Arc welding 3mm sheet steel

[snowcat]

gavuk - you are right and I look forward to trying the MIG in due course. I think my interest in arc stems partly from it being seen as the underdog. The other reason is its welcome simplicity with fewer variables, and significantly lower running cost per inch of metal joined together.

Emmm MIGS the cheaper George, due to the speed, and consumable cost, arc very much has its uses they just tend to be different applications...

 

[Drains]

Emmm MIGS the cheaper George, due to the speed, and consumable cost, arc very much has its uses they just tend to be different applications...

BUT Snowers, for the low end user, MMA is cheaper, once you take bottle rental and that into account, also initial investment.


Got to agree, in an industrial setting, mig is the bunny when it comes to squirting out a standard weld, or a high volume special.

 

[runnach]

I also read something somewhere that the root is often applied with TIG. Is that because it's easier to achieve a more precise placement? Then the next layer can be arc or whatever, if I understand correctly.

Root run, hot pass using tig is normally getting more into the professional side of the welding game. Processes used will be dependent on material type and use of end product, more importantly, what is contained within weld procedure sheet, which will have been put together by welding engineer, determines processes to be used. For example, pipe is rooted and capped using MMA, this is good enough for H&V industry, to use tig for root would not be cost effective, plus MMA suits H&V industry standards, more to it than the above, but this about sums it up. A good welder will apply a sound bead using any process within his skill frame.

From my days when on the tools, for subsea template equipment, diving habitats for example, i would basically follow WPS.

 

[GeorgeB]

Emmm MIGS the cheaper George, due to the speed, and consumable cost, arc very much has its uses they just tend to be different applications...

Simon may have beaten me to it! I admit that time taken is left out of my assessment. Other costs:

Purchase cost: Arc - mine £19, normally £45. Mig about £250. Arc wins hands down.

Cost of failure/repairs - I honestly reckon my arc welder could last a lifetime, there's so little to go wrong. Not so with a MIG! e.g. new motors, linings, PCBs, etc, etc. Arc wins easily

Cost of MIG wire vs Arc rods. Weight for weight I think steel in an arc rod is cheaper based on 5Kg packs vs typical MIG reel wire weights. Moreover, MIG seems to lay down what looks like an excess of metal which is then ground off, wasted and thrown away. The effective cost per inch of metal joined must be higher with a MIG, even before...

The cost of gas: zero cost for an arc welder but a huge cost for a MIG welder. They eat disposable bottles at about £10 a go. Pub bottles of CO2 are better but still far from free. Argon and argon mixes are expensive, too.

Arc welding MUST be lot cheaper!

 

[snowcat]

I cant remember the figures for cost over arc, but MIG is certainly much cheaper theres plenty of costings about on it, although Simon's point for a low end user is probably worth some merit, I pay £14 per 15KG of wire, torch liners etc are under a fiver, then add speed of production, and the ability to continuous weld, also plants are less power hungry, not so much now with inverters but certainly than A/C buxboxes or oiled cooled, decent Arc consumables are around double in cost per inch......Dressing back should not be an issue on a properly set MIG plant....., also I have plants that are 20/10/and 2 years old, been used extensively and never missed a beat, there robust and the technology is nothing new...... Little buxboxes will go wrong like everything else can...even oil cooled

Cost of gas, expensive for a home user, because of the rental, gas siting in a bottle unused etc.......but there are ways of avoiding rental.....

Initial setup can be cheep but then I run an inverters that cost as much as light industrial MIGs, theres level entry into all markets even TIG......

As iv said all process have there uses, I use Arc more than I use MIGS as its more the tool for heavy thick plate, however I will happily swap to a MIG when burning box section together or TIG if required.....

George I have to price daily!!!......

 

[scarecrow]

Also, for finishing a bead, got to disagree with Scarecrow , I'd keep the arc close for a second or two, then pull away. Lengthening the arc increases the voltage, the amps stay the same, so more heat goes in, which isn't what you want.
.

thats me put back in my box I was doing some welding when I realise how I was finishing my runs was exactly as simondrains explained so I guess my hands know more about welding and my head