Sticking/Stuck Tips

Definition

Sticking is a term that refers to the tendency of the electrode tip to adhere to the workpiece.
Same as: pick-up.

Description

Elevated temperature at the electrode/workpiece interface can produce alloying conditions. Zinc coating allows a zinc copper alloy to develop at the electrode tip, promoting adhesion of the tip to the workpiece.

When bare steel is welded, a carbon layer forms on the tip. This layer acts as a barrier to fusion of electrode and workpiece, thereby minimizing sticking.

Sticking may also result from melting and refreezing of the workpiece coating [e.g. zinc], prior to tip removal from the work piece. Detection

  • Gun will not open
  • Part pulled from fixture
  • Gun open; Tips stuck to work piece
  • Water flowing from electrode
  • Machine control fault
  • Irregular weld

Significance

Quality, Workplace Issues, Cost, Downtime, Maintenance, Throughput (cycle time; PPH) are all potentially affected by this condition.

Possible Causes

Strong Possibilities

Weak Possibilities

Nonmatrix Possibilities

  • Heavy galvanized coating
  • Inadequate tip cooling
  • Insufficient edge distance to weld
  • Low clamping force
  • Low conductivity tips