Why are backing bars or plates typically made of copper?

Backing bars or plates are typically made of copper primarily due to its high thermal conductivity. The high thermal conductivity of copper allows it to efficiently dissipate the heat generated during the welding process. This is crucial in preventing excessive heat buildup in the workpiece, which can lead to warping, distortion, or even damage to the material being welded. By effectively removing heat from the weld area, copper backing bars help maintain the integrity of the weld and the surrounding material.

While factors such as cost, strength, and weight may play a role in material selection, they do not match the importance of thermal conductivity in the context of weld quality and performance. The heat distribution characteristics of copper contribute significantly to successful welding operations, making it the preferred choice for backing bars or plates.