What is the role of a soldering iron?

A soldering iron is primarily used to provide the necessary heat to melt solder, which is a filler metal used to join two or more workpieces together. When the soldering iron is heated, its tip reaches a high temperature that allows it to melt the solder when it comes into contact with it. This melting process is crucial because it enables the solder to flow into the joint between the workpieces, creating a strong electrical and mechanical bond as it cools and solidifies.

The other options, while related to the soldering process, do not accurately describe the main function of the soldering iron. Although surface cleaning is an important step prior to soldering, it is not the function of the soldering iron itself. Similarly, while adhesives can be used in other types of joining processes, they are not the focus in soldering applications. Cooling down metal surfaces is also not a role of the soldering iron, as its purpose is focused on heating rather than cooling.