Transcript Document

Work to be welded is connected to one side of an electric circuit (the
ground cable). A metal electrode is connected to the other side (the
electrode cable). These two parts of the circuit are brought together and
then separated slightly.
The electric current jumps the gap and causes a continuous spark called
an arc. The high temperature of this arc melts the metal to be welded,
forming a molten puddle.
The electrode also melts and adds metal to the puddle. As the arc is
moved, the metal solidifies.
**The melting action is controlled by changing the 1) amount of electric
current that flows across the arc and 2) the size of the electrode. **
Alternating Current: reverses direction 120 times per second
Direct Current: flows in same direction at all times
*We will always use DC+ current.*
DC+ sets the metal piece is negative; electrode is positive.
DC+ is more stable and every electrode can be used!
-Usually has a steel core, which is covered with a coating that shields the
arc to keep harmful oxygen and nitrogen in the atmosphere away from
the weld.
(American Welding Society)
1= all positions (2= flat/horizontal;3=deep groove)
3= indicates operating characteristics
(polarity,coating, etc.)
60 = gives minimum tensile strength in thousands psi (60,000)
Right-handed welders see better welding L to R; while left-handed
welders should weld R to L.
4 Things that Affect the Results of Arc Welding:
1.) current setting (or amperage)
2.) length of arc (or arc voltage)
3.) rate of travel
4.) angle of electrode
*General rule of thumb: current setting (amps) should be equal to the
diameter of the electrode (core rod) in thousandths of an inch
1/8” electrode =.125” and operates well at 125 +/- 10 (115-135)
5/32”electrode =.156” and operates well at 150+/-10 (140-160)
*Arc length increases as arc voltages increases.*
Ex: arc 3/16” long requires 3x the voltage of a 1/16” arc
*Arc length should be slightly less than diameter of electrode being
*Use the sound of the arc to guide you: sound should be sharp, energetic
*Electrode must be fed downward at a constant rate to keep the right arc
*Rate of travel of the arc changes with the thickness of the metal being
welded, amount of current, and shape/size of weld (bead) wanted.*
*Arc length and arc travel should be such that the puddle of molten metal
is about twice the diameter of the rod used.*
On flat pieces, electrode should make an angle of 90 degrees with
the work. In other than flat work, good results are obtained if the
rod splits whatever angle is being welded.
(Ex: 90 degree angle weld; electrode should be tilted at a
45 degree angle for best results.)