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Is 16 Gauge 304 Stainless on a 16 Gauge Finger Brake possible?

j c

Aluminum
Joined
Dec 20, 2013
Location
Queens
I am looking to buy a box and pan finger brake, but most of them are 16 gauge mild steel rated. I'm going to be bending 16 gauge 304 stainless. The thing is, I'm only bending maximum 13 inches long. The brakes mostly come in 24" length @ 16 gauge. Will I be able to bend the 13 inch stainless since it's shorter than the full length? Are the fingers normally hardened on these machines? I'm wondering if the sharp edge will dent if I try the stainless. Thanks
 

ChipSplitter

Titanium
Joined
May 23, 2019
Location
Maybe
304 SS bends easier than mild steel IME. You'll be just fine.

Just because it's stainless doesn't mean it's better..........unless it's from billet. :D :D
 

dana gear

Hot Rolled
Joined
Feb 27, 2013
Location
Northern califorina, usa
I will be the sacrificial lamb here. on a American made Pexto/Wilcox, Chicago or any of the other overbuilt American finger brakes no problem, use caution on just about all of the imports. I know someone will pop up and say there bending 10 ga in there 16 ga rated import finger brake all day long ,I am just saying use caution when purchasing a import and using out of rated capability.
 

j c

Aluminum
Joined
Dec 20, 2013
Location
Queens
Thanks a lot. dana gear, is that because the fingers aren't hardened on the import machines?
 

j c

Aluminum
Joined
Dec 20, 2013
Location
Queens
So bending stainless is not the same as cutting? I know shears always say 16 ga mild steel, 12 gauge SS, or something like that. But you're saying on a brake, the gauge can be mild steel or stainless just the same?
 

ChipSplitter

Titanium
Joined
May 23, 2019
Location
Maybe
So bending stainless is not the same as cutting? I know shears always say 16 ga mild steel, 12 gauge SS, or something like that. But you're saying on a brake, the gauge can be mild steel or stainless just the same?


I can't speak as to the shearing part. But if you look up the minimum yield strength, hot-rolled mild steel is about 40 KSI as opposed to 304 SS which is 25-30 KSI.

That's why AR steels are so ungodly hard to bend, some grades are like 200 KSI...
eek.gif



Here is a helpful chart for calculating press brake tonnage: Press Brake Tonnage Calculator — Cincinnati Incorporated

It obviously won't be accurate for a box/pan brake, but it will give you a relative figure to work with. Compare the values between A-36 >51,000 PSI vs. SS and you'll see what I mean.
 

j c

Aluminum
Joined
Dec 20, 2013
Location
Queens
That's amazing, I didn't realize that. I'm thinking about when I cut stainless on the bandsaw or on the lathe, it's more difficult. But then when I think of a screw - the SS strips way faster than steel. Thanks, I'm glad to know it's a little easier to bend.
 

Mark Rand

Diamond
Joined
Jul 9, 2007
Location
UK Rugby Warwickshire
So bending stainless is not the same as cutting? I know shears always say 16 ga mild steel, 12 gauge SS, or something like that. But you're saying on a brake, the gauge can be mild steel or stainless just the same?


Think about it. 12 gauge is thicker than 16 gauge.

When sawing or turning stainless, it's very important to have a significant cutting rate or feed per rev. if the cutting rate or feed is too low, the part can work harden to the extent that it can be almost impossible to cut wit the tool at the same setting. HSS tools (saw blades, drills etc.) can be wiped out by this.
 

gary-sc

Aluminum
Joined
Aug 20, 2010
Location
Santa Cruz, CA USA
I was always under the impression stainless steel is approximately 25-30% harder to bend than mild steel. Not sure if 304 is an exception, but I have always down graded 2 gauges on the shear and the finger brakes when working with stainless. Maybe it's due to having to over bend more to compensate for the added spring back on stainless? The Cincinnati calculator in the link seems to agree with me.
 

Peter S

Diamond
Joined
May 6, 2002
Location
Auckland, New Zealand
So bending stainless is not the same as cutting? I know shears always say 16 ga mild steel, 12 gauge SS, or something like that. But you're saying on a brake, the gauge can be mild steel or stainless just the same?

I think you have that around the wrong way. As Mark says, 12 gauge is thicker than 16, and 304 is harder to shear in my opinion.

Bending, I don't know re. comparison of loads, but I doubt it will harm (mark) the fingers. What damages the fingers are idiots bending flat and round bar :mad5:

I don't think fingers are hardened. When people bend round bar etc. they leave round dents in the fingers :angry:.
 

gbent

Diamond
Joined
Mar 14, 2005
Location
Kansas
As long as you are folding the leaf by hand (assuming you aren't a heavyweight class powerlifter) you probably won't hurt the brake. If you think its to hard to pull, set the top leaf back another material thickness.
 

dana gear

Hot Rolled
Joined
Feb 27, 2013
Location
Northern califorina, usa
I was always under the impression stainless steel is approximately 25-30% harder to bend than mild steel. Not sure if 304 is an exception, but I have always down graded 2 gauges on the shear and the finger brakes when working with stainless. Maybe it's due to having to over bend more to compensate for the added spring back on stainless? The Cincinnati calculator in the link seems to agree with me.

