Generally (but not always) pronouns stand for (pro + noun) or refer to a noun, an individual or individuals or thing or things (the pronoun's antecedent) whose identity is made clear earlier in the text. For instance, we are bewildered by writers who claim something like. They say that eating beef is bad for you.
A wire feeder may be used for machine or automatic welding and must be the constant speed type. The wire feeder must have a speed adjustment covering the range of from 10 in. per minute (254 mm per minute) to 125 in. per minute (3.18 m per minute) feed speed. PAW or plasma arc welding using an automated process.
MIG welders use a wire feed to supply the well material. There is a spool of wire that is fed through a long cable and out of the welding torch, basically a wand with a trigger on it to control the feed of the wire. When the wire hits the metal you're working on, the arc is created and you're welding.