Body Creasing

[Casey Jones]

Feb 15, 2012 3:32:37 GMT -5 Casey Jones said:

Drew158
It strengthens the metal. tho....if not done right it could be a downfall if you have never done it there are some very good videos on youtube about it. it gets very repetative and annoys the neighbors but can be well worth it.


--------------------------------------------------------------------------------

Engineerguy
it also makes your car look really cool


All4HimRacing
Here's my mechanical engineering explanation in case anyone wanted to know.

You guys are absolutely correct, it makes the car stronger by increasing the ridge strength, but more science happens than most guys realize. Steel at the molecular level has a lattice (grid) structure. When you bend the metal, it causes that lattice to break and deform. Cold working or work hardening generates many dislocations which pile up and entangle, which will prevent further movement of dislocations. This is why when bending a paper clip back and forth - it becomes hard to bend at the same point and will eventually break if you continue.

The grains in the metal also become elongated. This a permanent deformation so dislocations pile up and the strenghth goes up also. The larger grain boundary in the elongated strip also helps to stop the formation of further dislocations so that it becomes harder. The metal also becomes more brittle and is more liable to fracture as the number of dislocations goes up. So you can definitely go too far.
There you go if anyone wanted to know the science behind how it strengthens the metal of your car.

VITO324
^^^Whoa! I had no clue that much science was in Demolition Derby.



DeerAcresDemo
^^^ Well said, Good quick tutorial.



alienoutlaw
So what happens when u heat the metal up a little bit when your creasing does that do anything extra?


nharvey48
^ Removes strength

Engineerguy

Here's my mechanical engineering explanation in case anyone wanted to know.

You guys are absolutely correct, it makes the car stronger by increasing the ridge strength, but more science happens than most guys realize. Steel at the molecular level has a lattice (grid) structure. When you bend the metal, it causes that lattice to break and deform. Cold working or work hardening generates many dislocations which pile up and entangle, which will prevent further movement of dislocations. This is why when bending a paper clip back and forth - it becomes hard to bend at the same point and will eventually break if you continue.

The grains in the metal also become elongated. This a permanent deformation so dislocations pile up and the strenghth goes up also. The larger grain boundary in the elongated strip also helps to stop the formation of further dislocations so that it becomes harder. The metal also becomes more brittle and is more liable to fracture as the number of dislocations goes up. So you can definitely go too far.

There you go if anyone wanted to know the science behind how it strengthens the metal of your car.


I am a mechanical engineer from the U of I and this is correct.

DUCKY29
and for suggestion..ear protection possibly since you may be hammering for awhile. and take some breaks. my hands were numb after hammering for so long and i got a few blisters

keith926
i use a air hammer... very loud and earplugs is a must or your ears will ring for awhile lol

Krueggs81
I love when you hit bondo-man that sh!t can make a mess!


Matt Krueger
So to the engineers then what is better a hammer or air hammer? How do you know whats to much for the metal your working with?

Engineerguy
^^^ I am an engineer by no means mind you. However when you get the tin so thin it tears or it gets to hard and pops is a good time to quit.

You are correct. Once the metal gets thin or begins to tear, it is too late. So that being said, I would recommend using a hammer and not the air hammer as you should be able to better control your thickness.

To answer the other question about the heat. When you heat metal, heating up can be tricky and hot spots are typical... so you end up with the potential to cause a kink at the hottest spot and therefore not an even thickness. Also, if the metal in the car is tempered at all, you ruin the process by heating again. However, if you want to use heat to be in you favor the most, I suggest heating the fenders after its in the shape you want, then cool it quickly with water (stand back a little, HOT). This will cause the metal to shrink tight, thus hardening. That is how they make hardened metal, mostly.

