Multi pass MIG welding

[Spark plug]

Just wondering what the correct procedure for multi pass welding with MIG is?

For example for example how should a butt / fillet weld be executed on 20mm plate?

 

[davidjohnperry]

I will be interested to hear the answers to be honest ive been practicing this for a week I think for fillet weld its lay ur first run 50/50 base and wall then lay your second run on the bottom toe of the weld and then your third on the top toe of your first weld so both join in the middle. But im not used to this high amperage so im strugling. I could be wrong tho.

 

[Richard.]

You've just accurately described a 3 run fillet yes that is the sequence I'd do it in
For a 20mm butt weld I'd do it open root 1.5 gap and face, 60 degree inclusive. Root and hot then split it for filling up
Work in one direction only and it's always best if your last run is at the end not the middle of the joint.

 

[davidjohnperry]

I cant seem to get it correct yet im using 1/1.2mm wire im used to 0.8 so strugling to get it filled right xyz

 

[Richard.]

With regards to the fillet weld on 20 mm plate
If it is welded from both sides I'd do as above 3 run fillet
If it is welded from one side only I'd weld it in the form of a single bevel T joint