Missing Weld

Definition

A weld is missing when there is no fusion of parent metal or coatings at the intended weld location.

Description

Missing welds can occur either because:

• The welding equipment never contacted the workpiece at the intended weld location.
• Inadequate heat was developed at the intended location.

Detection

Reference should be made to the appropriate manufacturer's specifications to determine required locations for spot welds. Workpiece inspection may then determine whether visible welds are properly located or missing. Where welds are not visible (e.g., no indention or heat discoloration due to Class-A surface requirements), nondestructive or destructive test methods are required.

Significance

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

Possible Causes

Strong Possibilities

• Incorrect Workpiece Selected
• Poor Electrical Connections
• Weld Current Low
• Weld Time Short
• Weld Wrongly Located

Weak Possibilities

• Electrode Wear
• Incorrect Electrode Dressing
• Incorrect Test Procedure
• Poor or Varying Part Fit-up
• Wrong Cables/Shunts
• Wrong Transformer
• Wrong Shank

Nonmatrix Possibilities

• Inadequate training
• Improper revision level documentation on plant floor.