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.