Aluminum body panels for 69 Camaro

[tyoneal]

Originally Posted by 68TT396

I have been wanting these for a very long time. Aluminum body panels when done right will work even better than steel. If this were not so then all our fighter aircraft would be made with steel skins.

Let me start by saying I have 13 years of experience working on US Air Force fighter aircraft in the repair & fabrication area.

Every fighter aircraft skin is made from aluminum, titanium or some form of composite. We make most of the skins from 2024 or 7075 grade aluminum. They are all installed with flush mount removable fasteners or with panel adhesive & flush mount rivets. The exotic materials are typically only used for radar tracking reasons and in high heat areas that would melt aluminum.

For the building of complex shapes like our fenders the material needs to be weldable so the higher strength 2024 & 7075 can not be used. We need to switch to 5052 or 6061 in an un-heat treated condition so they don't crack during forming. After they are formed the product needs to be annealed to remove the stresses put into the panel during forming then it needs to be heat treated.

An after fabrication heat treated 6061-T6 formed panel will be extremely tough to dent but if you do manage to dent it then it is as simple as lightly heating the area with a rosebud torch until the area returns to its as-heat treated shape. As long as the area is not too badly damaged (like a sharp crease) the light heating will bring the panel back into shape.

If these new aluminum fenders were dented from people knocking on the top surface then they were made from un-heat treated material and never annealed and heat treated as they need to be.

Another thing that needs to be done is to increase the panel thickness a little. From the photos it looks pretty close to the same thickness material that the stock steel panels are made from. This just won't work. The material needs to be about 50% thicker than steel to have the same dent resistance after it is heat treated. If it is un-heat treated and the same thickness as the steel counterpart it will dent if somebody even looks at it funny. This is probably what the Cobra's & early 60's light weight cars used, un-heat treated low strength aluminum that formed easily. It would explain why they all dent so easily and couldn't handle people leaning on them. We walk all over our fighter aircraft with no fear of denting the panels.

Aluminum body panels can be made to be very durable and light weight at a fraction of the cost of carbon fiber. They will be more expensive than steel but should not be $4000 for a front clip. I can see a 50% upcharge for the material change and heat treatment so a front clip should be in the $2000 range.

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To All:

This Post is Spot on. I worked in the Aerospace Industry a number of Years, and Aluminum Panels when properly Engineered, Formed, and Annealed and or Heat Treated are very stable, light and strong.

The Heat Treating and the annealing is the key to working with Aluminum. Plus Aluminum has a lower melting point making it easier to Anneal, Heat Treat, Acid Dip, Work harden etc.

It's all in the Technique used as to what your out come will be. I built numerous panel for the F-16 (Fort Worth, Texas) And Aluminum also stands up to many types of forming Techniques. You can hammer, draw, stretch draw, hydra-form and Hand work, etc. etc. Aluminum. The Key is getting it soft enough to be worked,(Annealed), then Harden it to make it strong.(Heat Treating) You also need a place to properly quench it.

If you have large panels, many times it is how the panel is engineered as to whether is has the strength necessary for a specific task.

Like anything else, understanding the material, and engineering around the weaknesses that you have to live with, will be your key to success with it.

Aluminum is a really cool metal to work with whether pressing or machining, and it comes in a variety of different types. You can also make tools and Die sets for it out with cast-able epoxy, so having a Foundry, die grinders and the expense and safety issues associated with it are not necessary. A DROP HAMMER die for 125/1000's Aluminum, forming a part with concave, convex and tight radiuses, can be formed off a checked piece in about 10-14 days, and that includes any stepped heat curing of the epoxy.

If you have never seen a Pneumatic Drop Hammer Machine Operate, it is really amazing how tough properly prepared epoxies can be, and they work like a charm with Aluminum, so it allows smaller shops the ability to construct parts that would normally not be able to due to lack of proper equipment. (This is the case in many Prototype Shops Around the Country)

Anyway, long story short Aluminum is a terrific material to construct high performance pieces out of.

Thanks for your patience's during this semi dissertation.

Regards,

Ty

[JamesJ]

I am all for it... Whatever anyone wants to do is cool... Just not for me and what i want...

[preston]

Thanks for the information guys. Is there an explanation of the kind of heat treat we could do at home ? I assume you need a large enough oven. I know true heat treating is a pretty meticulous process.

Also, back to applying epoxy so we can do body filler. There has been some talk about using powder coat as a pre-paint application instead, and I know powder coat would stick to aluminum. Would that be an effective method ie powdercoat the panel, rough it up, and then start on the bodywork ?

ANd for that matter, Powder coating would be a controlled 400 degree bake. Would this add any strength back into the material ?

I have built some big TransAm/DTM wheel flares out of .05 5052 which is probably too thin, but with the flanges and such that were added its reasonably strong. I never annealed it but I did obviously tig weld it along the entire seam. Its not OEM strong and I dont' expect them to be but I would like to think they won't just disintegrate on track at speed !

