(A) Electrode size and welding current
0.8, 1.0, 1.2, 1.6 and 2.4 mm diameter wires. The selection of electrode size depends upon the thickness of the workpiece to be welded as given below:
| Workpiece thickness (mm) | Wire diameter (mm) |
| 1.0-2.0 | 0.8-1.0 |
| 2.0-4.0 | 1.0-1.2 |
| 4.0-8.0 | 1.2-1.6 |
| 8.0 above | 1.6 above |
Welding current
Welding current is selected according to
(i) Electrode size.
(ii) Base metal or workpiece thickness.
(iii) Type of metal transfer.
(iv)Electrode feed speed.
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(B) Arc voltage
As arc length increases, arc voltage increases and in turn welds width increases but penetration reduces. Arc voltage is important because it also determines the type of metal transfer. Arc voltage to be used depends upon:
(i) Workpiece thickness,
(ii) Type of joint,
(iii) Electrode size and its composition
(iv) Shielding gas,
(v) Welding position, etc.
The arc voltage is kept low for achieving short circuit or dip transfer whereas its value is higher for globular type of metal transfer. To reach at a precise value of arc voltage, one should carry out trial runs, because no specific values are appropriate for all applications. Thin steel sheets Semi automatic and automatic welding of medium thicknesses Automatic welding of thick sections in flat position.
| Arc Voltage | Type of Metal Transfer | Remarks |
| 16-22 | Short circuiting | Thin steel sheets |
| 24-30 | Both spray and short circuiting | Semi automatic and automatic welding of medium thickness |
| 30-45 | Spray | Automatic welding of thick sections in flat position |
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(C) Arc travel speed
The speed (cm/min) at which the arc moves along the joint to be welded is termed as arc travel speed. As arc travel speed increases, weld penetration reduces and vice versa. Weld bead width is more at reduced arc travel speed. Undercutting occurs at excessive arc travel speed.
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| (D) Electrode extension or stick out It is the distance between the end of the contact tube and the tip of the electrode. Generally the stick-out may be between 16 and 19 mm. However: With too short stick-out, excessive spatter gets deposited on the nozzle thereby restricting the shielding gas flow and causing porosity. If stick out is too long, a badly shaped weld and shallow penetration may result. Arc stability is also affected. | |||||||
