Issue: Excessive Indentation

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Definition
Excessive Indentation occurs when the depression left by the electrode on the workpiece exceeds the manufacturer’s specification.

Description
Indentation on at least one side of the workpiece is an essential part of resistance welding.

Acceptable indentation and the method of measurement may vary among manufacturers. The weld classification (Class A, Cosmetic, Common, etc.) may also influence the acceptable indentation. Acceptable indentation may be different on each side of the workpiece. Some electrode configurations may produce nonsymmetrical indentations (e.g. truncated cone with flat cap).

Detection

• Visual inspection
• Measurement per manufacturer’s specification

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

Possible Causes

Strong Possibilities

• Electrode faces not parallel to workpiece
• Excessive sealer
• Poor or varying part fit-up
• Weld current high
• Weld force high
• Weld time long

Weak Possibilities

• Defective air or hydraulic system
• Electrode skidding/sliding
• Inadequate or no gun equalization
• Incorrect cylinder
• Incorrect electrode dressing
• Incorrect test procedure
• Incorrect workpiece selected
• Welds wrongly located by fixture/robot/operator
• Wrong shank
• Wrong tips
• Wrong transformer