Tube I.D. Machining
Tube I.D. Machining
(OP)
Hello everyone, this is my first post on engineering tips.com. What I have is mult length tubing (~ 20 ft long). The tubing has an O.D. of 1.220" (31 mm) and an I.D. of 0.709" (18 mm). I am using this product in trying to develop a tubular part that will be used in a torsional fatigue application. The tubing I have is 4140 seamless product. I machined (peeled) the O.D. to remove any surface defects and then manufactured my parts and tested them. Unfortunately, the fatigue fractures are initiating from the I.D. of the tubing. When I investigated further, I found that this tubing was hot rolled after it was made into a tube and, as a result, it has small surface I.D. fissures that go down to about 0.005" in depth. Therefore, what I would like to do is to find a company (and process) that can machine this I.D. in order to take the I.D. from an 18 mm to ~18.5 mm or something close to fit whatever tooling someone would have available. I have heard of a process called skiving but can't find a company that can do it in the sizes I need. If a company cannot do this operation in the 20 ft mult lengths I have, then I can machine the O.D. surface first and cut it into lengths that are close to 4 ft long. Thank you for the reply.





RE: Tube I.D. Machining
RE: Tube I.D. Machining
RE: Tube I.D. Machining
Another option could could be electropolishing.
RE: Tube I.D. Machining
You may have to gun drill, straighten and hone the ID then finish the OD.
Induction hardening the OD can provide a longer life product. We have made a torsion bar subjected to high loads, reverse twisting and high speed full rotation actuation. The material is 4340 Q&T to 30-32 RC Induction hardened with the case drawn at a specific temperature for maximum life.
Ed Danzer
www.danzcoinc.com
www.dehyds.com
RE: Tube I.D. Machining
RE: Tube I.D. Machining
RE: Tube I.D. Machining
Try deep drilling
http://ww
Best Regards
RE: Tube I.D. Machining
I have used welded tubing that was hot stretch reduced, and Drawn Over Mandrel (DOM) but it also has small surface I.D. fissures. I have also used as-welded tubing and this does have a good I.D. surface quality except for the region where the weld flash is scarfed off. However, I can't get welded tubing in carbon levels over 0.30%. Hence the reason for going to seamless.
RE: Tube I.D. Machining
Mike Halloran
Pembroke Pines, FL, USA
RE: Tube I.D. Machining
Thanks for the additional information about the tube manufacturing process. Tubes that have been drawn twice should not still have a defect. Having said that, yes, skiving is a method for improving the ID surface of the tubes, especially when combined in 1 tool with roller burnishing. Ecoroll makes such a device. Use the following link for more information:
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RE: Tube I.D. Machining
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RE: Tube I.D. Machining
I have experience in tubular suspension parts subject to torsional fatigue, and I have came across the exact same problem as you. We had to discard cold mandreled tubes because of too many defects and surface roughness at the ID that originated internal cracks.
Finally, we successfully decided to use precision welded tubes, as per DIN 2393. They have a more than necessary ID surface finish. Obviously, it is a more expensive material, but it is far cheaper than doing an ID finish, which is an overkill operation for the part, money wise.
Using this kind of tubes we never had again a failed test because of internally originated fatigue fractures.
Also I did some benchmarking, and all european automotive manufacturers used welded tubes for that application with no further ID finish. Some of the top-notch car manufacturers (for top performance, very expensive models) performed shot peening internally, but also on welded tubes.