A shank of the wrong geometry and/or alloy.
Shank: The current carrying electrode tip holder used when the tip is not inserted directly into the electrode adapter or welder arm (see figure).
Changing the shank from a male to a female tip or from a female to a male tip may change tip compatibility and/or the overall assembled length. Changing alloy material class will change the electrical and mechanical performance characteristics. Mismatched tapers will cause improper fit of the weld tips. Substituting a straight for an offset shank (or vice-versa) will change tip location relative to the other electrode. Overall length changes may create interferences or gaps between electrodes.
Wrong shank may have one or more of the following symptoms:
Quality, Workplace Issues, Cost, Downtime, Maintenance, Throughput (cycle time; PPH), are all potentially affected by this condition.