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      08-16-2010, 07:22 PM   #1
808MGuy
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4000 ton vs 8000 ton forgings

Does it really make a difference in an automotive wheel application or is the 8000 ton number just cock waving? Is there a point of diminishing returns in an automotive wheel application? I know there have been discussions about this in the past but all you see is 8000 is stronger than 4000. Well, of course but my question is, does it really matter in this application.
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      08-17-2010, 10:56 AM   #2
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Nobody up to having a technical discussion or have the guys who really know a lot about this stuff left the forum?
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      08-17-2010, 11:44 AM   #3
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I posted a response earlier today, but it failed for some reason.

Short version:
8000 ton = more grain distortion = higher yield strength
Probably diminishing returns going from 4000 to 8000 tons.
Many people are willing to pay extra for the slightly higher strength.
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      08-17-2010, 11:48 AM   #4
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Not a complete answer but having an 8000ton forged wheel vs a 4000ton forged wheel does not necessarily make it stronger in all cases.

If the wheel design is exactly the same and the same exact amount of material is used then yes 8000ton would be stronger.

But if a company using 8000ton forgings decides to shave a lot of material off to make it super light then a 4000ton forged wheel using the proper amount of material can be stronger.
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      08-17-2010, 12:04 PM   #5
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Quote:
Originally Posted by m34jlp View Post
Not a complete answer but having an 8000ton forged wheel vs a 4000ton forged wheel does not necessarily make it stronger in all cases.

If the wheel design is exactly the same and the same exact amount of material is used then yes 8000ton would be stronger.

But if a company using 8000ton forgings decides to shave a lot of material off to make it super light then a 4000ton forged wheel using the proper amount of material can be stronger.
Okay, so 1 advantage of the 8000 ton forging is that they can use less material to achieve the desired strength thus resulting in less weight. That seems to coincide with what's available on the market. Most of the 8000 ton forged wheels are very light. If that's the case, it seems that they could all be designed for a common strength regardless of the forgings used. That would make the argument you commonly see of 8000 ton forged wheels being stronger not totally correct as it would be dependent on the actual wheel design.
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      08-17-2010, 12:19 PM   #6
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bingo...the 4000ton vs 8000ton is a lot in the marketing.

It is incorrect to say that a 4000ton forged wheel is stronger than an 8000ton forged wheel. There are many variables that come into play when designing a strong wheel. It isn't dependent on material only.
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      08-17-2010, 03:57 PM   #7
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Quote:
Originally Posted by Radiation Joe View Post
I posted a response earlier today, but it failed for some reason.

Short version:
8000 ton = more grain distortion = higher yield strength
Probably diminishing returns going from 4000 to 8000 tons.
Many people are willing to pay extra for the slightly higher strength.
Although I am not a forging expert I know a bit about it. I think I am going to disagree here. I'm certainly open to some proof though.

The general need for higher pressure forging machines is simply to forge larger parts from stronger materials. In the aluminum area there are many factors more important to the strength of the finished items than the forging pressure. Those include:
  • Alloy selection (new high strength aluminum alloys, e.g. K651 aluminum from Kobe Steel) can offer a whopping 40% strength advantage over more typical 6061.
  • Design: Design (as mentioned above) is way more important than forging pressure. Pushing the weight and material use very heavily will result in a weak wheel, nothing you can do about that.
  • Forging temperature: Can affect strength by a factor of 200%.
  • Heat treating: Most high strength aluminum forgings are heat treated post forging. Details of the process will greatly affect ultimate strength.
  • Forging vs. casting. Here material flow and grain alignment offers a significant strength advantage for a given design.
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      08-17-2010, 04:08 PM   #8
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oh yeah well my wheels are 10,000 ton forged [/endcockwave]

...but seriously, as stated above the higher tonage is used to allow more material to be removed to make the wheel lighter.
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      08-17-2010, 04:08 PM   #9
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Good info all around. The long and short of it is: it's complicated. No single factor determines the strength of a wheel, and most of the time, with each upgrade to the manufacturing process, there is a choice to go for an increase in strength, or a reduction in weight.

Design, as swamp noted, is very important, and without advanced engineering analysis, that's not something that can readily determined.

I am no metallurgist, but I deal with a lot of wheels of pretty much any production process imaginable, and other than the fact that forged > cast, it's extremely hard to generalize. And even then, some excellent cast wheels may end up serving better than poorly forged wheels.

