Contaminated welding surfaces will not allow sufficient welding current penetration. Remove paint film and rust by sanding the areas being welded with a small belt sander.
Use tools like vise grip welding pliers to tightly clamp parts being welded.
2.
Condition of Welding Tips:
Make sure there is no contamination, damage or deformation of the welding electrode tips before use.
When the of the welding electrode tips degrades with use, current flow is reduced, resulting in poor welding nugget quality.
Dress or replace the electrode tips, before each use to ensure optimal welding performance.
3.
Setting Arm The arms selected must adjust to allow the welding electrode tips to align in a straight line.
4.
Welding Pitch:
When spot welds are place too close together, some of the welding current is “shunted” through the previously-welded spot. This current is then not available to complete the spot weld being made, resulting in a weaker joint. Check the welding conditions compared to the chart below and adjust as necessary to prevent shunted current.
When the spot is too close to the edge of flange, the nugget overflows outside the flange surface reducing the welding strength. Weld spot must be located on the center of the weld flange.
The welding pitch (distance between the spot welds) and the distance from the flange edge must be set according to the material thickness. Use the chart below as a reference for spot weld location and pitch.
Spot: Weld Location Chart (assumes 2 layers of equal thickness)
Thickness mm (in)
Pitch P mm (in)
End Distance E mm (in)
0.6 (0.024)
11+ (0.43+)
5+ (0.20+)
0.8 (0.031)
14+ (0.55+)
5+ (0.20+)
1.0 (0.040)
18+ (0.71+)
6+ (0.24+)
1.2 (0.047)
22+ (0.87+)
7+ (0.28+)
1.6 (0.063)
29+ (1.14+)
8+ (0.31+)
When you are making a number of spot welds at once, be sure to check the spot welder’s settings and allow adequate space between each weld.
When doing spot welding, check the shape and condition of the welding electrode tips often.
