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