bending 5083 plate.

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bending 5083 plate.


Post by hawkins79 »

Hi guys, just wondering if anyone has any experience bending 5083 plate in a brake press? If so do you know what size dies and blades are used? It is for a plate boat I am in the process of building. the material thickness is 4mm or .157". None of the local guys seem to be able to do it without it cracking/snapping? Oh yeah, im in Melbourne Australia. Cheers guys

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Re: bending 5083 plate.


Post by goatram »

Check this out ... end-radii/

Google Minimum Bend Radius for Aluminum Plate. I am thinking 5083 is close to our 5086. Some Things are not meant to be bent with out some annealing then re-tempering. Kevin has a thread some where here about bending 6061 Pipe. When I tried to bend 6061 I cracked it so I use 6063 now. :banghead:
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Re: bending 5083 plate.


Post by kmorin »

hawkins79, I'd suggest that a 4T radius be considered for this alloy. I know that's getting fairly round but it has been my experience with both 5086 in its harder aging treatments and 5083 that big soft bending dies help a great deal. In fact most shops won't have a 4T nose bar, or their lower dies will not tolerate that huge bar.

So, while I think this is a reasonable target, it's sure to make the shop raise their eyebrows. One last note, depending on the lower die's top edge sharpness or bull nose; the bottom of the sheet can be 'engaged' into the die's two upper edges. IN both 5052 and 5086 this can cause a tearing of the bend material where the back half, of the plate or sheet, cannot flow into the low die because its 'jammed' onto the tiny notches formed when the upper die edge is engaged as the top die begins to bring pressure.

So rounding AND lubricating would not be harmful, even though the average shop will not agree without serious volumes of good beer to provide sufficient incentive to the operators to go the extra mile.

(6061 pipe will bend very poorly in dies that are not lubricated, sanded to a fine finish which then allows the pipe to move in the die instead of the die grabbing and tearing the pipe apart during the bend.)

Harder sheet or plate alloys, like 5083, will tear in a similar manner when the bend material cannot flow into the shape of the bend. So rounding off the top of the lower die (very fine sanding only) and spraying cooking spray into the bending area are both helpful when using press brakes.

If possible bend across the short axis of the sheet/plate not down the length. This is the 'grain' strain crack event which is different in different alloys and aging treatments.

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Re: bending 5083 plate.


Post by kmorin »

I forgot to mention. One shop (here) does 'three shot bends' to use a 0.187"/3/16"/~4mm dia. top die, so he makes three bends per 90; about one to three T separating each. None of the bends has the full 90 degree change, but they're all close to 30deg and this translates to a larger 4 or even 5T bend when stretched out.

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Re: bending 5083 plate.


Post by welderbob »

For 3/16 5086/5083 we made our own top die. We took length of 1/2 x 4" flat bar and skipped welded a piece of 5/8" round bar to the edge. We push that into a 2" bottom die. We haven't had any cracking problems.

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Re: bending 5083 plate.


Post by speedboats »

For 5083 H321 the formula is punch radius = 2.5xT (where T is the thickness).

I use a 20mm diameter punch for 4mm. (d=2r=2(2.5x4)). Bit of high school algebra for you! For the die we use 70mm wide (have used a 40mm gap when things are close, like double 90* folds on trailer chassis rails and cross members. We only bend to 90*

I believe the bend radius grows significantly if you use H116 (heat temper), then r=4T

In the attached pictures the trailer chassis is folded from 4mm 5083H32 alloy.
P1030323.JPG (139.2 KiB) Viewed 9021 times
boat 099 [boat1].JPG
boat 099 [boat1].JPG (52.27 KiB) Viewed 9021 times
56withskipole2.jpg (66.59 KiB) Viewed 9021 times

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Re: bending 5083 plate.


Post by CTMD »


I'm probably too late to this party. But JPAC Engineering in Moorabbin bend over a 25mm bar and Pelagic boats out in Leongatha uses a 12mm bar. Either of which should be fine, especially at this time of year and I'm sure either would help you out if you gave them a call.
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Re: bending 5083 plate.


Post by Pelagic Boats »

Yes we use a 12mm round bar punch in a 65mm V-bolck die. seem to work great on 4mm 5083 of all tempers. 5mm on the other hand is a different story, we pressed a job not to long ago with a 25mm punch in a 90mm v-block and every bend cracked.

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