© COPYRIGHT 1998 THE ESAB GROUP, INC. LESSON II Other functions of the coating are to provide arc stability and control bead shape.  More information on coating functions will be covered in subsequent lessons. * Shielded Metal Arc Welding (SMAW) is the terminology approved by the American Welding Society. 2.2.1 Equipment & Operation - One reason for the wide acceptance of the SMAW process is the simplicity of the necessary equipment. The equipment consists of the following items.  (See Figure 2) 1. Welding power source 2. Electrode holder 3. Ground clamp 4. Welding cables and connectors 5. Accessory equipment (chipping hammer, wire brush) 6. Protective equipment (helmet, gloves, etc.) 2.2.2 Welding Power Sources - Shielded metal arc welding may utilize either alternating current (AC) or direct current (DC), but in either case, the power source selected must be of the constant current type.  This type of power source will deliver a relatively constant amperage or welding current regardless of arc length variations by the operator (See Lesson I, Section 1.9).  The amperage determines the amount of heat at the arc and since it will remain relatively constant, the weld beads produced will be uniform in size and shape. Whether to use an AC, DC, or AC/DC power source depends on the type of welding to be done and the electrodes used.  The following factors should be considered: 1.   Electrode Selection - Using a DC power source allows the use of a greater range of electrode types.  While most of the electrodes are designed to be used on AC or DC, some will work properly only on DC. 2.   Metal Thickness - DC power sources may be used for welding both heavy sections and light gauge work.  Sheet metal is more easily welded with DC because it is easier to strike and maintain the DC arc at low currents. FIGURE 1 COATING CORE ROD SHIELDING GASES SOLIDIFIED SLAG WELD METAL WORK PIECE MOLTEN POOL SHIELDED METAL ARC WELDING AC OR DC POWER SOURCE ELECTRODE CABLE ELECTRODE HOLDER ELECTRODE GROUND CABLE WORK SHIELDED METAL ARC WELDING CIRCUIT FIGURE 2

Lesson 1
The Basics of Arc Welding
Lesson 2
Common Electric
Arc Welding Processes
Lesson 3
Covered Electrodes for Welding
Mild Steels
Lesson 4
Covered Electrodes for Welding Low Alloy Steels
Lesson 5
Welding Filler Metals for Stainless Steels
Lesson 6
Carbon & Low Alloy
Steel Filler Metals -
Lesson 7
Flux Cored Arc Electrodes Carbon Low Alloy Steels
Lesson 8
Hardsurfacing Electrodes
Lesson 9
Estimating & Comparing Weld Metal Costs
Lesson 10
Reliability of Welding Filler Metals
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