Stick Welding (SMAW) Fundamentals

In stick welding, formally shielded metal arc welding (SMAW), a coated electrode carries the current and melts into the joint. The flux coating burns to make shielding gas and leaves a slag blanket over the weld. You need no gas cylinder and no wire feeder, so the process works on a job site, in wind and on steel that is not perfectly clean. It also demands more hand skill than wire welding, because the rod gets shorter as you weld and your hand has to keep following it.

What You Will Be Able to Do

• Read an electrode classification, and choose a rod.
• Set polarity and a starting amperage.
• Hold the right arc length, work angle and travel angle.
• Choose a stringer or a weave, and weld out of position.
• Fix sticking, porosity, arc blow and other stick problems.

How the Process Works

The electrode is a metal core wire with a flux coating. When you strike an arc, the coating does these jobs:

• It burns to form gas that shields the molten metal from air.
• It forms slag, which protects the cooling weld and shapes the bead.
• It adds alloys and stabilizes the arc.

Because the shielding comes from the rod, wind does not blow it away the way it does with MIG or TIG gas. That is the main reason stick stays the go-to process outdoors. It also tolerates some rust and scale, though cleaner metal always gives a better weld. Stick machines are constant-current (CC) power sources.

Reading the Electrode Number

Take E7018:

The first two digits, or three on higher-strength rods, give the strength in thousands of psi. So E6010 is 60,000 psi and E7018 is 70,000 psi. On a longer number such as E11018, the second-to-last digit is still the position digit, so read it from the end.

E6010 has a cellulose coating and a fast-freezing, digging arc that cuts through rust and scale. Pipeline crews use it for root passes.

E6011 does the same job on AC. If your only machine is an AC transformer buzz box, you cannot run E6010, so substitute E6011.

E6013 is smooth and easy. Its shallow penetration and non-low-hydrogen coating make it fine for sheet metal and farm repairs, but it is generally not acceptable for code structural work.

E7018 is a low-hydrogen rod, the standard for structural and code work. Its coating has very little moisture, which helps prevent hydrogen cracking, as long as it stays dry.

Polarity

Rod makers print the allowed current on the box. Match it. Wrong polarity is a very common beginner mistake, and it shows up as a harsh, spattery arc.

Setting Amperage

A rough rule says 1 amp for each 0.001 inch of core wire diameter. A 1/8 inch rod is 0.125 inch, so around 125 amps. Then fine-tune by what the puddle does.

For 1/8 inch E7018 in the flat position on 3/16 inch steel, 115 to 130 amps is a reasonable start. Drop 10 to 15 percent for vertical and overhead. These numbers are starting points. The rod maker's data and your WPS, if you have one, come first.

Striking and Holding the Arc

1. Clamp the work lead to clean, bare metal near the weld.
2. Grip the bare end of the rod in the stinger, the electrode holder. Keep your gloves dry.
3. Lower your hood.
4. Strike by scratching the rod like a match, or tap and lift. Start in the joint, so you do not leave arc strikes on the base metal.
5. Hold the arc length at about the diameter of the core wire. A 1/8 inch rod runs about a 1/8 inch arc.
6. Feed the rod down steadily as it burns, and move along the joint.

If the arc is too long, you get spatter, porosity and undercut. If it is too short, the rod sticks. Low-hydrogen rods need an especially short arc.

Warning: The rod is live as long as it is in the stinger and the machine is on. Remove the stub and hang up the stinger before you put it down. Never change rods with bare hands or wet gloves.

Angles

Work angle is the rod's angle from the joint, viewed from the end of the weld. On a tee joint fillet, 45 degrees splits the heat between both plates. On a flat groove or butt joint, it is 90 degrees.

Travel angle is the tilt along the line of travel. Stick uses a drag angle: tilt the rod 5 to 15 degrees, with the top leaning toward the direction you are going so that the tip points back at the finished weld. For E7018, about 10 to 15 degrees is typical. If you push instead, slag runs ahead of the arc and gets trapped.

