Stich Welding 2

[ER_Azza]

HI All

Need your opinion. I am no welding expert.

I am trying to weld a small shield plate (3mm) (non-structural) to a frame.
However, I am concern with the potential warping of the thin plate.
Thinking of doing stitch welding to mitigate this (as opposed to full perimeter weld), but I am concern with it susceptibility to corrosion, and as well as poor fusion.
And stitch welding itself could potentially does not mitigate warping due to localize heating.

Thanks

 

[MintJulep]

I suggest small screws into tapped holes, with a sealant on the faying surfaces to address your stated concerns.

 

[ER_Azza]

Thanks mate, but I did not draw my sketch with enough info.
Can't screw tap a screw as there is not enough thickness on the frame.

 

[DVWE]

What’s the application? Does it have to be welded? What about adhesive bonding?

The devil is in the details; she also wears prada.

 

[ER_Azza]

HI DVWE

Yes it has to be welded. Adhesive bonding won't be strong enough for this application.
The plate is to act as dust shield.

I wonder if a full weld but staggered heat input will mitigate this warping.
Or any other option apart from stitch welding?

 

[MintJulep]

If you can use two "L" shaped plates then spot welding is possible.

 

[DVWE]

Your best bet for welding, intermittent (stitch) or not, is to clamp the thin plate onto a much thicker plate which acts as a heat sink. Welding should be as fast and as low heat input as possible to still get a sound weld. Leave on the clamps after welding until the part is completely cooled.

The devil is in the details; she also wears prada.

 

[kingnero]

What is the size of the 3 mm plate?
How much warping is acceptable?
How strong do you need the connection to be?

 

[LittleInch]

Pop rivets?



Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[dvd]

weld leg = 3mm
rule-of-thumb weld length, 4 x weld leg + 6mm (1/4") = 4 x 3mm + 6mm = 18mm

Just try it on a sample piece and adjust as required. (maybe preheat the thicker plate)

 

[3DDave]

Silver solder is the best option.

 

[kingnero]

weld leg = 3mm

You're in GTAW territory there...
I'd use GMAW for production purposes, and rather choose a low carbon steel in order to avoid preheating because it's very time consuming...

 

[Tmoose]

How many do you have to make?
Like others asked, how much distortion is allowable ?
What is the service environment, and the resulting corrosion concerns ?

Some hints on controlling weld distortion from the (late?) great Omer W. Blodgett here-

https://www.aisc.org/globalassets/modern-steel/steelwise/steelwise-february-2013.pdf

The stresses in welds from cooling are not removed by a large strongback.

From your mostly un-dimensioned image I expect the thin dust shield will curl up several mm.

From your description so far I'd consider welding a few stout tabs with tapped holes to the "frame".
Then bolt the dust shield to the frame tabs.

Treat the faying surfaces appropriately before assembly.
Galvanized paint, RTV, etc.

 

[MintJulep]

3DDave's suggestion to brazee is very good.

 

[dik]

Check with Masterbond... they have some pretty good adhesives. You might be surprised.

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[dvd]

Use a plate thicker than 3mm if warping becomes a problem.

 

[TugboatEng]

Cutting slots and plug welding from the outside will drastically reduce warping vs fillets on the inside. Shrinkage will be in the same plane as the plate.

Edit: had an autocorrect error. This comment should make much more sense now.

Also, plug welding is much easier to do from a manufacturing standpoint.

 

[btrueblood]

Was going to reply with what Tug said, and can only add - you could still add a few tacks on the backside if the front plug welds caused some warping. How many and where located are why you get an experienced welder to do the job.