SMAW - Shielded Metal Arc Welding Definition – Producing an arc between base metal and a consumable, flux covered metal electrode. The electrode acts as an electrical conductor and a filler metal.

SMAW Advantages Equipment less complex, more portable and less costly Can be done indoors or outdoors, in any location and any position Electrodes available to match properties and strength of most base metals Not used for welding softer metals Not as efficient in deposition

Requirements to Arc Welding Power Source – Either AC or DC Electrode Holder (Stinger) and Cable Work Clamp and Cable Electrode Base Metal

SMAW Operating Principles Sets up electric circuit Includes welding machine, work, electric cables, electrode holder and electrodes, and a work clamp Heat of electric arc brings work to be welded and consumable electrode to molten state Heat intense: as high at 9,000ºF at center

Starting, Stopping and Adjusting Never start the machines under a load On/Off Switch Amperage (current) set up by control knob – can be adjusted while welding Voltage – controlled by the length of the arc gap - small arc gap = less voltage (cold) - large arc gap = more voltage (hot)

Electrodes First Letter – “E” is Electric Arc Welding “ER” is used for Gas Welding First 2 or 3 digits provide the tensile strength in thousands of lbs / in squared 2nd digit from the right – recommended position 1 – All Positions 2 – Flat or Horizontal 4 – Flat, Horizontal, overhead, and downhill welding

Electrodes Cont… Last two numbers together represent proper application and covering composition EXX11 – High – cellulose, potassium EXX13 – High-titania, potassium EXX18 – Iron Powder, Low-hydrogen, potassium 0,1 Fast Freeze Rod 2-9 Filler Rod

Electrodes Cont… As the Electrode melts it accomplishes two tasks Provides Filler Material - Deposition – How much metal is deposited in the weld. Flux – Creates a gas that shields the weld and lays down “slag” to allow the weld to cool slowly and remain pure

Striking an Arc Electrode must first strike the base metal then be withdrawn to the correct arc distance or length. Stabilizing the Arc When first starting the Electrode might stick This is because the arc length is too small When welding with thin metal – lift the electrode and base metal off of the table When welding thicker (heavier) metal – release the electrode from the stinger When the arc length is too great the arc will go out

Striking an Arc Cont… In order to produce a weld you need to be able to stabilize the arc and create a pool Scratching Method Bump Method

Running a Bead After establishing a stable arc we are ready to create a weld bead To “run” a good bead requires 4 things Arc Gap distance or Arc Length Speed of Travel Correct Amperage Electrode Angle – 15 to 20 degrees in direction of travel

Arc Welding Joints Butt Lapp Corner T-Joint Edge

AC Versus DC Power Direct Current

AC Versus DC Power NO Current

AC Versus DC Power Alternating Current

Safety Hazards Radiation from the arc: Ultraviolet and Infrared rays Flying Sparks and molten globules Electric Shock Fumes Burns

Safety Cont… Never look at an arc from any distance unless your eyes are protected Welding Helmets – shade 10 lens Protects more than just your eyes! Face, hands, arms, and other skin surfaces must be protected – burns are comparable to sun burns

Safety Cont… Flammable Materials Avoid welding in wet or damp areas Always weld in areas that are well ventilated

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Procedures Make sure you have all safety materials – gloves, clothing, safety glasses, welding helmets Electrode Check-out procedures Partners Metal

Procedures Cont… Use pliers or tongs to handle hot metal When leaving hot metal lying around please mark on it with a piece of soapstone – HOT Don’t ever under any circumstances hand me a piece of hot metal!! Use the tanks outside to cool off metal