EXPERIMENTAL PROCEDURE AND APPARATUS
1. The power supply is switched on
2. Power source is switched on and is set to 15-28V
3. The gas regulator is opened, counter clock wise (CCW), the gas pressure is checked.
4. The flow meter is opened, counter clock wise (CCW), the flow rate is checked to 10-15LPM
5. The trigger mode is selected 2T
6. The function is selected.
7. The Wire Feed Speed (WFS) is selected to 4m/min.
8. The current (A) is set to 3-2 for thick material.
9. The return cable is clamped at the work piece
APPARATUS
Gas tank
Gas pressure reading Flow rate
reading
Flow meterGas regulator
Control setting
Figure 3
Figure 2Figure 1(GMAW Machine)
RESULT
INDUSTRIAL APPARATUS
GMAW machine for aluminum welding
MIG Welding Machine
Portable welding system for GMAW, SMAW, GTAW
DISCUSSION
From this laboratory, GMAW, Gas Metal Arc Welding has been conducted in this experiment. Basically
GMAW is quite different compared to SMAW, Shield Metal Arc Welding. GMAW the electrode is a roll of
wire which the welder feeds out of a ‘gun’ to the work piece. The speed of the wire can be control, so it
can make long welds without stopping to replace a rod. This type of welding is generally considered to
be the easiest to learn. The gun also feeds out an inert gas such as Argon or CO2 to displace oxygen at
the weld site. GMAW has no slag to be chip away because of the feed inert gas.
From the result, it shows that the welding bead is not perfect and there are some defects occur during
the welding. There are several causes the influence the defects of the welding bead such as Voltage (V),
Current (A), and welding speed (m/mm). For voltage, the voltage is needed to be constant. The power
source will supply the necessary amperage to melt the welding electrode at the rate required to
maintain the present voltage or relative arc length. The speed of the electrode drive is used to control
the average welding current. The use of this type of power supply in conjunction with a constant wire
electrode feed results in a self-correcting arc length system.
For current, the current also needed to be constant. Arc length (voltage) is controlled by the automatic
adjustment of the electrode feed rate. This type of welding is best suited to large diameter electrodes
and machine or automatic welding, where very rapid change of electrode feed rate is not required. Most
constant current power sources have a drooping volt-ampere output characteristic. Constant current
power sources are not normally selected for MIG welding because of the control needed for electrode
feed speed. The systems are not self-regulating. For welding speed, it will affect the welding bead
characteristics. If the welding speed increase, the welding bead’s width and height will decrease, while
the depth will increase.
CONCLUSION
As the conclusion, GMAW is the type of welding generally considered to be the easiest to learn. It
allowed for lower welding time compared to other welding processes. It is also operated in
semiautomatic, machine, and automatic modes and is utilized particularly in high production welding
operations. All commercially important metals such as carbon steel, stainless steel, aluminum, and
copper can be welded with this process in all positions by choosing the appropriate shielding gas,
electrode, and welding conditions. In order to gain perfect outcome of the welding bead, a precaution of
the welding technique must be done. The defects and quality of the welding bead can be controlled with
good technique of welding and standard operation procedure.
RECOMMENDATION
Lack of fusion
Increase arc power
Adjust welding speed
Weld vertical up
Change the arc angle
Porosity
Check gas type and coverage
Ensure weld piece and filler is dry
Check parent material and joint face
Check manufactures specification
Slag Inclusion
Increase arc power
Shorten arc length
Prepare and clean joint
Aim arc towards the molten pool
Spatter
Adjust the welding parameters
Change polarity
Check filler materials and storage conditions
Check gas coverage and type