Projection welding is a variation of resistance welding in which current flow is concentrated at the point of contact with a local geometric extension of one (or both) of the parts being welded. This article focuses on the process fundamentals, advantages, and limitations of projection welding and reviews the equipment used in the process. It discusses projection welding of copper and copper alloys, aluminum and aluminum alloys, and steels. The article provides several specifications and recommended weld schedules and practices for projection welding. It describes the embossed-projection welding of heavy-, intermediate-, and thin-gage sheet mild steel as well as the welds between dissimilar thickness joints. The article also considers the solid-projection welding of steels: annular, nut, and cross-wire projection configurations. It also details the various tests that can be used to validate projection weld quality.

Projection welding (PW) is a variation of resistance welding in which current flow is concentrated at the point of contact with a local geometric extension of one (or both) of the parts being welded. This article discusses the applications of PW generally categorized as either embossed-projection welding or solid-projection welding. Different projection-welding configurations are schematically presented and the common variations of solid-projection welding are described. The article describes equipment used and the process requirement for the PW. The process requirements for projection welding of a range of intermediate-gage low-carbon steels are presented in a table.