In resistance seam welding, which method employs a series of overlapping spots to form the weld?

In resistance seam welding, the method that utilizes a series of overlapping spots to create the weld is stitch welding. This technique involves creating multiple weld spots in a linear sequence along the joint of two metal pieces. These overlapping spots are essential as they provide a continuous weld bead that is stronger and more durable than individual spot welds alone, which could create weak points between spots.

Stitch welding is particularly useful in applications where a strong seam is required over a longer distance, such as in the manufacturing of sheet metal parts. By overlapping the weld spots, the technique ensures that the entire seam is securely bonded, reducing the risk of failure under stress or load.

Other methods like roller welding and spot welding focus on different ways of joining materials but do not involve the specific technique of creating a series of overlapping spots like stitch welding does. Projection welding is also distinct as it relies on raised features on one of the workpieces to create localized welds rather than a series of continuous spots.