So the 8000 ton *could* allow for a stronger wheel, but it does not guarantee it.
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      08-17-2010, 06:12 PM   #10
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Does anyone know if there is a spec as far as strength is concerned in any of the governing bodies. JWL, TUV or whatever. If there is, I would guess that most companies would just design for that spec regardless of what material is being used. Once the design strength is determined, they can then begin to play with other variables like weight.
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      08-17-2010, 06:26 PM   #11
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Quote:
Originally Posted by 808MGuy View Post
Does anyone know if there is a spec as far as strength is concerned in any of the governing bodies. JWL, TUV or whatever. If there is, I would guess that most companies would just design for that spec regardless of what material is being used. Once the design strength is determined, they can then begin to play with other variables like weight.
Crazy to say but I havent seen many forged wheels getting certified. Since they are usually custom fitments they would have to get each special order certified. In that respect cast wheels have the upper hand. Not because the forged arent as strong but because you know what you are getting. This is why cast wheels shouldnt be marketed as certified across the board if they are being altered (Forgestar). Once you alter anything on the wheel they certification is void (not the original design/offset).

If someone really tried, they could make a super light forged wheel that is very weak.

This is why most wheels (forged or cast) all weigh the same or very close to each other. When one sticks out becareful. If it isnt properly designed from the get go there can be problems.

Forged wheel companies make a safe design that lets them mill the backpad for specific offsets w/o risking a wheel failure. This leads to more weight.

Now with wheels like RAC. The wheel is built for a specific offset/size so they can play with weight reducing techniques and then have that specific wheel fitment certified since it wont be altered. This guarantees it is strong enough for your vehicle.

Hope that makes sense...I am in a hurry.
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      08-17-2010, 08:40 PM   #12
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anyone know how many ton forged the e46 m3 oem 19 is? it is heavy but damn i ran over pot holes all the time and no bend whatsoever.
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      08-17-2010, 10:22 PM   #13
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its not how many tons, its the manufacturing process that makes a wheel strong.
One forge wheel is not equal to the other, and sometimes even good cast wheels are better than a shitty forged wheel, like the shit that comes out of Miami.
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      08-17-2010, 10:41 PM   #14
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Quote:
Originally Posted by m34jlp View Post
Now with wheels like RAC. The wheel is built for a specific offset/size so they can play with weight reducing techniques and then have that specific wheel fitment certified since it wont be altered. This guarantees it is strong enough for your vehicle.

Hope that makes sense...I am in a hurry.
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      08-17-2010, 11:46 PM   #15
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Quote:
Originally Posted by FruitCake View Post
its not how many tons, its the manufacturing process that makes a wheel strong.
One forge wheel is not equal to the other, and sometimes even good cast wheels are better than a shitty forged wheel, like the shit that comes out of Miami.

You just cut down half of the USA forged wheel manufacturers. LoL!
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      08-17-2010, 11:58 PM   #16
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Quote:
Originally Posted by FruitCake View Post
its not how many tons, its the manufacturing process that makes a wheel strong.
One forge wheel is not equal to the other, and sometimes even good cast wheels are better than a shitty forged wheel, like the shit that comes out of Miami.
Agree except that 99% these Miami companies actually make their wheels in California.

Actually I guess you shouldve written the shit that comes out of California...?

Oh wait and these Miami companies buy their forgings from the same people that all the other US companies buy them from. So I guess you shouldve said all the shit that comes from the US...

Hell the 20x13 that ADV.1 uses comes from Alcoa. I think we can both agree those forgings are far better than most...?
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      08-18-2010, 12:00 AM   #17
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Quote:
Originally Posted by graider View Post
anyone know how many ton forged the e46 m3 oem 19 is? it is heavy but damn i ran over pot holes all the time and no bend whatsoever.
I think I read they were much more than 8000ton forged but I read that awhile ago so I could be very off.
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      08-19-2010, 10:56 AM   #18
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Based on this post

http://www.m3post.com/forums/showthread.php?t=421385

It appears wheel manufacturers do shoot for a predetermined strength and then lighten as much as possible. So it seems like nobody really tries to max out on strength since they probably all shoot for the same load rating. Like others have said here, this means that the whole 8000 > 4000 argument really makes no sense unless you compare the entire manufacturing process.

This was a good discussion that for once didn't end up in a pissing match between certain groups supporting different manufacturers. Thanks everyone for keeping it a purely technical discussion.
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      08-19-2010, 01:14 PM   #19
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Quote:
Originally Posted by 808MGuy View Post
Based on this post

http://www.m3post.com/forums/showthread.php?t=421385

It appears wheel manufacturers do shoot for a predetermined strength and then lighten as much as possible.
Everyone will design/engineer/test a but differently. There is no uniformity in this process. However, what PERFORMANCE wheel folks do in general is shoot to pass a certification with minimal weight. As you know there are not really than many true performance wheel manufacturers.
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      08-19-2010, 01:19 PM   #20
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Reading all these posts really makes me feel confident and glad of the RAC RG63 wheels I bought and am using.
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      08-19-2010, 01:50 PM   #21
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As a rule of thumb:

Life: If it looks too good to be true...Stay away

Wheels: If a forged/cast one piece 19x8.5 is 3lbs lighter than all other competitors you should probably stay away or do a lot of research before risking a failure.
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