Interview question from GMAW process
What is GMAW Welding?
·
Dip Transfer
·
Spray Transfer
·
Pulsed Transfer
·
Synergic Pulsed Transfer
·
Globular Transfer
What are the variable parameters in GMAW Process?
·
Voltage
·
Wire feed speed
·
Gases
·
Inductance
What types of possible welding imperfections may occur in
GMAW process?
·
Silica inclusions (On
ferritic steels)
·
Lack of sidewall fusion
·
Porosity
·
Burn through
Give any five advantages of the GMAW process?
·
High Productivity
·
Easily automated (Robotics)
·
All positional
·
Wide material thickness
range
·
Continuous electrode
Give any five disadvantages of the GMAW process?
· The small range of solid wires
·
Protection for site working
·
Complex equipment
·
High ozone levels
What is the current range for the following metals in
GMAW process?
a) Carbon steel b)
Stainless steel c)
Aluminum
Material
|
Arc current (Amps)
|
Electrode Día(mm)
|
Shielding gas
|
Flow rate of Shielding gas
|
Carbon Steels (Double V butt)
|
400 DCRP
|
1.5
|
Argon+25%CO2
|
6 to 12
|
Stainless Steel (Butt)
|
275-350 DCRP
|
1.5
|
Argon +1%O2
|
15 to20
|
Aluminum (Square butt)
|
200-225 DCRP
|
1 -1.25
|
Argon
|
18
|
What is the different size of electrodes in the GMAW Process?
0.8mm,1.2mm,1.6mm, etc.
What type of materials can be welded by GMAW Process?
·
Carbon and low alloy steels
·
Stainless steels
·
Heat-resisting alloys
·
Aluminum and its alloys
·
Copper and its alloys (other
than high zinc alloys)
·
Magnesium alloys
What are the various types of welding joints used in the GMAW Process?
·
Butt joint
·
Lap joint
·
T joint
·
Corner joint
·
Edge joint
Describe the GMAW Process Applications?
The GMAW process can be used for the welding of the following metals:
·
carbon,
·
silicon, and low alloy
steels,
·
stainless steels
·
aluminum,
·
magnesium,
·
copper,
·
nickel and their alloys,
·
titanium, etc.
·
tool steels and dies.
·
For the manufacture of
refrigerator parts.
·
Aircraft,
·
Automobile,
·
Pressure vessel,
·
Ship buildings.
What is the function of
Shielding gases in GMAW Process?
The function of shielding gas in
GMAW Process is to protect the molten metal and the electrode end from
atmospheric contamination.
How many types of shielding
gases are used in GMAW Process?
Shielding Gases
|
Metal to be welded
|
Argon
|
of Al, Mg, Cu, Ni, Ti
|
Helium
|
Al, Mg, Cu
|
Carbon dioxide
|
Mild steel
|
Nitrogen
|
Copper
|
Argon+(1-5 %) Oxygen
|
Al, low alloy and Carbon steels, stainless steels
|
Argon +CO2
|
Mild steel ,low alloy and stainless steel
|
Argon+Helium+CO2
|
Austenitic stainless steels
|
Argon + Helium
|
Al, Cu, Ni
|
What are the function of solenoid valves and relays in
GMAW Process?
solenoid valves and relays may be incorporated in the system
to put on and off gas, water and wire feed mechanism.
QUESTION FROM CO2 WELDING
What is the CO2 Welding process?
CO2 Is basically a Sami-automatic process, in which the arc
length and the feeding of the electrode wire into the arc are automatically controlled.CO2
is used as an active gas (for shielding purpose) in this process.
What type of electrode should be used when co2 is used as
shielding gas?
When using CO2 as the shielding gas the electrode wire must
contain deoxidizer such as manganese and silicon that readily combine with the
oxygen and prevent it from combining with the weld metal.
Describe the welding current range, different size of
electrodes, and selection of electrodes upon the thickness of the base metals in
CO2 Welding process?
Welding current range for various range of electrodes are as
follows:
Electrode size(mm)
|
0.08
|
1.0
|
1.2
|
1.6
|
2.4
|
Current range (Amps)
|
50-100
|
70-120
|
90-150
|
140-300
|
300-700
|
Describe the thickness of the base metals, according to
the current range, also choose the size of the electrode.
Workpiece thickness(mm)
|
1.0-2.0
|
2.0-4.0
|
4.0-8.0
|
8.0 and above
|
Wire diameter(mm)
|
0.8-1.0
|
1.0-1.2
|
1.2-1.6
|
1.6 and above
|
How many factors are responsible for selecting the
welding’s current in the CO2 Welding process?
The welding current is selected according to:
·
Electrode size
·
Electrode feed speed
·
Type of metal transfer
·
Base metal thickness
Give any four advantages of the CO2 welding process?
·
Higher welding speed
·
Deep penetration with good
weld bead
·
Good mechanical properties
of the weld metal
·
Sound weld deposits which
can be made consistently
What are the limitations of the CO2 welding process?
- · Carbon dioxide is producing a rather harsh arc
- · Excessive spatter unless a very short, uniform arc length is maintained
- · High impact properties in the weld metal cannot be achieved.
Which of the following gases can be used as shielded gases in GMAW?
a- Carbon
dioxide b-Argon –oxygen
c-Argon-Carbon
dioxide d-Argon
e-All of the above
e- All of the above
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