Tube bending tips required

Normally you would not try to cold work a heat treatable Al alloy in the T6 condition. At that strength level buckling defects (ripples) will be very hard to avoid. 6061 is usually worked in a softer condition and heat treated last.

Dave Korzekwa

Well yes, I've heard of it and even tried it with little success. I think it depends on the ductility of the material being bent.

Original Message:

Still trying to chase the perfect bend in high tensile, thin wall aluminium tube (6061 T6). Using an 8" fixed former and a section bar pressed by a lever and bearings I can get OK bends. I see bends done with no rippling on the inside and wonder how?. Any bending gurus out there. The bends are for an ultralight tailplane (No the Ultralight boys don't know squat) and the bends are acceptable as is I would love to get them perfect or close.

DIY

Reply:

Check rec.crafts.metalworking as there has been some recent discussion about this. A google search of the group yields a ton of posts.

AW

I have heard of sand used. Supposedly Wood's Metal works even better (Wood's Metal is a bismuth alloy with an extremely low (158°F) melting point, so it can be melted in hot water). 6061-T6 tubing is tough to bend, though..... if possible it might be better to get some in "0" temper and heat treat it afterwards if necessary. More commonly 5052 alloy is used if it is to be bent (a lot of paramotors use 5052 for the frames).

-Dana

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Good point, The ductility of 6061 T6 tube is not good. At a tensile strength of 30000 PSI and work hardening as it bends!!!!!!. As I mentioned, sand didn't help, as a matter of fact made the ripples worse. Someone out there has a "Gem" of a tip to conclude this subject, I know it!!.

DIY

I suggest you get a copy of:

Piping handbook, Crocker and King, ISBN 07-013841-9, McGraw-Hill

I have the Fifth edition and Chapter 7 is "Manufacture, Fabrication and Joining of Commercial Pipe". However, on page 7-129 the topic is "Bending of Aluminum and Aluminum Alloys" and discusses minimum bending radius including formulae for various alloy of aluminum (and 6061-T6). This handbook may answer all of your fabrication questions (sand filling too).

Good luck, Jim Y

CAREFUL with sand . It has to be absolutely dry. In other words cook it before you put it in the tube. Seal the tube at each end and you'll get a great smooth bend, my experience with steel only. If there is any moisture is the sand it turns to steam when being heated and you have a great pipe bomb ready to go off in your face. Rod

I suggest you get a copy of:

Piping handbook, Crocker and King, ISBN 07-013841-9, McGraw-Hill

I have the Fifth edition and Chapter 7 is "Manufacture, Fabrication and Joining of Commercial Pipe". However, on page 7-129 the topic is "Bending of Aluminum and Aluminum Alloys" and discusses minimum bending radius including formulae for various alloy of aluminum (and 6061-T6). This handbook may answer all of your fabrication questions (sand filling too).

Good luck, Jim Y

I submitted this earlier, but have not seen it posted. I apologize if it posts twice.

I suggest you get a copy of:

Piping handbook, Crocker and King, ISBN 07-013841-9, McGraw-Hill

I have the Fifth edition and Chapter 7 is "Manufacture, Fabrication and Joining of Commercial Pipe". However, on page 7-129 the topic is "Bending of Aluminum and Aluminum Alloys" and discusses minimum bending radius including formulae for various alloy of aluminum (and 6061-T6). This handbook may answer all of your fabrication questions (sand filling too).

Good luck, Jim Y