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Re: determining sheetmetal bend allowances
Re: determining sheetmetal bend allowances -- CCR5600Design	Post Reply	Top of thread	Forum

Posted by: bazash ® 03/16/2007, 12:45:45 Author Profile eMail author Edit

k factors are proven within 0.1mm using an amada pressbrake have also a data sheet from amada and the bend allowance is the same for each one , so that proves these figures correct i use inventor and have now got astoundingly accurate components to these k factors copper 0.35 mild steel 0.44 (cr4/hr4) stainless steel 0.26 (304/316) aluminium 0.6 (1050+) for inside rads (amada tooling) 6mm vee=1mm rad 7mm vee=1.1mm rad 8mm vee=1.3mm rad 10mm vee=1.6mm rad 12mm vee=2mm rad 14mm vee=2.3mm rad 16mm vee=2.6mm rad 18mm vee=3mm raq 20mm vee=3.3mm rad 25mm vee=4mm rad 32mm vee=5mm rad 40mm vee=6.5mm rad 50mm vee=8mm rad 63mm vee=10mm rad Modified by Administrator at Fri, Mar 16, 2007, 12:54:18

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Re: determining sheetmetal bend allowances
Re: determining sheetmetal bend allowances -- CCR5600Design	Post Reply	Top of thread	Forum

Posted by: Kelly Bramble ® 02/22/2007, 09:45:29 Author Profile eMail author Edit

The equation that I have (Aerospace Industry) shows the bend allowance or "Set Back" as: DL = A + B -SB Where SB = 2(R + T) tan (alpha/2) - (.01743R + .0078T)Alpha Alpha = Number of degrees in Bend Angle SB is developed at the neutral axis of the material by the angle "Alpha".   Modified by Kelly Bramble at Thu, Feb 22, 2007, 09:47:29

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Re: Re: determining sheetmetal bend allowances
Re: Re: determining sheetmetal bend allowances -- Kelly Bramble	Post Reply	Top of thread	Forum

Posted by: ST ® 03/12/2007, 07:05:04 Author Profile eMail author Edit

Kelly hi; Something that makes me confused is the last Alpha in the formula, What is that doing? Does is not need a trigonometric function in front of it? Surely you don't just put 90 for 90 degrees..Or are there some brackets missing somewhere? Where SB = 2(R + T) tan (alpha/2) - (.01743R + .0078T)Alpha Thanks a lot. ST

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Re: Re: determining sheetmetal bend allowances
Re: Re: determining sheetmetal bend allowances -- Kelly Bramble	Post Reply	Top of thread	Forum

Posted by: CCR5600Design ® 02/22/2007, 12:26:59 Author Profile eMail author Edit

Kelly, That is a very helpful diagram. I am especially curious as to whether or not the 44% material thickness is consistent with different grades of material. You did not indicate what material this diagram represented. Is it aluminum? And if so, what grade? Randy, The 3003 was chosen SOLELY on price. Cheap is good! Thanks for your help, guys. Ron "What we need are more people who specialize in the impossible." - Theodore Roethke

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Re: Re: Re: determining sheetmetal bend allowances
Re: Re: Re: determining sheetmetal bend allowances -- CCR5600Design	Post Reply	Top of thread	Forum

Posted by: Kelly Bramble ® 02/22/2007, 15:08:45 Author Profile eMail author Edit

The equation is used for Stainless Steel, Steel Alloy, Nickel Alloy, Copper Alloy and Aluminum. In aerospace, end item edge tolerance are not supposed to be tighter than plus/minus .010". So, the slightly different formed lengths due to a different bend allowance characteristics works out to within the standard tolerances. If a tighter tolerance is required, then post forming manufacturing operations, such as, shearing maybe employed. Modified by Kelly Bramble at Thu, Feb 22, 2007, 15:19:34

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Re: Re: Re: Re: determining sheetmetal bend allowances
Re: Re: Re: Re: determining sheetmetal bend allowances -- Kelly Bramble	Post Reply	Top of thread	Forum

Posted by: CCR5600Design ® 02/23/2007, 00:29:59 Author Profile eMail author Edit

Kelly, Thanks for the clarification. And, yes, + or - 0.010" is WELL within our manufacturing tolerances so this formula should work just fine. Ron "What we need are more people who specialize in the impossible." - Theodore Roethke

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Re: determining sheetmetal bend allowances
Re: determining sheetmetal bend allowances -- CCR5600Design	Post Reply	Top of thread	Forum

