Rework - Bent Stainless Steel Tube

[greencircle]

Though I kind of given-up, but thought of bring it up here.

Have a arc shape bent Stainless Steel Tube. Overall arc length is about 2ft. ID=0.25in and OD=0.35in.
Is there a way to increase the ID by 0.03in. Have a about 100 such pieces to be reworked.

Can any one suggest a good way to do this.

Thanks in advance.

 

[MikeHalloran]

Fill them with water, plug the ends, and freeze them.
Try it on one or two first; you may not like the results.


Mike Halloran
Pembroke Pines, FL, USA

 

[berkshire]

One other way is sizing balls, The balls are graded in size and starting with the smallest are pushed through the tube, then when the biggest are in the tube, the smaller ones are inserted to push the bigger ones out, however. you may have a hard time pressing the number of balls you would need, through that length of tubing. Also being stainless you have the possibility of galling.
B.E.

You are judged not by what you know, but by what you can do.

 

[JStephen]

I can't imagine that either of those approaches would be practical. Go buy bigger tubing.

 

[greencircle]

I guess so, I should plan on scrapping it & get a larger tube.
Thanks guys.

 

[1gibson]

Well now that they're scrap, you might as well try out some of the suggestions.

 

[JStephen]

I remember reading of a battle in olden days where the losing side blamed their loss on the fact that they had 12-pounder cannons and 16-pound cannon balls, and therefore, it took an inordinate amount of time to load the cannons. I suspect that would be true of the tubing.

With the freezing-water suggestion, it should be fairly simple to look up the volume of ice versus water and see how much that expands- I don't think it's that much. The odds of that uniformly expanding the tube symmetrically, just the right amount, from end to end, seems fairly remote to me. If either idea did work, it would be a major amount of coldworking, and so the mechanical properties when it was all done might or might not suffice for the application.

 

[moltenmetal]

If they're already arc shaped and need that shape, sizing balls likely aren't going to help you.

The material costs peanuts, so the reason you're concerned must be the labour to make them "arc shaped".

 

[tbuelna]

Based on the OP the existing tube wall is .050" thick, and you want to increase the tube ID from .25" to .28". Depending on what other dimensions are acceptable for the reworked parts, you might have at least one option. You can chem mill .015" from the ID surface to get the .030" diameter increase. If you mask the OD surface this will leave you with a .035" wall after chem milling.

 

[greencircle]

@tbuelna thanks for your suggestion about Chem milling. Never heard or read about this process. I will google to learn more. Any link/article to this method is greatly appreciated. I would like to see if this is feasible solution.

If this is much time consuming & expensive, I will consider scrapping and making new parts.