Besides the steady sizzling sound that a correct arc produces, the shape of the molten pool and the movement of the metal at the rear of the pool serve as a guide in checking weld quality.  In a correctly made deposit, the ripples produced on the bead will be uniform and the bead will be smooth, with no overlap or undercut.

CORRECT ELECTRODE SIZE

The correct choice of electrode size involves consideration of a variety of factors, such as the type, position, and preparation of the joint, the ability of the electrode to carry high current values without injury to the weld metal or loss of deposition efficiency, the mass of work metal and its ability to maintain its original properties after welding, the characteristics of the assembly with reference to effect of stresses set up by heat application, the practicability of heat treatment before and/or after welding, the specific requirements as to welding quality and the cost of achieving the desired results.

CORRECT CURRENT

If current on equipment is too high or too low, you are certain to be disappointed in your weld.  If too high, the electrode melts too fast and the molten pool is large and irregular.  If too low, there is not enough heat to melt the base metal and the molten pool will be too small, will pile up and look irregular.

CORRECT ARC LENGTH

If the arc is too long or voltage too high, the metal melts off the electrode in large globules which wobble from side to side as the arc wavers giving a wide, spattered and irregular bead – with poor fusion between original metal and deposited metal.  If the arc is too short, or voltage too low, there is not enough heat to melt the base metal properly and the electrode quite often sticks to the work, giving a high, uneven bead, having irregular ripples with poor fusion.

CORRECT TRAVEL SPEED

When the travel speed is too fast, the pool does not last long enough and impurities and gas are locked in.  The bead is narrow and ripples are pointed.  When the travel speed is too slow, the metal piles up and the bead is high and wide with a rather straight ripple.

CORRECT ELECTRODE ANGLE

The electrode angle is of particular importance in fillet welding and deep groove welding.  Generally speaking, when making a fillet weld, the electrode should be held so that it bisects the angle between the plates and is perpendicular to the line of weld.  If undercut occurs in the vertical member, lower the angle of the arc and direct the arc toward the vertical member.

Pocket Welding Guide, 27^th edition. Hobart Institute of Welding Technology.  To order a copy of this book, contact the Training Materials Dept. at 1-800-332-9448, ext. 5433 or order online at http://www.welding.org