Techniques and Tips for SMAW Operation

SMAW Operation Set-up

Before starting make sure that you are using a helmet for SMAW welding as well as protective clothing.

Operation

Starting the Arc

Scratch Start Technique:

To strike the
electric arc when starting a SMAW operation, the electrode is brought into contact with the workpiece,
dragged like lighting a match, and then pulled away slightly.If the arc
lights and then goes out, that means the electrode was pulled too far
away from the base metal. If the electrode sticks to the metal, give a
twist and it should come free.

Tapping Technique:

Move
the electrode straight down to the base metal. Then lift slightly. The
arc should start. If the arc goes out, that means it was lifted too high
off the workpiece.

Operating the Electrode Holder

This initiates the melting of the workpiece and the
consumable electrode, and causes droplets of the electrode to be passed
from the electrode to the weld pool.

As the electrode melts, the flux covering disintegrates, giving
off a vapors that protect the weld area from oxygen and other
atmospheric gases.

In addition, the flux provides molten slag which covers the filler metal as it is travels from the electrode to the weld pool.

Once part of the weld pool, the slag floats to the surface and protects the weld from contamination as it solidifies.

 

Groove (Butt) Joint Welding

Tack Welds

Tack weld the two pieces of metal to hold them in place. This will reduce joint distortion, which is caused by the expansion and contraction of metal as it is heated and cooled.

Double V-Groove, Single V-Groove and Square Groove Welds

When performing a groove weld, hold the electrode perpendicular to the weld. Lean the electrode in the direction of the weld.

A
single string bead is all that is needed for a narrow groove weld
joint. For wider groove weld, then a weave bead or many stringer beads
is a better option.

Square Groove Weld

If thickness of materials are 3/16" (5MM) they can usually be welded with a square groove weld and no prep.

 

V-Groove

For SMAW operation welds that require thicker metals it may require that edges are prepared (v-groove) of butt joints for good welds.

V-groove
is recommended for metal thickness of 3/16" to 3/4" (5 to 19mm). It is
also used for any thickness when welding can only be done from one side.

The bevel can be created (at 30 degrees) using a grinder, or
plasma or oxyacetylene cutting equipment. After creating the bevel
remove scale.

T-Joint Welding

Fillet Weld

For a fillet
weld, hold the electrode at a 45 degree angle or less to the weld. Lean the
electrode 10 degrees to 30 degrees in the direction of the weld.

Use a short arc and move at a steady speed. For upright sections weld both sides.

When necessary for strength add a second layer (remove slag before adding another layer).

Move the electrode using a circular motion.

Lap Joints

When welding a lap joint the electrode should be held at a 30 degree angle or less. Use one or two weld passes as needed. Before the second pass remove any slag.

Welding Positions

Each welding position is described below. Note that not every electrode is right for each position. Check the manufacturers directions before proceeding with any SMAW operation.

Horizontal

The issue with the horizontal welding is the distorting effect gravity will have on the  weld pool. If necessary or if it will help, tack weld a backing strip. Beveled edges can also be of help.

When welding during the SMAW operation keep the electrode at 90 degrees to the weld. Lean into the weld direction by 15 degrees.

Vertical Welding Position

The weld direction can move from top to bottom or bottom to top. It is easier to weld in an upward direction.

Use a tack welded backing plate if needed and for thicker materials bevel the edges.

Hold the electrode at 90 degrees to the material being welding.

Overhead Welding Position

For an overhead weld the arc should be positioned slightly away an dout from the crater. Tack weld a backing plate and use beveled edges if necessary.

Testing the Weld

Use a hammer to strike the joint on the material welded to the base. The weld should bend slightly and not break. Breakage could be due to too many holes (porous) in the weld, or if the weld contains slag. Also note if any of the beveled area is visible. If it is, this could indicate that the filler material was not fully melted due to traveling too fast with the electrode or by not using enough heat.

Slag Removal

Once hardened, it must be chipped away to reveal the
finished weld. As welding progresses and the electrode melts, the welder
must periodically stop welding to remove the remaining electrode stub
and insert a new electrode into the electrode holder.

This activity, combined with chipping away the slag,
reduce the amount of time that the welder can spend laying the weld,
making SMAW one of the least efficient welding processes.

For Additional Reading

 

 

 

Page Author: Jeff Grill