Travel Speed and Bead Shape

Watch the back edge of the puddle, and keep the slag behind you. A good flat bead is about 2 to 3 times the rod diameter wide, and slightly crowned.

• Too slow: The bead piles up tall and overbuilt, with heavy slag that can roll ahead of the arc.
• Too fast: The bead is thin and undersized, with undercut.

Stringer and Weave Beads

Keep weaves narrow. Many procedures limit weave width to about 2.5 times the rod core diameter, and your WPS is the rule. Wide weaves trap slag and add heat.

E6010 runs differently from E7018. A common E6010 technique is a whip and pause: flick the arc forward, then bring it back to the puddle to let it freeze. E7018 wants a short, steady arc with no whip.

Welding Out of Position

• Vertical up: Run 10 to 15 percent fewer amps than flat. For E7018 on a vertical fillet, weld uphill, with a slight side-to-side motion and a pause at each toe. Code structural work is normally vertical up.
• Vertical down: It is faster and shallower. It is used on thin steel and for some pipeline passes with E6010. Only use it if the procedure allows it.
• Overhead: Use stringers, a very short arc and lower heat, and wear full leathers.

Cleaning Between Passes

1. Let the slag cool until it stops glowing.
2. Chip it off, working along the bead. Wear safety glasses, because slag flies.
3. Wire brush the bead.
4. Look for pores, undercut and trapped slag.
5. Grind out any flaws, and grind down ropy spots where slag can hide.

Never weld over slag. It will not reliably burn out.

Storing Low-Hydrogen Rods

Keep opened E7018 in a heated rod oven at about 250 to 300 F. Exposed rods absorb moisture, and moisture adds hydrogen. Wet rods cause porosity and can cause hydrogen cracks. If a can is left open on a truck overnight and you have no oven, the rods must be rebaked as the maker or code requires, typically 500 to 800 F for one to two hours, or thrown away. Do not use them as they are. E6010 is different: its coating needs some moisture, so never put it in a hot rod oven.

Troubleshooting

Arc blow happens when magnetic fields around the work push the arc off course on DC, especially near the ends of a plate or in corners. Move the work clamp closer to the weld, change the direction of travel, or switch to AC if the rod allows it.

If the rod freezes to the plate, twist it off by bending it back and forth. If it will not come free, release the rod from the stinger.

Common Mistakes

• Running E6010 on an AC machine. It will not hold an arc. Use E6011.
• Holding a long arc with E7018. You get porosity at the start and all along the bead.
• Welding over slag. You leave inclusions.
• Setting rods down hot and live. Hang up the stinger.
• Using wet E7018. Moisture can crack the weld later.

Check Your Understanding

You need to weld a rusty gate outside with an AC buzz box. Which rod do you choose, and why?

E6011. It has a digging arc for dirty steel, and it runs on AC, unlike E6010.

Your arc keeps pulling to one side at the end of a plate, even though the steel is clean. What is happening, and what can you do?

That is arc blow. Move the work clamp closer to the weld or change your direction of travel. If the rod allows it, switch to AC.

A 1/8 inch E7018 keeps sticking to the plate on 3/16 inch steel at 95 amps. What should you try first?

Raise the amps toward the 115 to 130 range, and lift the arc slightly.

Your foreman says you can run E6013 on a structural joint because it is easier. What is the problem?

E6013 has shallow penetration and is not a low-hydrogen rod, so it is generally not acceptable on code structural work. Check the WPS.

Key Takeaways

• The flux coating makes gas and slag, so stick works well in wind and on field work.
• In E7018, 70 means 70,000 psi, the 1 means all positions, and the coating is low hydrogen.
• E6010 and E7018 run DCEP. E6011 is the AC substitute for E6010.
• Hold an arc about as long as the core wire is wide, and drag the rod.
• Use stringers on roots and out of position. Keep weaves narrow.
• Clean every pass, and keep low-hydrogen rods dry in an oven.