Welding, Brazing and soldering .... what's the difference?

[wanabechippie]

'Allo peeps!

Looking at expanding my bodging skills by having a bit of a dabble in metal work. Aquired some 16mm box in 2mm-ish steel and fancied having a play about.

As regards joining metal, what's the difference between welding, soldering and brazing? Also, with welding, what are 'mig', 'tig' 'ark' and 'spot' all about?

What sort of kit do you need to do the above methods of joining?


You may now begin. No conferring.

 

[breezer]

soldering uses ...........solder, great for electrical connections, but its a very weak joint for anything else

braing is if you will "one up" from soldering, it does give a stonger joint

ARC is when you use the power of electricity
you must know if you make a short on an electrical supply it goes bang?
well with arc welding it doesnt, since there are no fuses, you "strike" the arc by touching the welding rod to the work, then pull the rod slightly away, creating an arc, this arc takes metla from the rod and puts it where you are pointing (if you will) very strong joint

spot is where a "clamp" clamps the work and passes a very high current through where the clamp touches, it gets so hot the metals melt joining to each other

tghe rest i donrt know.

well the above is my understanding of it

 

[JohnD]

"Soldering" "Silver Soldering" and "Brazing are all the same thing (sort of).

They work by using a metal with a relatively low melting point (so that the substrate is not melted, unlike welding), that alloys with the metals being joined. So a solder is not just a "glue", it actually alloys with the metal components at the interface. So when soldering together two pieces of copper you might have:
copper substrate... copper/tin alloy... layer of solder... copper/tin alloy... copper substrate

The weakness arises because soft solders are quite weak, and the failure comes about not from the solder failing to stick to the substrate (if it has been properly done) but by the weaknes of the solder layer.

Hard soldering /silver soldering/brazing are stronger because the "solder" used is harder and stronger and less liable to tear. Lead solders are particularly weak, and so a mechanical joint (by lapping or hooking together) is common, with the solder stopping the mechanical joint from coming apart. Gold is sometimes soldered using alloys which contain 33% or 75% gold, and these can be about as strong as the jewellery they join.

there are some oddities, like old, tin-plated copper wire being difficult to solder, because the tin molecules have migrated into the copper, and the surface is fuly alloyed, and will not alloy with the solder until abraded away.

Alloying with the substrate is why absolute cleanliness is so important. tinning the components helps to get a thorough alloying. some materials, like Stainless Steel, and aluminium, ae dificult to solder because they quickly form an oxide surface layer which will not alloy. special fluxes are needed which will break this down for long enough for the hot solder to flow over the surface.

 

[Trazor]

Mig welding, is where a filler wire is fed, by pinch rollers, from a coil, through a copper tip, this is surrounded by a gas shroud.
An inert gas (usually Argoshield) is then fed through the shroud, covering the welded area, so preventing air reaching the weld.
When pressing the trigger of the welding gun, the filler wire touches the steel and strikes an arc, so melting the wire and the steel you are welding.
This process actually melts your 2 pieces together, so providing a very strong joint.

Tig welding, uses a tungsten tip, again surrounded by a gas shield.
When pressing the trigger, a plasma arc is formed at the end of the tungsten tip, which then melts the metals together.
If required, filler wire is usually fed by your other hand, as in gas welding.

 

[wanabechippie]

Wow! Thanks alot for all that, guys!

Are there any benefits/more suitable tasks for using mig in stead of tig? Is one more of an all-rounder than the other or does it depend on the task?

Is welding dangerous? Gopping great bolts of leccy dancing around the place does sound a wee bit on the risky side! How easy is it for someone with only basic electronics soldering experience to pick up?

Any suggestions as to entry level welding kit, either mig or tig?

Questions, questions....

Muchos cheerios.

 

[JohnD]

holes in your socks are most common.

eye damage (arc-eye) can be very painful.

 

[Trazor]

For welding mild steel, MIG is the easier, and more versatile option.
MIG welders are rated in Amps, the greater the amperage, the thicker the steel you can weld.

Tig is a harder skill to learn, especially when using a filler wire.

Neither is electrically, any more dangerous than using any corded appliance.

Buy a leather apron this will protect your clothes. Buy a pair of welding gauntlets, although if you are right handed, you will only use the left one............
If you can afford it, buy an auto shading helmet, this darkens as you strike an arc, saves lifting your helmet up and down.

And as JohnD says, holes in your socks are most common, but trust me, you will never remove a shoe faster in your life, once that little ball of very hot steel gets inside............

 

[wanabechippie]

Neither is electrically, any more dangerous than using any corded appliance.

Really? Surprised by that. Would have thought it would be akin to playng near bare, live cables. What would i have to do in order to get a shock?

, but trust me, you will never remove a shoe faster in your life, once that little ball of very hot steel gets inside............

Ah-ha! Sandals it is then!

So roughly what ampage would i be looking at for mig welding 1-3mm ish steel then?


Thanks for all this, everyone! Really appreciated!

 

[Trazor]

Really? Surprised by that. Would have thought it would be akin to playng near bare, live cables. What would i have to do in order to get a shock?

Everything is shielded, except for the end of the earth clamp, which must be affixed to the job you are welding.
If you hold the metal you are welding with your bare hand you will still not get a shock, but you could well get burnt.......
Never weld outside if it looks like rain.........

Ah-ha! Sandals it is then!

Noooooooooo......... the balls of hot spatter will stick to your socks, especially nylon socks. Wear boots, and make sure your trousers overlap the top of your boots.

So roughly what ampage would i be looking at for mig welding 1-3mm ish steel then?

100 Amps will more than suffice.
Do not buy a machine which is rated to weld the maximum thickness you wish to weld, much better to run the welder at about 60 to 80% of its capacity.

 

[broxy]

Have a try with an Arc set, cheap to buy and no extra gas to buy if using MIG unless of course your using flux cored wire.
It takes a bit of an knack to get used to it, slag holes etc but you'll soon get the hang of it and watch that old slag peel of behind the weld.

 

[Hitachimad]

Have a look at this website...

http://www.mig-welding.co.uk/forum/profile.php

Mig/mag, tig, mma, gas, brazing.... its all prettymuch covered there....

Any questions, feel free to post them up for us to answer.

 

[wanabechippie]

Ah-ha! Sandals it is then!

Noooooooooo......... the balls of hot spatter will stick to your socks, especially nylon socks. Wear boots, and make sure your trousers overlap the top of your boots.

Aww! But tis the season for nylon socks and sandals!



Cheers for that. That's a great site, Hitatchimad, Thanks.

Think after all the info from here and the welding fourm site, i'm going to go for a 90-100 amp gas mig welder. Apparantly gas'd migs work better on the thinner mild steel that i'm looking at working with? might look at a combi MIG. Any opinions on gassless MIGs? Gassless wire?


Thanks all!

 

[Hitachimad]

If you go with a gass'ed model, i doubt youll never bother to use gasless. Gasless is crap anyway.

 

[andyandy2]

I've used arc, gas (oxy-acetylene) and mig welders over the years, I find the arc welder very useful for small repair and fabrication jobs as long as the metal is not to thin, as long as the rods are kept dry, i have few problems. Mig welders i used to use for car body repairs, they take a bit of getting used to setting wire speed and gas flow, and make sure you always turn of the gas at the cylinder to prevent any loss through leakage, BUT the one problem i had with the mig if i didn't use it for awhile was that the coil of welding wire would go rusty, although its copper coated mild steel, ( might depend on the quality of wire you buy) it then gave problems feeding through the machine