Cuase of Spot Welding Failure

 Spot Welding Failure Causes:

1. Spot on radius:-

Mainly in Manual Spot welding spot position gets shifted on the radius of the mating components as there are issue to maintain position if no guide provided to Welding Gun.

2. Shunting/Shunting with part, Mylar block etc:- During the Spot Welding a suitable amount of current is required to generate enough heat to produce weld nugget. If this current leak by contacting the conductive parts of Gun to the another conductive material then required amount of current will not receive at the point of output and required heat not produce.

3. Improper Tip Alignment:- If Tip(Electrode) not aligned properly(for proper alignment Dia. should be 5-6mm in carbon test) current passed through some points which are in contact results required nugget will not formed.

4. Spot Undulation:-

5. Tip Angle not maintained with Part

6. Gap between the Child Parts:- Child part gaps where spot to be weld play a major role in spot failure. The local gap reduce the effect of electrode force and thus weldable sheet try to go away if electrode force applying on this.

7. Half Spot:-

8. Scaling on Tip

9. Gap between electrodes

10. Gun Skidding on part

11. Improper Parameters 

12. Nearby spots

13. Improper Gun Reach-ability

14. Wrong Parameters used e.g different model.

15. Wrong Gun Used

16. Improper Water Cooling

17. Wrinkle/Uneven surface of part

18. High Pressure/Electrode force

19. Abnormality in Tip Dressing Frequency

Cause of Stud Welding Fail

There are numbers of cause of Stud Welding fail it can be identify by using the tool 4M analysis.

Man

1.  New Manpower

2. Unawareness of the process

3. Less Skill Level

 

Machine

1. Wrong Weld Parameters

2. Wrong Gun

3. Wrong Machine

4. Shunting

5. Stud Gun Reach ability

6. Contact of Gun with the Sheet

7. Stud Collet Flatness

8. Lifting Mechanism Malfunctioning

 

Method

1. Difficulty to make contact angle

2. Weld Spatter Stick inside the Collet

3. No Method for Spatter Cleaning

4. Earthing Cable Loose/not connected

 

Material

1. Uneven Surface ( 30mm min. flat surface required)

2. Surface Roughness

3. Oil, Dust

4. Base Material Grade variation

5. Base Material Hardness Variation

6. Stud Head Variation

7. Stud Hardness Variation