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Definition
The weld button/nugget diameter does not meet applicable specifications. (The weld nugget is the fused volume that joins the workpieces. The button is the material remaining attached to the fused area after destructive sheet separation.)

Description

Detection
The button diameter is determined by measurement after teardown; nugget diameters may be determined by sectioning the weld. Consult the applicable specification for appropriate measurement method and size requirement.

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

Quality: Button diameter is the key measure used to control spot weld quality in the plant.

Possible Causes

Strong Possibilities

• Damaged part
• Defective air or hydraulic system
• Dirty material
• Electrode faces not parallel to workpiece
• Electrode skidding/sliding
• Electrode wear
• Excessive sealer
• Incorrect cylinder
• Incorrect material/coating
• Incorrect test procedure
• Insufficient cooling
• Poor electrical connections
• Poor mechanical connection
• Poor or varying part fit-up
• Poor weld accessibility
• Shunting of guns or parts
• Weld current low
• Weld force high
• Weld time short
• Wrong tips

Weak Possibilities

• Incorrect electrode dressing
• Incorrect workpiece selected
• Poor electrode follow-up
• Wrong cable/shunts
• Wrong shank
• Wrong transformer

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Information presented by Production Engineering
www.ResistanceWeldSupplies.com