There has been a lot of confusion i think in what welding is, and what the do's and dont's are to welding in general. A lot of people wanting to get started, make there own stuff ect.. and need a little guidance into welding. This is only my opinion, and stuff that i have learned thru out the past couple of years as i work towards my welding engineering degree. ok lets get started.Mig welding: Also known as gmaw or gas metal arc welding. An arc created between a continiously fed filler metal and and the weld pool. either has an externally supplied shielding gas with or without pressure
*Uses heat of the continuosly fed electrode and the work piece
*Arc melts the base metal
*The melted filler material is deposited into the weld pool
*An external shielding gas must be supplied (usually a co2 argon mix)
*Gas can be active co2 or argon base wich is considered and inert gas
*inert gas: a gas that does not change no matter what the conditions in heat.
Types of transfer for the gmaw process:
*Short circuit: This is the most common type of transfer. Uses .023-.045 dia wire. Fast frrezing puddle with minimal distortion. Metal only transfers when contact is made between the base metal and the filler metal. Happens at the lowest welding current and volts 14-23 v and 100-270 amps. Sounds like crackling bacon when you are welding.
This is what it looks like.
Equiptment needed:
Power source- Constant voltage, variable amperage direct current.
Wire feeder-Deliver filler metal at a constant speed to the puddle. Controls gas flow.
Welding gun (torch)-Carries electrode from feeder to the weld pool. Also delivers gas and the electical power to the weld zone.
Gas supply-Inert or active shielding gas with a regulator or flow meter.
Wire supply-This is determined on the process that you are doing, and should be consulted with your local welding dude that know's what he is doin.
Globular transfer: This is the first transfer that came out. And is rarely to never used on here. It is exactly what it is. Glob's of shit on your metal.
*Higher voltages and wire feed speeds 22.5v-24v and 165-365 amps
*Metal starts to transfer thru the arc and forms into large droplets onto the metal.
*Produces heavy spatter and has a very unstable arc
Looks like this
Spray arc transfer: Highest voltage and amps 24 volts and above with 135-500 amps
*Uses 5% to 10% co2 mis with argon or oxyegen.
*Forms very small droplets of metal
*Very good stability
*Very little spatter
*Limited on positions of applications tho.
*needs better equiptment to run this process.
looks like this.
Pulsed mig: Newest type of transfer.
*Current switches between a high and a lower value
*Low value is below the transition point of the electrical cycle and there is no transfer fo metal in this stage.
*Higher value Is higher than spray arc transfer and this is where the transfer of metal happens.
*these cycles can happen between 60-3000 times per second.
*This also requires a special power source and is not really needed for the do it yourselfer, but if your on a production line, and you go from 50 lbs an hour with short circuit transfer, and you switch to a power source or transfer type that can produce you twice as much weld with better quality the investment is worth it.
The transfer looks like this.
Keep in mind this is all generalized, and people are coming out with such new stuff now days that the welding industry is almost changing as fast as computer technology. Such as millers new accupulse transfer that i just got to try out yesterday. It was amazing, and is a transfer between pulse spray and short circuit all in one. It is truely amazing.
Mig welding has also adopted some new types of filler metal into the welding family.
Metal cored wire: New filler metal family that combines the efficiency of solid gmaw wires and the productivity of flux cored wires.
Lower fume generation
95-98% efficiency rating
No slag
Reduced cold lapping
Improved sidewall fusion.
This is done in the spray transfer mode and provides litttle to no spatter whatsoever.
This wire is a tubular wire with metallic element filler in the inside of the wire to match different welding applications.
Concept of this: Nearly all electiral current travels thru the outter shell of the wire, while the metallic filler in the middle mixes in with the puddle so you can weld different alloyed metals. Gets better wider slightly shallower penetration profile.
Flux cored wires:An arc between an continuously fed filler metal and the weld pool. This process is used with a shielding contained in the tubular electrode and can be used with our without an externally supplied shielding gas depending on the wire you are using. A lot of the harbor freight cheepo welders use fluxcore.
You may see it like this. FCAW-SS=Self shielded
FCAW-GS=Gas shielded
The fluxing is contained on the inside of the wire, and the flux covers the metal after you weld it to protect the weld from the atmosphere causing porosity and such. Must be chipped off like a stick weld.
Filler metal reading. If you ever look at your filler metal you may see some different types of letters and numbers. Well these do mean something and here is what they mean.
For example.
E70t-10
Ok here is what goes down.
E=electrode
7=Tensile strength usually x's 10 or ksi
0= Flat or horizontal position filler metal if it was a 1 it is all positions
T=In this one it means it's a flux cored wire.
10=Indicates performance and usablility of the filler metal.
Modified by jaydmcrx at 10:52 PM 4/19/2006
w00t for a michigander 
this is sticky material 
