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Arc or Mig?
Eeyore:
--- Quote from: "karloss" ---
The gas used in an (incorrectly named mostly :roll: ) MIG welder is there purely as a shield to prevent the oxidation of the weld pool whilst at it's most vunerable (above red heat). It has nothing whatso-ever to do with the ammount of penetration.
--- End quote ---
Hmm, a sweeping statement that I'm gonna have to disagree with I'm afraid. :-k Gas not only sheilds the weld (on any arc based process, save electrodeless ionic) but can determine the shape of the weld pool and consequently, the depth of penetration for a given set of parameters. Try running a gas mix containing hydrogen and see how it goes! Now, of course, as a welder it might not have sufficient impact on your process needs to worry about, (and many aren't, but in aerospace and other similar apps using freaky materials, it's kinda vital) but its affects can be significant. :wink:
To answer the question, my view is to go for MIG as its a far more adaptable process. I found it easier to pick up, too. Unless you spend oodles of cash though (I mean thousands), welding of strutural aluminium will be a no no, I'm afraid. I've yet to see decent ali welding from an unpulsed arc source (MIG, TIG, Plasma, CMT). TIG is far more afordable for good ali joints. And also very good for steel. And easy to learn, but that doesn't answer your question!
As has already been said, just make sure your weld zones are free from contaminents (oils, underseal, rust, scale etc) otherwise your weld will look like a bird poo / swiss cheese hybrid - which isn't good!
The one thing I would suggest, is to try your local tech colleges for short welding courses - many operate them. Could be a good source of leanring and experience.
cheers
8)
Eeyore
Ja1983:
i have a lil old arc welder, tis of the "sip" DIY variety, and while it took me a while to get the nack, i find its fine unless your welding thin stuff,
hopefully the big fat guy who brings pressies will be leaving a gasless Mig for me this year, so will give it a bash, and if all goes well i`ll be re-building the pickup! :lol:
karloss:
--- Quote from: "Eeyore" ---
Gas not only sheilds the weld (on any arc based process, save electrodeless ionic) but can determine the shape of the weld pool and consequently, the depth of penetration but in aerospace and other similar apps using freaky materials, it's kinda vital) but its affects can be significant. :wink:
--- End quote ---
Areospace? Freaky materials? Whooa dude. We were talking about welding a rusty old land rover!! :wink:
As for the weld pool, that's going to be affected far more greatly (here's an egg grandma) by the arc length and work/stroke angle. And even more so by the ability of the person welding to not flinch at red hot bits of the aforementioned rusty landy falling down his/her back!!! :lol:
On automated processes, yes, gas is an important, nay vital consideration. On your back, on the drive, under the land rover, using a welder you bought from the local diy supplier, I stand by my original sweeping statement. It aint gonna matter a jot wether you use a mix or a pub bottle. (but then you already knew that :wink: )
karloss:
--- Quote from: "nzrover" ---
--- Quote from: "karloss" ---Spray transfer? On a car body/chassis? I think not.
--- End quote ---
No problem on a chassis, and essential if you start welding up engine mounts, towbars and recovery points.
--- End quote ---
You need 250 amps minimum for spray transfer.
Hangover:
Buy a mig and if you can use it great,if you can't use it give it to somebody who can and let them do it.
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