You bet,all things being equal, ie, thickness, width, stainless does take more force to form.
Our Chicago and Cincinnati hydraulic press brakes have tonnage meters, all things equal stainless always exceeds mild steel.
 

ChipSplitter

Titanium
Joined
May 23, 2019
Location
Maybe
I was always under the impression stainless steel is approximately 25-30% harder to bend than mild steel. Not sure if 304 is an exception, but I have always down graded 2 gauges on the shear and the finger brakes when working with stainless. Maybe it's due to having to over bend more to compensate for the added spring back on stainless? The Cincinnati calculator in the link seems to agree with me.


With 304 at 25 KSI and MS at 40-50 KSI it should be pretty simple........

That said, if you're bending other SS grades the numbers all change.... 301 (75 KSI), 440 (65 KSI), 17-4 PH (110 KSI).

Cincinnati is finding an average to "cover their butts". The truth remains that 304 has one of the lowest yield strengths of all stainless steels, hence easier to form.
 

j c

Aluminum
Joined
Dec 20, 2013
Location
Queens
With 304 at 25 KSI and MS at 40-50 KSI it should be pretty simple........

That said, if you're bending other SS grades the numbers all change.... 301 (75 KSI), 440 (65 KSI), 17-4 PH (110 KSI).

Cincinnati is finding an average to "cover their butts". The truth remains that 304 has one of the lowest yield strengths of all stainless steels, hence easier to form.

Thanks for clarifying this. So the quick answer is: 304 SS is easier to bend than mild steel.

Yes sorry, I said 12 gauge SS before when I meant to say 20 or 22 Gauge, thanks.
 

j c

Aluminum
Joined
Dec 20, 2013
Location
Queens
I can't speak as to the shearing part. But if you look up the minimum yield strength, hot-rolled mild steel is about 40 KSI as opposed to 304 SS which is 25-30 KSI.

That's why AR steels are so ungodly hard to bend, some grades are like 200 KSI...
eek.gif



Here is a helpful chart for calculating press brake tonnage: Press Brake Tonnage Calculator — Cincinnati Incorporated

It obviously won't be accurate for a box/pan brake, but it will give you a relative figure to work with. Compare the values between A-36 >51,000 PSI vs. SS and you'll see what I mean.

On the Cincinnati Calculator it only says "stainless" and doesn't clarify what grade, so it's difficult to know if that is correct.
 

gary-sc

Aluminum
Joined
Aug 20, 2010
Location
Santa Cruz, CA USA
Thanks for clarifying this. So the quick answer is: 304 SS is easier to bend than mild steel.

Not trying to start an argument here but that that is a completely false statement.

I wouldn't want you to buy a brake thinking stainless is easier to bend the mild steel (what the machines are rated for). I don't have the greatest metallurgy knowledge, but from experience and documentation you have this backwards. Maybe it's the difference between minimum yield strength and tensile strength (normally my books and catalogs reference 304 at 85k yield strength)? Either way, I don't think that if most of your work is 16ga 304 you will be happy at all with a 16ga rated press. I have a very nice Gerver 24" finger brake(hardened and ground fingers on these) and I would not exceed it's spec by that much. We also have a Dreis and Krump 14ga x 48" that bends 16ga 304 fine, and as JC said with his Cinci press gauge, our Amada press brake gauge makes it pretty clear that 304 take additional tonnage.

Please checkout these links before you purchase your machine.

Article in the Fabricator, about mid way down the article, advises multiplying the tonnage by 1.4 for 304 stainless.
https://www.thefabricator.com/thefabricator/article/bending/the-4-
pillars-of-press-brake-tonnage-limits


Download for Wilson tools bending chart that recommends 150% increase in tonnage for stainless (what flavor isn't specified)
http://marketing.wilsontool.com/acton/ct/8311/p-0081/Bct/-/-/ct10_0/1?sid=TV2:icKipd3is
 
Last edited:

Bondo

Hot Rolled
Joined
May 14, 2011
Location
Bridgeton NJ
I have a 4' 16 ga tennsmith box and pan, and I have bend 16" long pieces of 12 ga 400 series stainless. It did not like it, I had a 3x gap to bend and I had a huge bar to bend it. I only did say 20 bends over a month. Still using it just fine 10 years later.


Sent from my SM-G960U using Tapatalk
 








 
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