[Casey Jones]

Feb 15, 2012 3:33:33 GMT -5 Casey Jones said:

AllOut69
In high school we were taught how to temper steel in welding class. example, a regular piece of whatever metal you want to image. like you explained kinda.. Get it 'red hot' then quench in water or oil, so its 'hardened', then get it a dark purple "not glowing orange" color and let it cool with out water, so it would then become "tempered". I wanna say i kinda remember tapping the piece on the gound? But maybe not. Some thing along the lines of how he explained it was, hardened steel is strong, but brittle, meaning it will snap, but if its tempered also, it will allow it to bend but still be hardened.....
Never looked it up but and im sure there is a better way of doing it with engineering measurements and gauges and stuff. I always wanted to temper the front frame rails on my trucks to a point a little after where the cage is welded on because im sure at the point where its not tempered, its brittle. and the different chemistry of metal is all wacked. and there is no efficient way of doing it besides some rose buds and some beer.

DeerAcresDemo
So ur sayiing that after u get it glowing orange put water on it n then uts hardened so wat haopens wen we do that to the frame?
Mat45
Might have to test that out on a smaller scale like a pop can or something.

DerbyJock

Just remember if you do that to a frame you take the chance of it snapping or even bending in a different place. Remember strengthening something weakens something else. Just like using a cradle with a pulley protector and a dp. You make it so it holds the front down and it bends somewhere else or snaps the trans.
Mat 45
im waiting for someone to to use that method mat, but with a tranny brace and a pipe cross member.. im curious to see where it would bend then?

Derbyjock

Idk I'm sure we will find out soon enough.

HCWT25

well i havent seen anyone with tranny braces yet.. and im not exactly sure but i have an idea with what will happen.
pb413

so your telling me in theory if i heat my frame rails and through water on them then heat again to the "purple color and let it cool my frame rails will be stronger?
Luddy15

Everyone is seems to be missing the point of pinching.The idea is not to try to make the molecular structure of the steel harder although it happens through the process. what you are trying to do is form strong lines or ribs to to help distribute the force into the stronger areas of the car like the roof pillar and welded door areas. It also helps control the way a panel folds making the number of lines,how tight the pinch,how well it's peened and the direction the lines travel more important than the how hard you can make the steel.
Isaacwalden

^ 'well said. since were getting on the topic of steel types... I have always wondered how one of the newer ford truck frames would hold up if you put it under an old iron body. The metal in MOST frames is made out of mild steel but in the last 5 years or so some auto makers have been incorperating over 5 diffrent types of metal in their cars. Ford or example has been puting boron in the steel for their truck frames, It is some realy tough stuff if you bend the frame in one of those trucks, theres a very good chance that your gettting a new frame because you cant add heat to the frame and since its so hard most frame racks cant even straighten it. The only thing that makes me hesitate is once this boron steel bends it wont take much longer before it cracks and your front or rear will go from straight to sky high real quick (how much it can handle before it happens idk).
MikeTravis26

i "heat treated" a honda last year on the rear, went through two derbies. but i expexted the rear would be like a peice of tin foil. idk if i was wrong or the metal became harder. (i did red hot dots all over, but lines where it was creased)

it was also my grandpas idea and said he used to do it to his cars. he ran for over 20 years so it might actually make a difference heating up the body.
Does anyone have a model number and brand of air hammer they have found to be good for creasing? What about the bit? Any info would be greatly appreciated.

[drphiluponya55xr]

Here's a pic of my first car I built and first crease job also still learning

[doinit729style]

Nice job for your first time man. It takes practice and time lol but it's worth it.

[drphiluponya55xr]

Feb 20, 2012 20:31:05 GMT -5 doinit729style said:

Nice job for your first time man. It takes practice and time lol but it's worth it.

Thanks lol

[bighoss40]

Dang nice job. Hows the forearm feeling?

[crownvic891]

this was part way through with my first time using an air hammer. still isnt done yet

[bighoss40]

Looking good Justin

[drphiluponya55xr]

I to used a air hammer lol

[DemolitionMissions]

Yea. Wish I had an air hammer. Doing all that pounding by hand kills the wrist by the end of the night.

[redneckracing12]

box vic quarters

[shadow]

anybody got pics of an old iron gm thats creased need ideas on how to do mine

[grinder]

[nh437]

I did my truck just to experiment how it would do it only took me a couple days with a ball peen hammer n sledge

[dugger88]

what are you useing on the air hammer to do tis .