The characteristics of common metal spot welding heads

1.Spot welding head for mild steel

Projection welding of mild steel is widely used. The following table shows the welding conditions of spherical and conical projection welding.

2.Projection welding of coated steel plate

Projection welding of coated steel sheet has fewer problems than seam welding, the reason is that the current is current is concentrated on the bumps.Even if the coated metal at the contact is first melted and diffused, there will be ni reduction in current density such as spot welding and seam welding.In addition, due to the large contact surface ans low current density of the plane electrode of projection welding, both the adhesion of the plating layer and the deformation of the electrode are relatively small.

3.Projection welding of PVC plastic surface steel plate

This kind of steel plate has an insulating PVC plastic layer on one side, and it can only be welded by single-sided single-point or single-sided double-point welding.In order to protect the adhesive plastic surface from being damaged, it is necessary to use a shorter time for welding.Generally,half a week of electricity is used to control the heat time and heat, even shortened  to 1/6 week or use energy storage welder for short time welding.In order to ensure that the plastic-coated surface does not have the same obvious indentation, the steel plate backing plate with the same pattern as the plastic-coated steel plate is usually.

4.Projection welding of other metal materials

Hardenability high strength alloy steel has rarely spot weld, but sometimes cross-welding of wires performed. Because of the quenched structure, inter-electrode tempering is necessary, and a higher electrode pressure than low-carbon steel should be used.

Stainless steel projection welding is not difficult, but it is easier to produce nugget displacement.Pay attention to the selection of reasonable welding process parameters and avoid using to small point distance.

When the strength of aluminum alloy is low, the bump is pressed and fed as soon as it is energized.It can not concentrate the current, so projection welding is rarely used.But sometimes used for spot welding head of bolts and nuts, copper alloy and titanium alloy can also be projection welded.