Orion Pulse Arc Welding Workbook
14
Left Image: A blunt electrode tip can be helpful when making more
powerful welds in silver to help overcome silver’s high liquid mobility by
“un-focusing” the plasma over the entire flattened area.
Right Image: A sharp electrode will help place the weld into tight
geometries, a blunt electrode can spread the energy and prevent weld
formation.
As discussed above, silver is really the major exception to having a sharp tip. Because of silver’s high liquid mobility, a sharp
electrode with a focused arc (at the very tip) will actually burrow a hole in the center of the weld spot at higher energies.
However, for small spots a sharp tip is still recommended in silver. By using a blunted or truncated tip the energy is
effectively spread over the weld area and both the burrowing hole and the thin silver blow-through can be largely avoided.
TROUBLESHOOTING THE ELECTRODE
Poor weld results are most often traced back to electrode condition and shape. Because the electrode condition is very
important, the following information will help troubleshoot problems quickly.
• During the ignition process the electrode is touching the workpiece surface when the weld current begins to flow.
e metal contaminate may form a liquid metal electrical conduction bridge. During the weld ignition process the
electrode will retract and this may lead to the vaporization of the liquid metal bridge as it is necked down during
the electrode retraction process. is vaporization process can be explosive (on a very small scale) and leaves a
crater in the metal’s surface. e result will be a small “pock” mark in the metal’s surface. e electrode must be
reground before reliable welding can continue at this setting. At lower energies this resurfacing/re-tipping may
be very important to get the welder to ignite reliably. At higher energies the welding process may proceed virtually
unhindered even with a metal contaminated electrode. To remove the small crater, weld over the crater with a newly
ground electrode.
• e electrode may stick to the metal’s surface. is happens as the liquid metal bridge cools before the electrode tip
has retracted sufficiently to leave the surface of the workpiece. A now solid metal to metal weld has taken place at the
electrode tip preventing retraction and arc ignition. is is often referred to as electrode “sticking”.
• What can be done if the weld spot doesn’t look good, asymmetric for example? is may mean the electrode may
be damaged (sharp tips or jagged edges or strange shape due to contamination). Poor tip condition can also lead to
porosity (small holes in the workpiece).
In the table below we see that trouble igniting the arc can be caused by several different reasons. e most common is a
contaminated electrode. If the workpiece’s metal contaminates the welding electrode the following may occur:
Symptom Possible Problem Possible Solution
1 Trouble igniting the arc Contaminated electrode Re-grind the electrode to remove contamination
Electrode shape not conducive
to ignition at low energy
Shape the electrode to a very sharp tip
Broken electrode, jagged edges Re-grind electrode to desired shape
2 Cratering of the weld
spot
Electrode contamination leading
to a metal bridge explosion (see
discussion)
Re-grind the electrode
Sharp electrode in a mobile
metal such as silver
Truncate the end of the electrode to help “un-
focus” the weld energy
3 Weld spot not sym-
metric
Damaged or jagged electrode Re-grind electrode
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