[rjr8009]

Hey guys, I'm trying to get great at thin gauge SS, have no problems with .045 or larger. Sometimes when i tack, itwill not mend, from any angle. When I run a bead, it can start decent and sometimes I can get 3/4 of a lap joint completed and then BAM, top plate starts getting eaten up and tear away. Obviously, my puddle goes crazy and just bleeds out however it wants and then it all goes to the scrap bin. I've tried different angles and amps from 20-50. The only thing I can think of (while writing this post) is that maybe my 3/32 tungsten is too large? I have access to 1/16 tungstens and gas lenses so if that doesn't solve the issue maybe one of yall have some golden input? Thanks!

[tungstendipper]

3/32 tungsten is fine. Speed up your travel speed, use more filler rod to cool the puddle, and back-off amps with your pedal.

[rjr8009]

I'm using a FUPA12 cup, probably should drop down to something 4-8

[cj737]

It’s not the cup at fault. Can you/do you use chill blocks? Can you use pulse on your machine? The angle should always be the same regardless of the thickness- as close to 90* as possible.

Stainless absorbs heat rapidly and dissipates it very slowly. Thinner material just can’t take the heat so you either artificially cool the area (chill blocks) or you have to weld shorter runs (or lower amps, pulse, etc).

[LtBadd]

When you go into the world of thin, everything thing that matters, as far as weld prep and weld technique matters even more.
As already suggested use chill blocks/backing, tight arc, torch angle...

[rjr8009]

I'm using a 1/4" piece of stainless as my chill block, which doesnt help. The only other plate I have access to is aluminum. I tried to get my company to purchase a 1/4" copper plate for that reason but it's the only thing they've told me no to ordering. My machine is bad ass but since Miller upcharges for pulse (should be free on a $7k machine), I'm kinda left to flintstoning it on the pedal. For 6-8" coupons, I cannot go any faster than my current travel speed. If I do, it just deteriorates the top plate even faster. I just switched down to a #4 cup and it was a tighter arc at 40 amps, however, after the first 2 inches the top plate started tearing

[LtBadd]

My machine is bad ass but since Miller upcharges for pulse (should be free on a $7k machine), I'm kinda left to flintstoning it on the pedal.

The aluminum is better then the stainless as a chill block.

What Miller machine are you using?

Can you post a photo of what you're welding?

[rjr8009]

top picture is my issue on .035, bottom is .045 gauge. Both lap joints, no puddle issues or plates tearing away at .045. Using Miller Syncrowave 250DX

[rjr8009]

They switched the images around at upload, but I'm sure you guys know what you're looking at

[Poland308]

What’s your amps? Looks like too low of amps or a long arc.

[cj737]

I'm using a 1/4" piece of stainless as my chill block, which doesnt help. This is actually hurting you, not at all helping. Use the aluminum block, it will be fine.

I just switched down to a #4 cup and it was a tighter arc at 40 amps, however, after the first 2 inches the top plate started tearing

40 amps for 0.035 stainless is pretty high in my experience. I’d be running between 22 and 27 amps all day long. I’d still hold a really tight arc and revert to an #8 or larger cup.

[LtBadd]

Also try tacking every few inches so the plates don't pull apart

[tweake]

imho the plate getting eaten is due to it pulling up off the bottom plate and then its like welding a thin edge.

chill blocks help, clamping it down helps. lots of small tacks.
also using pulse really helps.

to me, the beads look a bit big and possibly slow. up the travel speed a bit.

[Oscar]

The few times I tried stainless, I quickly figured out I needed a super tight arc length. So close, it's tough to maintain---that close. <0.050". Otherwise I would have the edges curl up and blow apart/away.

[rjr8009]

Ran at 27 amps, no puddle could form. Ran at 30 amps, barely got one going, too slow and difficult to control by the time the plate started eating away. FUPA#12, CFH 5-10 and 18-25, .035 filler rod with 3/32 thoriated tungsten. I'm out opf moves to make for the time being

[Poland308]

Your going to need a thumb wheel or a pedal. As the part warms up you need to back off the amps as you travel.

[tweake]

i think part of whats happening is your big cup is reducing the heat tint. so it looks less heat effected than it is.
up the amps until it make a puddle quickly, but up the travel speed.

tacks should be fusion tacks, ie no filler.
imho the weld should be far smaller than whats shown. i think filler size is good, just aim for smaller weld and run faster.
also play with tungsten angle. think small precise weld.

that is usually what stuffs me up, being able to run accurately and fast.

[cj737]

The tacks look like your torch distance is too long. They shuold be minute. Full pedal, tight, tight arc. 90*. If the material is 0.035, 27 amps should turn the material wet immediately.

Having said that, using 0.035 filler will cool that puddle promptly so you might need more amps. One trick to stainless is to use the filler to chill the puddle to prevent burn up and blow out.

[Poland308]

Side note. If that’s a SS with a mirror finish then it’s probably not a readily weldable grade.

[tweake]

Side note. If that’s a SS with a mirror finish then it’s probably not a readily weldable grade.

??? i do a little bit of 316 and 304 food grade weld on fittings, all of which are highly polished.

[Poland308]

High polish and mirrored SS are two very different things.

[tweake]

High polish and mirrored SS are two very different things.

are you sure?
i just looked up mirrored stainless steel it was 304 and 316.

[Toggatug]

Could it be that since the bottom sheet is clamped down the table it is transferring more heat away from itself compared to the top sheet which is exposed before the chill lock comes into effect?


I know from my braze and silver solder experience if I clamp something to the table the part needs more heat to the bottom sheet to get up to braze temp compared to the part of the joint that is not clamped.


So to sum up does anyone else think it's worth a shot propping the weld joint off table with2 Ally chill blocks and leaving say a 1/2" -3/4" gap to allow the stainless to heat the same way as be top sheet?

My two sense hopes it helps.

Sent from my S60 using Tapatalk

[Poland308]

High polish and mirrored SS are two very different things.

are you sure?
i just looked up mirrored stainless steel it was 304 and 316.

Yes I’m sure. Yes you are partially right you can get 304 and 316 and many other 300 series of mirrored SS. However there are several other versions that are common that are considered unweldable. Even the 300 series will give you lots of trouble due to the surface finish.