time of the electrode
butt joint
lap joint
corner joint
T joint
4.5 Arc Welding Defect and Prevent Method
OPERATION CONTROL AND CONNECTORS
13
diameter. The basic electrode’s arc length is not beyond the electrode diameter,
it’s better to choose the short arc welding; the acid electrode’s arc length is equal
to the electrode diameter.
§
4.5 Arc Welding Defect and Prevent Method
Defect name
Caused reasons
Prevent methods
Welding seam
doesn’t meet
the requirement
The groove angle is not proper
The root face and assembly gap is not equal
Welding technics parameters are unreasonable
The welder’s operation skill is lower
Choosing the proper groove angle & assembly
gap, improve the assembly quality
Choosing the proper welding parameters
Improve the operation skill of welders
Undercut
Over current
Arc length is too long
The electrode angle is wrong
Manipulation of electrode is not proper
Choosing the proper welding current & speed
The arc can’t be drawn too long
The electrode angle should be proper
Manipulation of electrode should be correct
Incomplete
penetration
The groove angle or gap is too small, the root
face is too big
Welding parameters are not suitable, or the
assembly is not good
The welder’s operation skill is lower
Correctly to choose and process the groove size
Correctly to assemble and ensure clearance
Choosing the suitable welding current & speed
Improve the operation skill of welders
Incomplete
fusion
The welding thermal input is too low
The arc direction is lean
There are rust & dust on the side of groove
The slag between the layers is not cleared well
Correctly to choose the welding parameters
Operation seriously
Enhance the clearness of layers
Overlap
The temperature of molten pool is too high
The liquid metal concretes slowly
Choosing parameters based on the welding
different position
Strictly to control the molten hole size
Crater
The crater time lasts too short
Over current in the welding of thin plate
In the crater, electrode should be stayed for a
short time or round to manipulate electrode
after the molten pool is filled in by metal, take
to the side for crater
Blowhole
There are some dust like oil, rust or water on
the work piece surface and groove
The coating of electrode is damped& is not
drying
Under current or over speed in the welding
The arc is too long or lean burning, the molten
pool protection is not good
Over current, the coating of electrode falls off
and lose protection
Manipulation of electrode is not proper
Clear out the dust around groove for about 20
~
30mm
Strictly to dry the electrode according to manual
Correctly to choose parameters and to operate
Using the short arc operation
Welding operation in the field should have
anti-wind protection
Don’t use the invalid electrode
Inclusion &
slag inclusion
The slag clears bad in the middle layer in the
welding process
Choosing the electrode of good slag
detachability
Summary of Contents for DIGI-ARC 160PFC MV
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