FACTS ABOUT SMAW Originated at start of WWI for shipbuilding SMAW is the least expensive arc welding processes Is the most widely used welding process in the world Can be used to weld most common metals and alloys
6 1- The Electrode Consumable… 2 Part Composition Core Rod (Metal Filler) Carries welding current & Becomes part of the weld Flux Coating Produces a shielding gas & helps form slag
7 2- The Arc Turn on the light…An arc occurs when the electrode comes in contact with the work-piece and completes the circuit The electric arc is established in the space between the end of the electrode and the work causing resistance The arc reaches temperatures of 10,000°F which melts the electrode and base material Can you identify the weld joint and position being used?
8 3- Weld Puddle As the core rod, flux coating, and work pieces heat up and melt, they form a pool of molten material called a weld puddle The weld puddle is what a welder watches and manipulates while welding 1/8” E6013 at 125 Amps AC
9 4- Shielding Gas A shielding gas is formed when the flux melts. This protects the weld puddle from the atmosphere preventing contamination during the molten state The shielding gas protects the molten puddle from the atmosphere while stabilizing the arc 2 3 Shielding Gas 4
10 5- Solidified Weld Metal As the molten weld puddle solidifies, it forms a joint or connection between two pieces of base material When done properly on steel, it results in a weld stronger than the surrounding base metal Bead width = 2.5 to 3 times electrode diameter 3/8 ”
11 6- Slag Combination of melted flux & base metal impurities Quickly solidifies to form a shell Slows the cooling rate of weld Chip and clean with hammer & brush If proper technique is used it should come off easy Never weld over slag!! ALWAYS SIDE CHIP SLAG, DON’T HIT IT LIKE A HAMMER
Slag You Drag! Slag Welding Processes – ALWAYS PULL THE PUDDLE – Shielded Metal Arc Welding (SMAW) – Flux Core Arc Welding (FCAW) No-Slag Welding Processes – ALWAYS PUSH THE PUDDLE – Gas Metal Arc Welding (GMAW) – Gas Tungsten Arc Welding (GTAW) – Oxy-Fuel Welding
13 SMAW Process 1 Travel direction Electrode Arc 2 Weld Puddle 3 Shielding Gas 4 Solidified Weld Metal 5 Slag 6 1 Travel direction Electrode Arc 2 Weld Puddle 3 Shielding Gas 4 Solidified Weld Metal 5 Slag 6
Electrode Selection What type of welder do I have, AC or DC? What am I welding, steel, cast, stainless, etc? What is the metal condition, dirty or clean? Is it a root or cover pass? How strong does it have to be? What electrodes do I have to chose from?
Amperage Chart Amperage is dependent on electrode diameter, electrode type, and metal thickness Reference charts whenever possible.
Amperage Electrode Shorthand method will get you in the ballpark for fast freeze electrodes. Not 100% accurate for all electrodes! AWS: 1/8” diameter E6013 1/8”=.125” 125 Amps
Electrode Care Electrodes must be kept dry – Dampness will introduce hydrogen into the weld causing cracking or brittleness – Damp electrodes may cause the flux to “blow away” & cause porosity – Bake questionable electrodes for several hours. – 6010 & 6011 (fast freeze) are exempt Our electrodes are stored in a dry oven
Electrodes Care cont. Burn electrodes down to numbers! Place stubs in stub box Put unused electrodes back in oven Only grab several electrodes at a time Electrodes are not cheap
22 Striking an Arc and Making a Weld
23 Striking an Arc To begin the SMAW Process, you must first strike an arc. – Scratch start – scratch the electrode on the base metal like a match – Tap Start – tap the rod against the base metal
24 Work Angle The work angle is the angle between the electrode and the work as depicted on the left Work angles can vary depending on the position the weld is being made in 90°
25 Travel Angle Also commonly called Lead Angle The travel (lead) angle is the angle between the electrode and the plane perpendicular to the weld axis 20-30°
26 Arc Length After striking the arc, maintain a 1/8” distance between the electrode and the workpiece – Too short: electrode will fuse itself to metal – Too long: spatter, undercut, and porosity Arc Length = 1/8”
27 Travel Speed Speed at which the electrode moves along the base material while welding – Too fast: ropey or convex weld – Too slow: wide weld, excessive deposit The travel speed impacts the shape of the bead.
28 Filling the Crater At the end of the weld, the operator breaks the arc which creates a ‘crater’ Use a short pause or slight back step at the end of the weld to fill the crater Large craters can cause weld cracking Back stepping is a short move in the opposite direction of weld travel
29 Restarting a Bead Remove electrode from stinger Scratch electrode until metal can be seen Scratch in weld line: spatter 1. Strike Arc Here 2. Move Electrode to Crown of Crater 3. Resume Travel
30 Troubleshooting Activity AB C DE FG On a piece of scratch paper, describe welds A-G. Good, bad, arc length, speed, lead angle, etc.
A – Good Weld: Proper Current, Speed and Arc Length B – Current low: Ropey, convex bead appearance C – Current too High: Excess spatter & burn-through D – Arc Length too short: Poor wet-in at toes E – Arc Length too Long: Spatter, undercut and porosity F – Travel Speed too slow: Wide weld with excess deposit G – Travel Speed too high: Ropey and convex bead
Lincoln V350 SMAW Setup 1.Plug ground cable into the (-) terminal 2.Plug the whip cable into the (+) terminal 3.Turn on the welder 4.Select SMAW (CC-Stick Soft) mode – CC-Stick Crisp is for pipe welding 5.Select correct amps 6.Set Hot start to 2-3 – (This will make starting the arc easier) 7.Set Arc Control to +4-5 – (high arc control = crisp weld but more spatter) – (low arc control = soft weld with little spatter)