SHIELDED METAL ARC WELDING
1.) SMAW Process
SMAW process defined as an arc welding process which produces coalescence of metals by heating them with an arc between a covered metal electrode and the work-piece. Shielding is obtained from decomposition of the electrode covering.
Pressure is not used and filler metal is obtained from the electrode.
2.) MODE OF OPERATION
Arc melts parent plate and electrode to form a weld pool which is protected by flux cover. Operator adjusts electrode feed rate, I.e. hand movement to keep arc length constant. Slag must be removed after depositing each bead. Normally a small degree of penetration, requiring plate edge preparation. Butt welds in thick plate or large fillets are deposited in a number of passes.
The process can also be used to deposit metal to form a surface with alternative properties.
3.) SMAW -OPERATING PARAMETERS
Current range :75-300 A
Range of Thickness: 2mm upwards
Deposition rate :2-11 lb/Hr
Types of joint : All
Welding position : all (depending on flux coating)
4.) OVERALL ADVANTAGES
- Low Equipment Cost
- Usage possible with restricted access.
5.) OVERALL LIMITATIONS
- Skilled operator is required for good quality welds.
- Slow, mainly because flux must be chipped away.
- Arc emits visible and ultraviolet radiation.
- High open circuit voltage present while electrode is fitted to holder