Warping due to heat-affected zone
Warping due to heat-affected zone
(OP)

I am looking into orbital-welding the shown stainless-steel part to an ss tube and some couplings. However, some colleagues have expressed concerns that the welding process will warp the tiny, tiny 2 micrometer restriction hole at the end, possibly closing it or making it too large. I have a hard time believing that it will warp significantly (the tolerance on the hole diameter is already 20%), but I how do I convince them of this (if I am right)?
It seems that bending or stretching of the part should have minimal effect. Diametrical shrinkage or swelling would, at worst, have the same effect on the hole as on the whole part, so unless it's in the 10s percents, it won't be noticeable. Not to mention that the heat has a long way and a lot of material to go from the welding site to the restriction hole. We could also reduce the diameter of the tube at the welding site (it's outer diameter is too large anyway). Is there anything missing or incorrect from my logic?





RE: Warping due to heat-affected zone
RE: Warping due to heat-affected zone
Here's an example of what such a weld would look like on similar parts:
RE: Warping due to heat-affected zone
I agree that it's a nonissue from experience with other microwelding applications, but I would struggle to provide objective references.
RE: Warping due to heat-affected zone
RE: Warping due to heat-affected zone
RE: Warping due to heat-affected zone
RE: Warping due to heat-affected zone
RE: Warping due to heat-affected zone
B.E.
You are judged not by what you know, but by what you can do.
RE: Warping due to heat-affected zone
Still, we are nonetheless interested in the end product, which is a very small flow of gas through the hole. We can measure it, and we can do it before and after welding. But, by the time we get this thing shipped from the other side of the world, then get it tested, then get it welded, then get it tested again, then do it all again with a heat sink, +/- bureaucracy and red tape, it will be a loong time. In the meantime, we have a half-assed "plan-b" which we know will work, but it's ugly. And I would like to avoid it, hence the question.
RE: Warping due to heat-affected zone
I'll wager that if the welding is done correctly you cold hold the end with a bare hand.
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P.E. Metallurgy, Plymouth Tube
RE: Warping due to heat-affected zone
Best regards - Al
RE: Warping due to heat-affected zone
RE: Warping due to heat-affected zone
Best regards - Al
RE: Warping due to heat-affected zone
With such a small diameter flow orifice, the biggest concern would seem to be slag from weld drop around the tube ID breaking loose and clogging the flow orifice.
RE: Warping due to heat-affected zone
RE: Warping due to heat-affected zone
RE: Warping due to heat-affected zone
RE: Warping due to heat-affected zone
Still a mighty small hole.
RE: Warping due to heat-affected zone
My notes
1 um =1 micrometer = .000039370078
2 um = .00007874
is this not correct ? this what Terry also calc.
RE: Warping due to heat-affected zone
One Possible Solution:
1. You can manufacture a fixture, kind of a go gauge for the 2 micrometer restriction hole (I can see tapered cavity on the right side which can hold the gauge).
2. Put this go gauge on, every time you do the orbital GTAW.
I guess this might solve your problem for the reduction in the hole size.
RE: Warping due to heat-affected zone
~ 80 millionths I'd say, not 8
them pesky decimals
RE: Warping due to heat-affected zone
RE: Warping due to heat-affected zone
I would be pissed to get one that had the wrong flow and be told 'but the hole looks to be the right size'.
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P.E. Metallurgy, Plymouth Tube
RE: Warping due to heat-affected zone
RE: Warping due to heat-affected zone
RE: Warping due to heat-affected zone
To completely eliminate the hole deformation need the part head with the hole immersion in water and to weld.