<P> A soldering iron is a hand tool used in soldering . It supplies heat to melt solder so that it can flow into the joint between two workpieces . </P> <P> A soldering iron is composed of a heated metal tip and an insulated handle . Heating is often achieved electrically, by passing an electric current (supplied through an electrical cord or battery cables) through a resistive heating element . Cordless irons can be heated by combustion of gas stored in a small tank, often using a catalytic heater rather than a flame . Simple irons less commonly used today than in the past were simply a large copper bit on a handle, heated in a flame . </P> <P> Soldering irons are most often used for installation, repairs, and limited production work in electronics assembly . High - volume production lines use other soldering methods . Large irons may be used for soldering joints in sheet metal objects . Less common uses include pyrography (burning designs into wood) and plastic welding . </P> <P> For electrical and electronics work, a low - power iron, a power rating between 15 and 35 watts, is used . Higher ratings are available, but do not run at higher temperature; instead there is more heat available for making soldered connections to things with large thermal capacity, for example, a metal chassis . Some irons are temperature - controlled, running at a fixed temperature in the same way as a soldering station, with higher power available for joints with large heat capacity . Simple irons run at an uncontrolled temperature determined by thermal equilibrium; when heating something large their temperature drops a little, possibly too much to melt solder . </P>

What can you use a soldering iron for
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