Warping of metal in a kiln 2

[richard4556]

I have a piece of wire mesh 460mm x 290mm. It needs to be supported on a frame arrangement to stop it sagging when I place (light) things on it. The mesh will simply sit atop the frame, not actually be affixed mechanically to it.

Let's say the frame edge is 1/8" wide stainless steel angle, and the same angle is used inside of that outer frame so as to provide support for the middle part of the mesh.

Assume nothing is on top of the mesh. When the kiln is heated up to say 900C (red hot) will that frame warp? I imagine it won't if the heating is all over and even.

Is there ant literature that deals with this kind of issue?

Thanks.

 

[EdStainless]

If the heating and cooling was actually uniform then the only distortion would be from residual stresses in the metal. You could take care of that my first heating and cooling a few times.
But in reality the heating isn't uniform. There are variations ins metal thickness and stiffness, along with the effect of placing items on it (not the weight so much as the cold spots).
The best that you can hope for is some slight warping.

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Plymouth Tube

 

[racookpe1978]

At 900 C the frame may not distort from uneven heating, but residual stresses from welding and fabrication will begin to work their way out. Then cooling, reheating, cooling, reheating, cooling, reheating ... cycles.

More important, for any very light structural steel "frame" under even a light an external load is going to sag and droop at that high a temperature under its own weight.

 

[tomwalz]

What they said.

I have spent 30+ years working around that temperature and things move.

You can get rid of residual stress from manufacturing of the kiln furniture but you will always have uneven heating and cooling at some level.

I would think you could also expect, burning , flaking and buckling of the stainless steel with repeated cycling. At least that is that we see here.

I asked a similar question here a few years ago and the answer was mullite. We developed a reinforced mullite that works well as kiln furniture. If you want to try it let me know. I have some sample pieces I can send you.

Tom Walz
Carbide Processors

Thomas J. Walz
Carbide Processors, Inc.

http://www.carbideprocessors.com

Good engineering starts with a Grainger Catalog.