Bending AR400

[f150skidoo]

I'm doing a job that I need to bend 8 pieces of AR400 flat bar the easy way, the material is 2.5" wide x 5/8" thick and needs to bent to a 7.5" radius. My two thought processes to bend these is make a custom 5-6" die and bump bend the radius in my press brake. But being my brake is a simple hydro/mechanical press brake bump bending is a PITA to make repeatable bends. My second option that I'm leaning more towards is make a custom die for my hydraulic tube bender, which I feel will be easier and make more accurate bends in the AR steel. My main question is how much spring back should I expect from AR400. Should I make the die a 7" or 6.5" radius to get my desired finished radius with compensating with the spring back? I've provided a drawing of what the finished part is suppose to be.

 

[speed bump]

You need a lot of tonnage to bend 5/8 thick AR400. I would be surprised if your tubing bender can do it.

Is your press air over hydro or does it have some other way to limit tonnage to your bump?

 

[f150skidoo]

You need a lot of tonnage to bend 5/8 thick AR400. I would be surprised if your tubing bender can do it.

Is your press air over hydro or does it have some other way to limit tonnage to your bump?

Hmm you might be right on not having enough tonnage but it can bend 2" 3/16 wall tube, My brake has a limit switch to control the stroke

 

[speed bump]

Hmm you might be right on not having enough tonnage but it can bend 2" 3/16 wall tube, My brake has a limit switch to control the stroke

Rule of thumb I have heard is double your tonnage for AR plate. Any bending I would do with AR plate is farmed out so I can't give you a good answer to what it looks other than lots of tonnage. What are you trying to use this for and how many are you bending? If it's not many I bet having your steel supplier bend it for you is way cheaper than making a die.

I keep hoping 4 FN 27 would chime in as he has probably more experience bending plate than anyone.

 

[mike93lx]

Rule of thumb I have heard is double your tonnage for AR plate. Any bending I would do with AR plate is farmed out so I can't give you a good answer to what it looks other than lots of tonnage. What are you trying to use this for and how many are you bending? If it's not many I bet having your steel supplier bend it for you is way cheaper than making a die.

I keep hoping 4 FN 27 would chime in as he has probably more experience bending plate than anyone.

Add an @ symbol before a username to tag them and they'll get an alert.

@4 FN 27

 

[f150skidoo]

Rule of thumb I have heard is double your tonnage for AR plate. Any bending I would do with AR plate is farmed out so I can't give you a good answer to what it looks other than lots of tonnage. What are you trying to use this for and how many are you bending? If it's not many I bet having your steel supplier bend it for you is way cheaper than making a die.

I keep hoping 4 FN 27 would chime in as he has probably more experience bending plate than anyone.

I definitely should of had it outsourced, but the material is already sitting in my shop to make the 8 parts. If its double the tonnage of mild steel it will be 18 tons in a 5 inch die which isn't to bad. To make a die I would cnc plasma cut some 1/2" plate and laminate them together which isn't a big deal to make

 

[4 FN 27]

I'm doing a job that I need to bend 8 pieces of AR400 flat bar the easy way, the material is 2.5" wide x 5/8" thick and needs to bent to a 7.5" radius. My two thought processes to bend these is make a custom 5-6" die and bump bend the radius in my press brake. But being my brake is a simple hydro/mechanical press brake bump bending is a PITA to make repeatable bends. My second option that I'm leaning more towards is make a custom die for my hydraulic tube bender, which I feel will be easier and make more accurate bends in the AR steel. My main question is how much spring back should I expect from AR400. Should I make the die a 7" or 6.5" radius to get my desired finished radius with compensating with the spring back? I've provided a drawing of what the finished part is suppose to be.

I keep hoping 4 FN 27 would chime in as he has probably more experience bending plate than anyone.

I just rolled up to the house from the shop...got to the shop at 5:45 am this morning...

Hmmm? AR400? We have not done much AR400/AR500 other than laser flat work for one of the "big" Target Manufacturers.

The Tube Bender is not a bad idea but the spring back thing can be a real issue having to to make tooling over and over unless you can sleeve the die???

Me, I would bump it in the Press Brake. About 10-20 total hits using a 1.000-2.000 dia inch Punch. Eye ball or use a straight edge to guide the perpendicularity to the punch. Use a Sharpie and make hash marks for the hits unless you have a programmable back gage. With the back gage just program the bend lines and walk the part towards you. Problem is until you get the depth right (spring back) you keep making parts...or as the old times use to say back in the day: "Hand Jive them to print" by going back and keeping bumping it until it matches the profile.

The question is what size bottom? Might be a good option to made a bottom using a couple of pieces of Round Stock tack welded to a flat plate that rests on the bed of the Brake. That way you can break the tacks and move them in or out accordingly and re-tack.

Use some caution when forming "tough" materials. We have a couple of parts that require us to bend Manganese and this stuff eat tooling. I mean like every 10-12 hits the punch tip is gone and the tool needs to be replaced. The other issue is the material can fracture and when it does it can send pieces flying. AR400 is getting in that area where one might consider wearing a ballistic vest. We did have a guy take a piece of material to the chest not too long ago.

I would also polish/deburr the edges of the parts so they are less likely the craze on the bend lines.

New ground to cover for me...but this is how I would start. Hope it helps.

