school me on welding

[Even]

Alright now that i'm learning how to, i would like to shed some light on the subject with a bunch of questions.

Why does arc welding create slag and mig/tig doesn't?

What is the difference between mig and tig, i was under the impression both use wire?

What does duty cycle mean, on my welder the duty cycle decreases as the amperage increases.

[Fuzzy Wuzzy]

arc has no shielding gas, and when the electrode hits the ground, a mini explosion is created, if you will. it melts the electrode and that what you're welding to. the shielding gas in mig process tunes down this "explosion".

mig uses the wire as an electrode and is added to the material and tig has it's own electrode and wire is added to the melted material.

duty cycle is how long a time the tool may run at full capacity, safely and well.. at full capacity.

[CumminsJeep]

hopefully stinky comes back haha he is goood

[stinky]

signatures say it all...

STICK: the slag created after the weldement is created, is from the flux composition that is located on the stick rod. the flux is full of alloys and chemicals that created an inert "cloud" or "smoke plume" around the molten puddle and arc, if there was no inert cloud or atomsphere was allowed it, you get porosity, which is either oxygen, hydrogen and or nitrogen, any combo of those 3 and youre fuct...after the weld pool cools, the slag forms over the bead, which also helps aid in avoiding the rapid cooling of the weld nugget, which causes stress cracks, not good...the arc is used to melt away at the base metals and create a "pocket" if you would, for the actual weld nugget to fuse each together, most of the sparks you see are the base metals being blown out from the arc, and the electrode is used to carry the current from the stinger to the workpiece and is the main deposit in a weld

MIG: is a semi automatic process, meaning that the actual filler wire is fed via the machine (unlike stick, in which the electrode is consumed and must continuously be fed into the the material by the weldor)... so all the machine or person has to do is manipulate where the arc and filler material go, and how fast the deposition rate is (how much metal is being deposited), varies the travel speed and amperage...along with base metal thickness. Very much like stick, mig creates an inert atmosphere at the arc, where the same 3 contaminants can ruin the soundness of a weld. the current, shielding gas and wire is fed to the gun where the electrode (wire) glides through a contact tip, which transmits the current to the electrode where 1/2"-3/4" later it is arc'd off the base material and deposited.

TIG: uses an inert gas cloud, usually straight argon, or a mix, and uses a piece of tungsten(which melts around 6000+ degrees) to create an electrical arc, that forms a molten puddle, in which a filler wire is dipped into the puddle, creating an actual weld deposit. tig can be used in a strictly fusion welding process, where the base metals are just melted together, sans filler wire. tig is the surgical type of welding, surface contaminants will ruin a tig weld in a split second, so everything has to be clean as a whistle... the tig wire is usually manually fed into the weld pool as needed and on some robotics setups it has an automated wire feed system (which is fucking titties, and a bitch to dial in, especially on an orbital pipe machine)...most tig welding is dont on materials that have to put up to extreme pressures, have to me clean as hell, such as medical or nuclear, or for someone who wants a surface weld to be extremely small and cosmetically appealing.

DUTY CYCLE: my my myyyy...one of the easiest concepts in the welding field and somehow people find a way to fuck it up... duty cycle is the time allowed for a machine to safely, efficiently and reliably run without overheating the internals(such as transformers).. duty cycle is not just what a machine will do flat out, it is how long a machine will perform at a said amperage or voltage output for a given amount of time.... some machines say that at 100% output they have a 60% duty cycle, ok, then you can run the machine on the rev limiter for 6 minutes, continuously, but then it needs to sit, RUNNING, for 4 minutes to cool off, then repeat... another example, some 220 mig machines put out 160 max amps, which means if its got a 60% duty cycle balls out, at 80 amps, its almost doubled, and at quarter power, 4 times that...get where im goin??.... the lower the machine's output is set, the longer it can continuously be ran

thats just what i pulled off the top of my head in about 8 minutes haha

and not trying to be a dick, but lets keep this thread anti- ...b/c a lot of people like to build their own shit, and the last thing i want is a jeep or truck come blowing into my lane on the road b/c some idiot booger welded his front axle in his vehicle and the weld broke, nor do i wanna hear about people dying in a car accident from the same situation... get my drift?? its something that most people overlook and it definitely shouldnt be

[stinky]

haha yes andrew, i have spoken

[CumminsJeep]

thanks koup

[ninetysix-ex-jay]

Arc makes a lot of slag. A shielding gas is created when the flux around the electrode is burned. This causes oxygen to be dispersed. Mig still creates a bit of slag. Get a chipping hammer to remove it. If you arc welding skills are good, one swing of the chipping hammer should remove the slag. Wire brush it after chipping it. DO NOT WELD OVER SLAG EVER EVER EVER!!!!

Basically, in Metal Inert Gas (MIG) welding the electrode becomes a part of the weld and in TIG or Tungsten Inert Gas, the electrode is just used to heat the metal. Tig requires more skill then MIG which is basically point and shoot. MIG also auto feeds the wire and in TIG you feed the wire.

Duty cycle is the percent time (in a 10 minute span) that the welder can operate at peak current. For example a 100Amp welder with a 50% duty cycle can operate at 100Amps for 5 minutes.

My best advise is take a welding course. Thankfully, my school required it so thats why I know all this "useless" information. Check out "tony's welding series" on google or something. Its videos and the guy gives a pretty good into to welding.

[ninetysix-ex-jay]

Stinky beat me to it....if I knew that I wouldn't have wasted my time

[stinky]

haha its all good, its not rocket science, but its harder than most think, and understanding the concepts of it, makes fixing problems on the fly, a breeze...not to mention, makes a much more sound weld that can actually be relied upon

[ninetysix-ex-jay]

Hey stink how do you know what to set the current to on a ARC welder when you first start off. Any rule of thumb for the thickness of the metal? I typically use 7018 rod if that makes a difference

[stinky]

thickness of metal decides how big of a rod to use, once you figure out what size rod youre using, the amperage is set according to the rod diameter...

what thickness material you usually run?? and what size electrodes?

[ninetysix-ex-jay]

The stuff that I weld is typically on ships so its usually 1/4" - 3/8" I'm not sure of the electrode size off the top of my head. Next time I go on the ship I can let you know