Soldering Iron (50 Watts, High Quality) is composed of a heated metal tip and an insulated handle. Heating is often achieved electrically, by passing an electrical current (supplied through an electrical cord) through the resistive material of A HEATING ELEMENT. A soldering iron is a TOOL normally used for applying heat to two or more adjoining metal parts such that solder may melt and flow between those parts, binding them securely, conductively and hermetically.