Looking forward to hearing what worked.

Edit:

Here is a good read on Bending AR Plate.

 

[f150skidoo]

I just rolled up to the house from the shop...got to the shop at 5:45 am this morning...

Hmmm? AR400? We have not done much AR400/AR500 other than laser flat work for one of the "big" Target Manufacturers.

The Tube Bender is not a bad idea but the spring back thing can be a real issue having to to make tooling over and over unless you can sleeve the die???

Me, I would bump it in the Press Brake. About 10-20 total hits using a 1.000-2.000 dia inch Punch. Eye ball or use a straight edge to guide the perpendicularity to the punch. Use a Sharpie and make hash marks for the hits unless you have a programmable back gage. With the back gage just program the bend lines and walk the part towards you. Problem is until you get the depth right (spring back) you keep making parts...or as the old times use to say back in the day: "Hand Jive them to print" by going back and keeping bumping it until it matches the profile.

The question is what size bottom? Might be a good option to made a bottom using a couple of pieces of Round Stock tack welded to a flat plate that rests on the bed of the Brake. That way you can break the tacks and move them in or out accordingly and re-tack.

Use some caution when forming "tough" materials. We have a couple of parts that require us to bend Manganese and this stuff eat tooling. I mean like every 10-12 hits the punch tip is gone and the tool needs to be replaced. The other issue is the material can fracture and when it does it can send pieces flying. AR400 is getting in that area where one might consider wearing a ballistic vest. We did have a guy take a piece of material to the chest not too long ago.

I would also polish/deburr the edges of the parts so they are less likely the craze on the bend lines.

New ground to cover for me...but this is how I would start. Hope it helps.

Looking forward to hearing what worked.

Edit:

Here is a good read on Bending AR Plate.

I appreciate all the info, I will take that all into consideration and will update the thread with what did or possibly didn't work.

 

[mike93lx]

does something like this have to be bent cold?

 

[speed bump]

I had forgot about this but SSAB has a decent guide for bending hardox (their AR brand name).

https://www.ssab.com/-/media/files/en/hardox/bending-guide-for-bending-hardox-wear-plate105en-2023.pdf?m=20230919124329

Apparently they also have a calculator that you can download to predict spring back.

 

[BD1]

5/8'' is pretty stout. I would get a price on having it done.

 

[MoonRise]

Per the ref article on linkedinand the SSAB article, you are in for a tough time bending that AR!

No pun intended.

Your tooling should be HARDER than the plate, so you are now looking at getting and making hardened tooling. From 4FN27's experience, the press tool only lasting 10-20 hits on some manganese steel is not looking good for tooling longevity on trying to press bend some AR400 plate. 8 pieces to bend at 10-20 hits to bump-bend each piece and you might be looking at using up 1-2 press tips per piece or 8-16 hardened steel press tips to do this one job.

From the ref article, for 5/8" AR plate your MINIMUM tool radius for the press brake should be 5x the plate thickness which works out to 3.125" tool radius MINIMUM.

Your V die MINIMUM recommended opening is 10x plate thickness which is 6.25" die opening MINIMUM. And recommended to have replaceable HARDENED round rods with a minimum 5/16" radius inset into the V die 'edges' for the AR plate to be pushed against.

Those are MINIMUM recommendations.

How are your already cut plate pieces oriented with regard to the rolling direction? For bending you want (NEED) the grain direction to be transverse to the bending direction.

You will NEED to grind and at least partially polish the cut edges of your plate and any surface scratches/gouges to reduce chances of cracking as you bend the plate.

And +99 on using PPE and shielding when trying to bend hardened steel. It can shatter and send shrapnel in an instant.

Spring-back on ~90degree bend on AR plate can be as high as ~ 15-25 degrees.

Can some 5/8" thick AR400 plate be bent? Yes. But it is not the same as bending mild steel.

Bending calculator from the Rolleri site:

BENDING RULES - CALCULATORS - Rolleri S.p.A.

Bending rule and rulers to calculate the tonnage of "U" profiles, "Z" profiles, flattened profiles and offset Z profiles.

www.rolleriusa.com

for 5/8" thick and 2.5" wide AR400, the calculator comes up with ~25 tons to bend your pieces to 90 degrees using a lower die with a 6.25" V opening.

 

[f150skidoo]

So a update on this job. I made a simple die up and made my first bend and quickly realized that this is going to be a massive headache to get the desired results. After contemplating on outsourcing it I ended up talking to the customer about slightly modifying the part that the ar400 gets welded to by getting rid of the radius and making it a 45 degree angle. Then all it would be is cutting the flat bar into 3 separate pieces and welding back together which he was fine with. Appreciate everyone's input in the thread.

 

[Fixr]

So a update on this job. I made a simple die up and made my first bend and quickly realized that this is going to be a massive headache to get the desired results. After contemplating on outsourcing it I ended up talking to the customer about slightly modifying the part that the ar400 gets welded to by getting rid of the radius and making it a 45 degree angle. Then all it would be is cutting the flat bar into 3 separate pieces and welding back together which he was fine with. Appreciate everyone's input in the thread.

Discretion is the better part of valor. Probably dodged a number of bullets there.

 

[tarbellb]

Nice pivot

You've fabricated some serious stuff on here, I was interested to see how this landed

Now it's time to build!