Plug welding - technique & advice.

[N2ae86]

Just looking some advice and experience from you guys.

In preparation for some sill repairs I am going to attempt I have been practicing plug welds as I don’t want to make a mess.


Popped some holes in an old car wing, placed a flattened piece of copper behind the hole and then attempted to weld a plug. I just couldn’t seem to do it neatly without having to blob weld on top of weld.

I am using 0.8 wire which I think is the issue? The welds to hot?

I have tried doing the thin metal technique with the same wire and setting and it came out nicely with a decent clean weld and what looks like good penetration.

Opinions greatly appreciated,

Thanks

James

 

[Engineer]

Firstly you wont be able to weld onto copper...........plug welds generally involve a punched hole through the upper panel, and weld made onto the panel below through the hole.

In most cases for neat plug welds, you will need to up the power setting and wire feed a little, and .8mm wire should work fine.

 

[rtbcomp]

I guess he was using the copper to support the weld as he was welding the steel.

 

[Sean]

small hole ramp up the power and down on the wire speed gets nice flat plugs that look like messy spots.

or bigger holes and start in the centre on the back plate and spiral out till you get the top plate which is more reliable and probably stronger it will need grinding back

you need to have the two bits of the flange clamped tight and nice and clean in there too

sorry no decent photo

 

[Springerdinger]

Have a look at the tutorial on the website.
As is said power up slightly and feed a little slower. The tutorial says hole the torch to the centre of the back part of the join and hold the torch there while the weld pool builds. The move out in increasing circles.

I found when plug welding verticaly to start slightly higher than centre.
Make sure both panels are clean and paint free or the plug weld can sink and look like an Aero..

You are welding the back part of the join to get penetration in the join. If you start near the edge of the hole you wont get penetration and it can erode the hole bigger.

Also move down the panel and miss some holes so that you dont build up too much heat and cause distortion.

hope this helps, im still a rookie but after doing a load of plugs im learning fast

 

[N2ae86]

Thanks for the responses guys – RTBComp was correct I was using the copper to support the weld as the hole goes through both panels.

Guessing it maybe easier for me to try and fill the hole on the bottom panel first, using the copper to support the weld, grind it flat and then lay the other sections over the top and then plug weld. At least that way I have a base to work from first when doing the plug weld.

So general view is that 0.8 wire is fine for this sort of work.

I love this forum – so much experience and advice. Everyday is a school day!

Cheers chaps!

 

[bigbadbugga]

Thanks for the responses guys – RTBComp was correct I was using the copper to support the weld as the hole goes through both panels.

Guessing it maybe easier for me to try and fill the hole on the bottom panel first, using the copper to support the weld, grind it flat and then lay the other sections over the top and then plug weld. At least that way I have a base to work from first when doing the plug weld.

So general view is that 0.8 wire is fine for this sort of work.

I love this forum – so much experience and advice. Everyday is a school day!

Cheers chaps!

There shouldn't be a hole in the bottom panel, only the top panel.

 

[gavuk]

There shouldn't be a hole in the bottom panel, only the top panel.

well spotted and quite correct .N2ae86 will find it much easier now

 

[N2ae86]

Yeah I get that ... but there is .... so suggestions on the best way to plug the hole on the base panel prior to plug welding the other panels to it?

 

[PaulMcElhinney]

http://www.youtube.com/watch?v=BsDxqb2p5OM

James,

Note how this guy starts outside the plug hole. His logic is that it takes a split second for the arc to reach full temperature. He then moves into the hole and does a circular weld, finishing off in the middle.

 

[Springerdinger]

Hi

Make sure the arc is strong with the back panel. experiment with hole size 7.5 to 6mm
start in the centre of the back panel when the weld pool builds spiral out.
For vertical plugs I start slightly nearer the top of the hole.

If you start to close to the edges of the hole before the weld pool is under way you will just blow away the the top sheet and the penetration will be weak.

Cheers hope this helps