Cause: Wrong Caps or Electrodes

One or both of the electrode tips installed is not of the design or material intended for the application.

Same as: Wrong caps, improper electrodes, etc.

Description 

Electrode tips are available in various shapes, sizes, and materials to suit the design of the welding equipment, the geometry of the parts being welded, or the material being welded. Substitution of an inappropriate tip may adversely affect the available current carrying area, the parallelism or alignment of the tip faces, the amount of current required, or the shape of the resulting weld.

Detection 

Detectable evidence may include:

• Excessive indentation
• Expulsion/burn through
• Cracks & holes
• Mislocated/edge welds
• Sheet metal distortion
• Poor Class A appearance
• Sticking/stuck tips
• Stuck weld
• Undersized weld
• Visible mismatch of tip faces when the welder is closed (face shape, size, nonparallelism, misalignment)

Significance 

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

Quality:

• No-welds or undersized welds
• Excessive indentation and expulsion may weaken the weld and be visually unacceptable
• Edge welding

Workplace Issues: 

• Edge welding may result in heavy expulsion leaving sharp edges

Cost:

• Reduction in tip life, increasing welding costs
• Undersized welds may increase levels of rework

Downtime and throughput:

• Wrong tips may have to be changed immediately, necessitating downtime
• Excessive sticking may occur
• Any downtime will reduce throughput