Stuck Weld

Definition

Workpieces are held together by localized fusion at the welding interface, but no weld button is formed.

Description

Stuck welds occur when there is insufficient heat at the welding interface to bring about nugget growth. Instead, fusion occurs only between point contacts between the sheets. With coated materials, coatings can melt and refreeze, effectively soldering the parts together. The resulting bonds are strong enough to hold the workpieces together under light loads, but reasonable force will pull them apart.

Detection

Pry testing or teardown will detect stuck welds.

Significance

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

Possible Causes

Strong Possibilities

• Electrode Wear
• Weld Current Low
• Weld Force High
• Wrong Tips

Weak Possibilities

• Defective Air or Hydraulic Cystem
• Dirty Material
• Excessive Sealer
• Incorrect Cylinder
• Incorrect Electrode Dressing
• Incorrect Material/Coating
• Incorrect Workpiece Selected
• Insufficient Cooling
• Poor Electrical Connections
• Poor or Varying Part Fit-up
• Poor Weld Accessibility
• Shunting of Guns or Parts
• Poor Mechanical Connection
• Weld Time Short
• Wrong Cables/Shunts
• Wrong Transformer
• Wrong Shank