Essentials for proper welding Causes and cures of common welding troubles


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Essentials for proper welding procedures
Correct electrode size
Correct current
Correct arc length or voltage 4 Correct travel speed
Correct electrode angle

Besides the steady sizzling sound that correct arc procedures, 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 over lap or under cut.

Correct electrode size
The correct choice of electrodes size involves consideration of a variety of factors, such as the type , position , and preparation of the joint , the ability of the electrodes 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 specific requirements as welding quality and cost of achieving the desired results.

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

Correct arc length
If the arc is total 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 regular bead with poor fusion arc is too short, or voltage too low, there is not enough heat to melt the base metal property and the electrode quite sticks to the work, giving a high, uneven bead, having irregular rippled with fusion.

Correct Travel speed
When your speed is too fast your pool does not last long enough, impurities and gas are locked in. The bead is narrow and ripples are pointed. When speed is too slow the metal piles up, the bead is high and wide, with a reference 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 (as shown at right ) and is perpendicular to the line of weld. If under cut occurs in the vertical member, lower the angle of the arc and direct the arc towards the vertical member.

Causes and cures of common welding troubles

Porous welds why
  • Excessively long or short arc length
  • Welding current too high
  • Insufficient or damp shielding gas
  • Too fast travel speed
  • Base metal surface covered with oil grease, moisture, rust, mill scale, etc
  • Wet unclean or damage electrode
What to do
  • Maintain proper arc length
  • Use proper welding current
  • Increase gas flow rate & check gas purity
  • Properly maintain and store electrodes 5.Reduce travel speed
Cracked welds Why
  • Insufficient weld size
  • Excessive joint restraint
  • Poor joint design and/or preparation
  • Filler metal does not match base metal
  • rapid cooling rate
  • Base metal surface covered with oil grease, moisture, rust, dirt or mill scale
  • Adjust weld size to part thickness
  • Reduce joint restraint through proper design
  • Select the proper joint design
  • use more ductile filler
  • Reduce cooling rate through preheat
  • Properly clean base metal prior to welding
Undercutting why
  • Faculty electrode manipulation
  • Welding current too high
  • Too long an arc length
  • Too fast travel speed
  • Arc blow
What to do
  • Pause of side of the bead when using a weaving technique
  • Use proper electrode angles
  • Use proper welding current for electrodes size]
  • Reduce arc length
  • reduce travel speed
  • reduce effects of arc blow
Distortion why
  • Improper tack welding and /or faulty
  • Improper bead sequence
  • Improper set up and fixturing
  • Excessive weld size
What to do
  • Tack weld parts with allowance for distortion
  • Use of bead sequencing
  • Tack or clamp parts securely
  • Make welds to specified size
Spatter why
  • Arc below
  • Welding current too high
  • Too long an arc length
  • Wet unclean or damaged electrode
What to do
  • Attempt to reduce the affect of arc below
  • Reduce welding current
  • Reduce arc length
  • Properly maintain and store electrodes
Lack of fusion why
  • Improper travel speed
  • Welding current too low
  • Faulty joint preparation
  • Too large an electrode diameter
  • Magnetic arc below
  • Wrong electrode angle
Overlapping why
  • Too slow travel speed.
  • Incorrect electrode angle.
  • Too large an electrode.
What to do
  • Increase travel speed.
  • Use proper electrode angles.
  • Use a smaller electrode size.
Poor penetration why
  • Travel speed to fast.
  • Welding current too low.
  • Poor joint design and/or preparation.
  • Electrode diameter too large.
  • Wrong type of electrode.
  • Excessively long arc length.
What to do
  • Decrease travel speed.
  • Increase welding current.
  • Increase root opening or decrease root face.
  • Use smaller electrode.
  • Use electrode with deeper penetration characteristics.
  • Reduce arc length.
Magnetic arc blow why
  • Unbalanced magnetic field during welding.
  • Excessive magnetism in parts of fixture.
What to do
  • Use alternating current.
  • Reduce welding current and arc length.
  • Change the location of the work connection of the work piece.
Inclusion why
  • Incomplete slag removal between passes.
  • Erratic travel speed.
  • Too wide a weaving motion.
  • Too large an electrode.
  • Letting slag run ahead of arc.
  • Tungsten spitting or sticking.
What to do
  • Completely remove slag between passes.
  • Use a uniform travel speed.
  • Reduce width of waving technique.
  • Use a smaller electrode size of better access to joint.
  • Increase travel speed or change electrode angle or reduce arc length.
  • Properly prepare tungsten and use proper currents.