Spot welding creates overlapping seams which, when immersed in electroplating solutions, trap solution residues through capillary action. This creates two problems. First, the residue often leaves plating salt deposits which are unsightly and which, in extreme cases, may require touch up or manual removal at increased cost. Second, the metal in the seam is unprotected and can corrode severely in harsh environments. When designing spot welded assemblies for electroplating, consideration must be given to plating drainage, enclosed seams and pockets, overlapping seams and other areas where solutions may be trapped or where special cleaning or processing techniques may be required. When these operations are combined, early consultation with an experienced supplier is crucial.
Position the welding torch with the wire in the center of the hole contacting the back sheet of metal. It is important to arc against this back sheet rather than on the edge of the hole, otherwise the weld might not penetrate into the back sheet. The torch should ideally be pointing directly into the hole rather than at the angle in the photograph. Start welding in this position and don’t move the welder until the hole is almost full of weld. Then move the welder outwards in ever increasing circles until the weld is completed.
How Does Spot Welding Work? A form of resistance welding, spot welding is one of the oldest welding processes whereby two or more sheets of metal are welded together without the use of any filler material. The process involves applying pressure and heat to the weld area using shaped alloy copper electrodes which convey an electrical current through the weld pieces. The material melts, fusing the parts together at which point the current is turned off, pressure from the electrodes is maintained and the molten “nugget” solidifies to form the joint. Read more details at Tecna Spot Welder Parts.
Stationary spot welders are mounted on a column with a jack and mobile arms. The frame is heavy and bulky and the machine has a welding capacity of 0.5–10mm. The body of the machine often equipped with a 380V generator and two arms with a mechanical, pneumatic or hydraulic jack to adjust operating height, as well as heat-resistant electrodes made of copper or copper-chromium alloy. No electric arc is produced, and the arms are water-cooled in closed circuit. The arms and electrodes are interchangeable to vary spot size and form across different types of weld.