Relief spot welding

Relief spot welding This is a type of resistance welding that involves heating and applying pressure to two parts. In this welding method, the surfaces being joined have specially prepared reliefs. These reliefs can be located on one or both parts. Relief spot welding Used in automotive manufacturing, electronics, and other industries, it's a practical way to attach brackets to sheet metal parts, as well as studs, bolts, and nuts. In industrial electrical engineering, it's used to attach wire to thin components.

The technological process proceeds in the following order:

• Reliefs are pre-stamped onto the workpiece to be welded. These projections can be annular, circular, oblong, or otherwise. The metal relief must be sufficiently clean of any dirt or grease stains. Various impurities on the surface prevent proper heating and a strong bond.
• The workpieces are then clamped. These clamps serve as plate-shaped electrodes. Electric current is applied;
• The welding current intensely heats the raised protrusions, which begin to undergo plastic deformation. Contact resistance decreases, and the melting zone increases;
• The welding current is turned off when the molten zone has reached the required size. Compression produces the joint. Crystallization of the metals being joined occurs in the molten zone.

Unlike resistance welding, in projection welding, the joint is determined by the size and shape of the projection, not the surface of the welding electrode. This method results in longer-lasting welding electrodes, as the contact surface is larger and the current is concentrated on the raised features of the workpiece.