Shielded Metal Arc Welding

Shielded Metal Arc Welding

Arc Welding?•Uses electricity for heat

Arc Welding ?•Electrodes (Rods) covered with flux

Arc Welding?•Gas cloud (Shield) around the metal during welding

Arc Welding•Heat for arc welding comes from electricity

•Welder = machine used for welding that produces a current

Arc Welding

•Arc = discharge of electricity

•Weldor = a person who welds

Arc Welding

•Electrodes = flux coated metal rods

Arc Welding

Arc Welding•Electrode Holder = spring loaded device with insulated handles used to grip the electrode

•Ground Clamp = spring loaded clamp that is attached to an electrical cable

Arc Welding

•Chipping Hammer = steel hammer with a sharp edge/point and a wire brush

Arc Welding

Arc Welding•Helmets = cover your head and neck region-- a # 10 shield is required

•Safety Glasses = must be worn under the welding helmet

Arc Welding

•Welding Gloves = insulated gloves worn to protect hands from heat and sparks (not 100%)

Arc Welding

Welding Process

W = Watts = measure of energy available

W = V X A

V = Voltage = measure of electrical pressure

W = V X A

A = Amp = rate of flow of current

W = V X A

Temperature

•Arc can be up to 9000 degrees F.

Temperature• Depends on:

–Arc Length–Electrode type–Amp Setting–Base Metal

Duty Cycle

•The percentage of time that a welder can operate without overheating

•The number of minutes out of 60 that a welder can operate at full capacity

Duty Cycle•The number of minutes out of 60 that a welder can operate at full capacity

AC/DC•AC

–Alternating Current

–Rev. Direction

AC/DC•AC

-U.S. 60 Cycles per second

AC/DC•AC

–Use Transformers to step-down voltage and increase amps

AC/DC•DC

–Direct Current–Electricity flows in one direction

AC/DC•DC

–Straight vs. Reverse Polarity

–Use Generators to produce the DC

Electrode Coding NEMA

•Uses color coding on the rods

• 3 areas on the rod

Electrode Coding AWS

•# coding system on the rods

•Each # stands for something

E6013•E = Electrode

•60 = Tensile Strength

•1 = Welding Position

•3 = Welding Current

Flux

•Shields Outside gasses

Flux

•Combines with metal impurities

Flux•Forms Slag

•Makes and Maintains Arc

What Affects a Weld Bead???

•Temp of Base Metal

–Adjust your Amps

What Affects a Weld Bead???

•Electrode Diameter and Flux Type

What Affects a Weld Bead???

•Amps–Select according to the thickness of your metal

What Affects a Weld Bead???

•Arc Length

–“Frying Bacon”

What Affects a Weld Bead???

•Electrode Angle

–10 to 15 degrees from vertical

What Affects a Weld Bead???

•Speed of Travel

–Even across the metal

Arc Welding Safety•Weld on a proper surface

•Fire Exting./blanket nearby

Arc Welding Safety•Surrounding area???

•Wear all safety equipment/gear