GAS META

L ARC

WELD

ING

DEFINITION

Intense heat of an electric arc is used to melt filler material and base metal while a wire electrode is continuously fed into the arc. A shielding gas protects the weld from contamination.

EQUIPMENT

1. Direct Current

2. Constant Voltage Power Source

3. Wire Feeder w/control system

4. Electrode wire

5. Welding gun

6. Electrical Cable

7. Shielding Gas

TYPES OF METAL TRANSFER

• Short Circuit- molten metal is deposited in repeated short circuits

• Globular- molten metal is transferred across arc in large droplets

• Spray- molten metal is propelled axially across the arc in small droplets

ADVANTAGES

1. High Deposition Rates

2. High Utilization of Filler Material

3. Elimination of Flux/Slag Removal

4. Reduction of Smoke & Fumes

5. Can be Automated

6. Less Skill Required

DISADVANTAGES

1. Cost

2. Metal preparation time

3. Unsuitable for outdoor welding

4. Fast cooling rates

5. Unsuitable for thick metals

6. Shielding gas required

INTERNAL DIAGRAM OF WIRE FEED SYSTEM

TIP DISTANCE DIAGRAM

WELDING TERMINOLOGY

ARC WELDING

Type of welding when weld is produced by heating metal with an arc with or without the use of filler material or pressure

ELECTRODE

A component of the welding circuit through which current is conducted to the arc, molten, slag or base metal

FLUX

Material used to prevent, dissolve or remove oxides and other undesirable materials from a weld

BASE METAL

The metal to be welded, soldered or cut

POROSITY

Cavity formed by gas entrapment during solidification

SPLATTER

Metal particles expelled during welding that does not form as part of the weld

TACK WELD

Weld made to hold part of the weldment in proper alignment until the final welds are made

INERT GAS

A gas that goes not normally combine chemically with the base metal or filler metal. Creates a protective atmosphere.

UNDERCUT

A groove melted into the base metal adjacent to the toe or root of a weld and left unfilled by weld metal

WELD

A localized joining of metal produced by heat

FILLER METAL

The metal to be added in making a welded joint.

READING ELECTRODES

ER-70S-6E=ElectrodeR=Filler Metal Rod70= Tensile Strength

ER-70S-6S= Solid Wire6=Chemical Composition of

the Wire

PRACTICE READING ELECTRODES

WELD ANATOMY