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Welding Experts?


Tom_

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Sorry if this isnt quite topic worthy but im fairly desperate. Currently doing an assignment due in tommorow (typical last minute style) its about welding processes. Iv covered MIG and TIG (its only the basics of how it works eg. how the arc is formed via short circuit between the positive electrode and the negative work piece.) However I have to cover 3 more processes. Im currently on MMA (or stick) and despite having the wonders of google and wikipedia here, its fairly hard to work out how it works having no experience with it first hand.

If anyone could enlighten me on the subject (and maybe 2 other forms of electric arc welding) then they would recieve my love forever. Either in this thread or on MSN at tom_m132@hotmail.com

cheers.

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Stick welding is pretty basic...Heat the filler rod, let it melt over the join..In it's most basic form. Quite similar to Oxy-cetylene welding..

not really as oxy-acetylene welding is more brazing, mma actually metals the metal like mig and tig and then a metal is added. oxy-cetylene just melts the filler rod to join them.

the stick is the electrode in mma and the current is passed through this to strike the arc, it can use either ac or dc depending on metal. the electrode is coated in flux and is also what is filled into the weld like you would with a filler rode in tig. as the arc is struk the flux vapourises and creates a gas shield to protect the weld. Also as you weld the electrode gets shorter and shorter as it fills the weld.

Edited by basher
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Yea, lol I was just being a retard/reading a very bad explanation. + charged consumable rod with chemical coating, touched on - workpiece, short circuit, melts, coating forms protective gas/slag. Bam.

2 other forms that are relativly easy to explain anyone?

Edited by Tom_
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Stick welding is pretty basic...Heat the filler rod, let it melt over the join..In it's most basic form. Quite similar to Oxy-cetylene welding..

that not MMA (stick) welding, you are talkng about bracing.

mma can be done either in AC or DC, unlike any other than TIG for ali. you can reverse the path of the current, i.e the arc going for the earth'd job to the stick or the stick going to the earth, this change is quite substantional.

it is essectially a metalic rod covered with a flux, meaning no need for an inert gas to form a shroud.

this is why all outdoor welding is MMA : ship building

building erection

etc.

rule of thumb is the size of the rod will produce a weld throat joint 1 mm larger than it, thus a 4.0mm rod will produce a miniu, of a 5mm weld etc

unlike MIG and TIG the positioning of the earth is critical, the quality of the eletrical earthign is effected by the distande the earth is away from the job,

uhnlike MIG and TIG you are left with bi product, namely slag, which has to be chipped off, although the sign of a good weld is the slag should be curling off aprox 10mm behind the elctrode

ask anything else,

i build pressure tested vessles for oil rigs etc

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friction welding where one section the workpeice is held still, the other is put in the chuck end of a specialist lathe type machine, the two pieces are brought together, the heat generated from the piece spinning causing friction, heats the two pieces and the pressure from the two pieces being brought together causes them to bond. pretty much it. and resistance welding (spot welding) current from two opposing electrodes, runs through the workpeices, the resistance from the work pieces on the current causes a heat build up and creates fusion between the two pieces

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