Shielded Metal Arc Welding: An Introduction

Shielded Metal Arc Welding Defined: The Shielded Metal Arc Welding process is a consumable welding process where an arc is generated between the grounded work-piece and the electrode. Heat from the arc melts the electrode and the metal being welded allowing them to be joined into a solid piece. The molten weld puddle is protected from the atmosphere by a “gaseous envelope” that is created when the electrode coating is vaporized by the heat of the arc.

SMAW Equipment Requirements: Constant current power source (AC, DC or AC/DC). Welding cables with electrode holder and ground clamp. Electrodes

Advantages of the SMAW Process: Cheapest common arc welding equipment to purchase. Used to weld ferrous and non-ferrous metal. All position welding. Ideally suited for outdoor work. Highly portable. Consumables and equipment readily available.

Disadvantages of the SMAW Process Low productivity, especially when compared to the GMAW process. High amount of electrode loss. Dirtiest of the common arc welding processes. Requires much post weld clean-up. Can be difficult to master.

SMAW Variables: In order to create consistent, quality welds using the SMAW process, the operator must know and control the following welding variables: Welder polarity setting. (based on electrode type and material thickness). Initial amperage setting (based on electrode size and type).

SMAW Variables: Electrode angle: 10 to 20 degrees in the trailing or drag direction. Arc length: One electrode diameter Travel speed: Finished beads should be three electrode diameter in width. Electrode manipulation (if needed)

Troubleshooting Quality Issues in SMAW Welds: Excessive weld bead width; reduce amperage setting and/or increase travel speed. Excessive weld bead convexity (convex-too much curve); increase amperage setting. Lack of weld puddle control; reduce amperage setting and/or reduce arc length. Lack of bead width: increase amperage setting and/or reduce travel speed.