Shielded Metal Arc Welding

Shielded Metal Arc Welding

• Shielded Metal Arc Welding (SMAW) welding:– The oldest of the arc welding processes.– Uses a filler rod coated with flux. (electrode)

• SMAW welding is a versatile process: – It can be performed with basic equipment.– It may be used in most conditions. – SMAW can weld aluminum, but not very well.

How it Works

• An arc is struck between the rod and the work piece:– The arc causes the filler rod and flux to melt.

• Melting flux creates a gas shield to prevent oxidation.

• The flux forms a hard slag over theweld to prevent oxidation during cooling. – When welding is complete this slag is chipped

off.

Welding Circuit

Welder

Electrode Cable

Electrode Holder

Work PieceWork Cable

Arc

Electrode

Welding Circuit

Electrical current travels through the welding circuit. Where it “jumps” between the electrode and the work piece creates the arc.

Welding Current

Welding Set-Up

Work Cable

Weld Bead

Work Piece

Electrode Holder

Electrode

Work Clamp

Arc Length

The Arc

Work Piece

Hazards of Arc Welding

• Fume Inhalation• Electric Shock• Fire• Welder’s Flash or Arc Eye• Burns

Fume Inhalation

• Welding gives off a variety of particle fumes and gases.

• Most fumes and gases are harmful.• It is essential that operators protect

themselves. • Fume extraction removes fumes at the

source.

Fire

• Spatter and sparks from welding can set fire to materials around the work station.

• Always work in a clean well organized area.

Electric Shock

• Never use arc welding equipment in damp conditions.

• Always ensure the equipment is in good condition.

• Keep yourself insulated from the work piece.

Welder’s Flash / Arc Eye

• This condition is caused when the Ultra Violet radiation that arc welding processes emit burns the retina of the eye.

• Arc-eye is extremely painful and can lead to permanent blindness.

• Always wear eye protection when welding. It is the welder’s responsibility to protect others.

Burns

• Ultra Violet radiation can also burn skin.• This happens in exactly the same way as

a sunburn, only much quicker. • Like sunburn, long term implications can

include skin cancer.• It is essential that suitable work wear is

worn and that others are protected.

Safety Equipment

• Long sleeves• Long pants• Welding helmet with shade 9-12 lens• Pliers for handling hot metals• Dry Leather Gloves• Safety glasses under welding helmets