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Flaring SS hydraulic tubing

Gobo

Titanium
Joined
Jun 4, 2013
Location
Oregon, USA
We are trying to put a 37 degree JIC flare on SS tubing and are experiencing cracking at the flare. We have tried 304 and 316 with no luck. I know this sounds dumb, but bare with me. We have been told that it cannot be done, but our engineers don't believe it, so we cant give up yet. Is anyone doing this successfully, and if so , what is the secret. Oh yeah, .75 diameter tubing. Even seamless tubing cracks.
 
Well, I've done hundreds of such flares with no problems. AS mentioned, the flaring tool must be for stainless. The floor mounted, motor driven flaring machine we used for all critical work used a highly polished off-center cone that orbited as it plunged into the tubing. The orbit and depth of plunge were set according to scales on the machine.

For hand use, we used the Imperial Rol-Air. It uses a centered cone that incorporates 3 tapered rollers that spin around and gently ease the flare outward one roller at a time.No other tools were approved for NASA work.

4-F 37deg Rol-Air™ Flaring Tools - Imperial Tools

Dennis
 
We are trying to put a 37 degree JIC flare on SS tubing and are experiencing cracking at the flare. We have tried 304 and 316 with no luck. I know this sounds dumb, but bare with me. We have been told that it cannot be done, but our engineers don't believe it, so we cant give up yet. Is anyone doing this successfully, and if so , what is the secret. Oh yeah, .75 diameter tubing. Even seamless tubing cracks.
As mixdenny said, you need a tool which flares with only line contact. Rigid makes an oscillating cone flaring tool for plumbing, model 454-w and 455. It has a replaceable cone and has a feed and burnish setting. Can't consider this a production tool but you can use it for proof of concept. I've been successful with 1/2" hard copper and 1/4" 300 series stainless.
 
Well, I've done hundreds of such flares with no problems. AS mentioned, the flaring tool must be for stainless. The floor mounted, motor driven flaring machine we used for all critical work used a highly polished off-center cone that orbited as it plunged into the tubing. The orbit and depth of plunge were set according to scales on the machine.

For hand use, we used the Imperial Rol-Air. It uses a centered cone that incorporates 3 tapered rollers that spin around and gently ease the flare outward one roller at a time.No other tools were approved for NASA work.

4-F 37deg Rol-Air™ Flaring Tools - Imperial Tools

Dennis

I have done thousands of flares using the Imperial Eastman flaring tool. I had a bit of trouble with cracking with one lot of tubing, the supplier replaced it with material from a different lot. He scrapped everything from that lot. Never cracked another tube. make sure you lubricate the rollers or you will ruin the tool. It comes with a tapered reem to remove the burr left by the tubing cutter. TURN IT CLOCKWISE ONLY or you will chip the cutting edge and it will be ruined. McMaster Carr has them. Part number 2690A12, are you sitting down? 455.38!!! Yes you get what you pay for.
 
Did a bunch of JIC flares in 1/2" ss rigid tube for my boat steering, didn't have a problem. I think I went to the McMaster catalog looking for tubing, they said what spec could be flared, then shopped around for that spec. I was just using a manual flaring tool.
 
Wheel-type tubing cutter severely work-hardens the end of the tube. I would try a chop-saw. Get a very square, smooth cut. Leave no nicks from de-burring. Try annealing: heat to dull red and quench, do NOT slow-cool. Are you buying annealed tubing?
 
I deal mostly with sub .25" stainless tubing and for production forming (flares, tapers, closed ends) it is all done on rotary swaging equipment. It's amazing the forming that can be done without cracking. If you are doing several hundred or more, I would look for someone that can rotary swage.
 
Wheel-type tubing cutter severely work-hardens the end of the tube. I would try a chop-saw. Get a very square, smooth cut. Leave no nicks from de-burring. Try annealing: heat to dull red and quench, do NOT slow-cool. Are you buying annealed tubing?
We have tried heat treating without quenching. We will try with a quench. Oil or water?
 
Another point, - when you ream the burr out, only remove the burr don't countersink the end of the tube, .....it leaves an even thinner wall which will crack / split etc at the drop of a hat.
 
Just a update on how we are doing all the steps here with these tubes. We are working with .049 and .065 wall tubes here in multiple diameters but most of our volume is in the 3/4" x .049 tube. The other sizes don't seem to be giving us too big of a problem. We are making at least 500 flares per day as well. We are cutting them on a Baleigh chop saw with a Tiger saw attachment for measuring lengths. We are cutting them with a blade that is designed for stainless tubing. We are working on getting the rpm of the saw into the perfect range for the pitch count. We are cutting at around 50rpm currently. Then we debur them on a Tools for Bending rotary machine. This machine has adjustable knives that debur the inside/outside and put a light face on the end of the tube. Then we blow foam balls thru them to clean them out, bend tubes thru our tube bender, then flaring them with a rotary flare on another Tools for Bending machine.
 
Gobo,

From your last post it becomes obvious yours isn't a backyard shade-tree kind of operation, but with all the 'tools for bending' machines, why haven't you folks commiserated with them on your problem. It seems like flaring and tubing are their mainstay.

Stuart
 
Atomarc- Good observation. FYI I started this post but the guy who is actually in charge of this project wrote the post right before yours, so it might be getting a bit scattered. But yes, we are an OEM and do tens of millions of dollars in business every year. We just recently switched to stainless tubing and are still learning. We have all the resources we need, its just a matter of getting the correct information and putting it all together. I think " Tools for Bending " is actually the name of the company we are purchasing product from.
 








 
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