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.
On the other hand, FCAW uses a tubular wire that has flux in the middle. The flux then burns, emitting a shielding gas, which protects the puddle. The flux turns into slag, just as in the shielded metal arc welding (SMAW) process. Shielding gas is not necessary, but it can be used to make a bead even smoother.