Posted by: randykimball ® 02/21/2007, 17:20:13 Author Profile eMail author Edit

Wow, I just learned something. Most likely because I never needed the bend to be that accurate. I expect it is because the 3003 stretches more. I'm betting it will depend on the T grade of the aluminum, too. I'm wondering why you didn't use 5052, for my knowledge base. The wow is not because I actually learned something.... that happens every hour... but because it never occured to me that this would be the case. Please share the data when you find it.. of course you know you may need to work-up your own new formula for that one material by making a few test bends. With aluminum, it makes a big difference if you coin the material or not. If you have no luck get back hold of me. I have very good friends who have developed a CNC control for brake presses which is an excellent control and is selling well. They will very likely know this concept and are quite friendly and helpful. I can put you in touch, if need be. The worst suggestion of your lifetime may be the catalyst to the grandest idea of the century, never let suggestions go unsaid nor fail to listen to them. Modified by randykimball at Thu, Feb 22, 2007, 19:19:26

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Re: Re: determining sheetmetal bend allowances
Re: Re: determining sheetmetal bend allowances -- randykimball	Post Reply	Top of thread	Forum

Posted by: Kelly Bramble ® 02/22/2007, 15:11:50 Author Profile eMail author Edit

Randy, in aerospace, 6061-T651, 2024-T4 are the most common alloy's used. BTW, I didn't know one could hydrualically punch a hole with a die in thick steel rod/pipe. I envisioned severe bulging and general failure. Modified by Kelly Bramble at Thu, Feb 22, 2007, 15:18:54

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Re: Re: Re: determining sheetmetal bend allowances
Re: Re: Re: determining sheetmetal bend allowances -- Kelly Bramble	Post Reply	Top of thread	Forum

Posted by: randykimball ® 02/22/2007, 19:29:54 Author Profile eMail author Edit

Agreed, when in aerospace nearly all we used was 6061 & 2024 with the exception of an occasional 356 casting. The castings were, as I remember, always in a totally not structrual nor remotely critical application. ... such as the bumper on the bottom of a 747 tail section that would drag the ground [wear plate] if the crew got too agressive during lift-off... (at least I remember it that way, chances are I'm wrong... wink .. it has been known to happen) I, frankly, wasn't even aware of 3003, ... interesting how that can happen. The worst suggestion of your lifetime may be the catalyst to the grandest idea of the century, never let suggestions go unsaid nor fail to listen to them. Modified by randykimball at Thu, Feb 22, 2007, 19:32:00

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Re: Re: Re: Re: determining sheetmetal bend allowances
Re: Re: Re: Re: determining sheetmetal bend allowances -- randykimball	Post Reply	Top of thread	Forum

Posted by: Kelly Bramble ® 02/22/2007, 20:04:33 Author Profile eMail author Edit

I have never used stuff, I thought it was a marine grade at first, this is the information I have on it: Good corrosion resistance and moderate strength, however it is not heat treatable. Used for air ducts, drawn metal parts, mail boxes, food and chemical handling and other general sheet metal work. Good machinability, and strengthens when cold worked. Can be hot worked as well. Available in coil, plate, wire, tubing, bar, shapes and sheet sizes Sometimes used in hot forging, and can be annealed following cold working. Apparently, one can extrude it as well. Strength: Yield 5 - 25 ksi (10 - 195 MPa) depending on temper. Tensile is 16 - 29 ksi (110 - 205 MPa) Elongation 4 - 30 % based on 2" (50mm) section Brinnell Hardness 28 - 48+ There is nothing special about 3003. I don't think it would or should be used for anything requiring tight tolerances.... Seems to be very inexpensive... for aluminum. Modified by Kelly Bramble at Thu, Feb 22, 2007, 20:05:15

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Re: Re: Re: determining sheetmetal bend allowances
Re: Re: Re: determining sheetmetal bend allowances -- Kelly Bramble	Post Reply	Top of thread	Forum

Posted by: CCR5600Design ® 02/22/2007, 15:38:03 Author Profile eMail author Edit

Kelly, From the information I found on this hydraulic punch, holes and slots can be punched into material up to and including 5/8" thick steel plate, I-beams, channel and angles with no deforming. Apparently, the practice has been around for several years in the steelwork area(for buildings and such) and I simply was not aware such a tool existed. Ron "What we need are more people who specialize in the impossible." - Theodore Roethke

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