What is the role of a filler rod in welding?

A filler rod plays a crucial role in the welding process by providing additional material to the weld joint. When two pieces of metal are joined together, the molten weld pool needs a source of filler material to ensure that the joint has sufficient strength and integrity after the welding process is completed. This filler material helps to fill any gaps between the workpieces and compensates for material lost during the welding process, allowing for a stronger, more cohesive bond.

By adding filler rod, welders can achieve a more complete joint and increase the overall durability and stability of the welded assembly. This is essential in applications where the welded joint experiences mechanical stress or where the appearance of the weld is critical.

In contrast, the other options do not accurately describe the primary function of a filler rod. Insulation is not a function of filler rods; rather, it pertains to materials that prevent heat transfer. Removing impurities is typically addressed through other techniques such as pre-weld cleaning or using flux. Enhancing heat conductivity is related to the properties of the base metals and their ability to conduct heat, rather than the purpose of a filler rod itself.