cold laps !

[SiPMerlin150]

I seem to be having a persistant problem of cold laps along the edges of my welds and its bugging me. I've stopped weaving (vertical down) normally weave a tiny continuous 'S' shape. Now I've reverted to just running straight down. It seems that running down quicker will sometimes reduce cold lap, ( one inch every two seconds travel rate).

Am I simply causing this undercut by not traveling quick enough, allowing the metal to sit on to of the parent material? I want to produce the best welds I possibly can.

 

[TechnicAl]

cold laps or undercut

to be honest vertical down with MIG is very very prone to lack of fusion

 

[SiPMerlin150]

The edges of the weld are stood up like a tiny step, sometimes your can see ( If you look very close with a good light) the edge is separated from the parent metal.

 

[Wendelspanswick]

With vertical down gravity can pull the molten weld pool down over the parent metal resulting in poor fusion. I always found that vertical up with pauses results in a stronger weld.

 

[Jim_gsxr1000]

I'm fairly new to mig and don't fully trust my ability with it at the moment, I'd be tempted to use stick for anything vertical at the moment

 

[matt1978]

The method for Vertical Mig and vertical MMA are very simerla. Its the Xmas tree or Triangle weave. If you can do it on one process the learning curve for the other should be pretty small.

 

[Jim_gsxr1000]

Yeh getting there with it, just more of a trust issue with the mig I still tend to use stick for important welds

 

[Burdekin]

The method for Vertical Mig and vertical MMA are very simerla. Its the Xmas tree or Triangle weave. If you can do it on one process the learning curve for the other should be pretty small.

Yep that's the way I was taught as well but with a root run straight up first and then the upside down triangle weave upwards. A slight pause at the bottom of each triangle. Hope I'm not telling you how to suck eggs.

The old boilermakers workshop foreman use to tell me there was no such weld position as vertical down. Give vertical up a try unless there is some reason you need to do vertical down.

 

[SiPMerlin150]

I'd be happy to do it in stick, but its all MIG and has to be all downwards welding... If that's what they want, its their orders I guess. Another thing, he tells me not to weave as it will spread the puddle out too far, and he showed me how he wants it doing, and looks to be a straight down run. He's a bit of a perfectionist...

 

[Hitch]

What thickness is it you are having trouble with?
Personally, i think down isn't great for anything thicker than about 3mm.

 

[SiPMerlin150]

3mm onto 6mm, Hitch

 

[Rrunnach]

You mean "overlap"?

 

[SiPMerlin150]

You mean "overlap"?

Cold lap, the edges look to stand proud of the parent material a tiny amount.

 

[SiPMerlin150]

Well, today has been a more productive day, The welds have look much better. Traveling a little quicker reduced a build up of metal that simply isn't hot enough to sink into the parent metal. Needless to say, I got onto a good MIG set and stuck with it all day. Supervisor cam along and had a good inspection, and said he is more than satisfied with my work and opened the option of overtime for me (more money, yay!) Money aside, I'm more than happy with my welds being to their standards than the extra pay.