What is arc welding? Today I'm going to be talking about and demonstrating shielded metal arc welding that's sometimes referred to as stick welding. Arc welding creates heat for the welding process through a process of electrical resistance. The arc welding machine builds up electrical potential in the same way that all of you have experienced by shuffling your feet on a carpeted floor and touching you hand to the door knob and receiving that rude shock.
The arc in arc welding comes from the fact that the electricity literally jumps from one object to another completing a circuit. To complete this electrical circuit, the arc welder has two different leads. Their ground clamp, which is attached to the table, or to their work, and your electrode holder, which holds the electrode, which completes the circuit.
Now I want to talk to you about set up and operation of the welding machine. What you're looking at here is a typical AC-DC arc welder. Up on this side of the welder there's a handle where you can change the type of current that runs through the machine. Most of the welding processes we're going to use use simple AC current. That is the same kind of current that comes out of the outlets in your house and runs your lights.
This welder can also be set to DC positive, or DC negative, which actually controls the direction the electricity flows through the leads of the welder. This is used for certain specialty processes such as welding aluminum, bronze and cast iron for the appropriate specialty rods.
Every arc welder has an on/off switch. On. Off. Also some way to control the amp ridge. All right? Down here on the bottom of the welder you can see two scales. The upper scale is an AC amp ridge and the lower is a DC amp ridge. Amp ridge measures current not voltage.
By turning this wheel clockwise I make the level of current and therefore heat go down. By turning it counterclockwise, I turn the current up. I make the weld hotter. Most welding that we'll talk about that people do on a day to day basis operates at fairly low amp ridges somewhere between 70-100 amps. The thicker the material, the higher the heat, the thicker the rod.
A crucial part of the arc welding process is the welding electrode. The electrode has two components. It's metal alloy core surrounded by a hard flux. During the welding process as the metal alloy rod melts, the flux core burns. As it burns it creates an inert atmosphere at the welding tip that allows the metal to flow.
The melting alloy rod and the flux can create very obnoxious and irritating fumes and you should avoid breathing them directly if at all possible. It's very important to have adequate, sufficient ventilation when performing a shielded metal arc welding.