[dave96dcm]

There is some really good info in this post, it's cool to see new stuff that is being made. I have a few friends with E46 (2001 - 2006) M3's and they have Aluminum hoods, and they don't have any dents, and I know at least one of them was in a small wreck on the side of the car, and they did not need to replace the hood but the core support is out of wack a little and you need to push pretty hard on his hood to get it to close and there is no dent at all.

[CraigMorrison]

Originally Posted by BThibodeaux

Or how bout just runnin a big F'in motor that don't know the difference between +-200lbs.?

You'll then need to add a few sacks of concrete mix in the trunk to balance out the car.

[68TT396]

Originally Posted by tyoneal

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Aluminum is a really cool metal to work with whether pressing or machining, and it comes in a variety of different types. You can also make tools and Die sets for it out with cast-able epoxy, so having a Foundry, die grinders and the expense and safety issues associated with it are not necessary. A DROP HAMMER die for 125/1000's Aluminum, forming a part with concave, convex and tight radiuses, can be formed off a checked piece in about 10-14 days, and that includes any stepped heat curing of the epoxy.

If you have never seen a Pneumatic Drop Hammer Machine Operate, it is really amazing how tough properly prepared epoxies can be, and they work like a charm with Aluminum, so it allows smaller shops the ability to construct parts that would normally not be able to due to lack of proper equipment. (This is the case in many Prototype Shops Around the Country)

Anyway, long story short Aluminum is a terrific material to construct high performance pieces out of.

Thanks for your patience's during this semi dissertation.

Regards,

Ty

OK, who do we know that can do an epoxy mold drop hammer production run of cowl hoods, trunk lids & cowl panels for us? These would be a great starting point as they will fit all first gen Camaro's. The year specific parts like doors, fenders, header & valance panels and bumpers can come later after the process is ironed out and gets some popularity.

Bumpers and their mount brackets might be an easy first step in doing this for somebody interested even though they are year specific.

On A-body cars this could save a ton of weight putting on aluminum bumpers & mount brackets. They could even be chrome plated to look completely stock.

[tyoneal]

Originally Posted by 68TT396

OK, who do we know that can do an epoxy mold drop hammer production run of cowl hoods, trunk lids & cowl panels for us? These would be a great starting point as they will fit all first gen Camaro's. The year specific parts like doors, fenders, header & valance panels and bumpers can come later after the process is ironed out and gets some popularity.

Bumpers and their mount brackets might be an easy first step in doing this for somebody interested even though they are year specific.

On A-body cars this could save a ton of weight putting on aluminum bumpers & mount brackets. They could even be chrome plated to look completely stock.

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I'll quickly run through some of the steps necessary to make parts off of plastic die sets. It won't be complete, because it is late and I'm tired, but it should be close enough to give you an idea.

First
1) How big is your production run?
2) A complete hood would be pushing the limits of a Hammer forming press because of size, however some of the larger presses might be able to do something that large.
3) The process of making any of these is very methodical, but easy if you don't get in a hurry.
First Get a good part to make your dies from. Take the good part and put a releasing agent on it. Usually paste wax will due

Off the part create:

a) A checking fixture (This fixture will be used as a reference as to the quality of the part being made. With this you will also use a template to scribe your newly formed parts. The scribing will also show where to drill registration holes. (Out side of the actual part surface) These holes will make sure the new part is on the checking fixture in the right place. The checking fixture will have dowels in it where the new piece is to be placed. once everything lines up and is checked for a tight fit, the part is trimmed along the scribed lines and is ready to be used. Sometimes due to material thickness variation or wear on the die set a part will fail when used on the checking fixture. In this case, hand forming (Tweeking) might have to take place to slightly modify part until it conforms acceptably to the checking fixture. Once it passes the trimming can be done.


b) A good reliable source for consistent material ( type, thickness, etc.) will need to be acquired.

c) Access to a the correct presses (many of these can probably be found for a song in the Detroit area (Many of these presses in the automotive or aerospace companies have been around since the 1940's), or any area where metal parts were formed for aircraft (or cars) when they were primarily aluminum. If nothing else many shops, especially prototype shops will do small runs (25 - 100 parts)

d) You make your die set out of a good quality part, surface coat (gel-coat) that was made for part production. These gel coats are enhanced with ceramic powder, (Alumina Oxide), iron powder, silicon carbide etc. depending on cost and how many parts you want to make) These extra ingredients add abrasion resistance to the surface so the dies will last a long time.

A wooden box will be made to support and surround the part while the pouring of the material is being done and the initial cure is taking place.

The die set is made 1/2 at a time. Once the gel coat is applied to the part and becomes tacky, pour in a very slow curing epoxy. In weights over 1 pound expect a cure time from 1 to 10 days, otherwise excessive heat will build up and ruin the die by causing excess shrinkage or even fire (If you have a moron as a chemist) This will need to be poured 6-12 inches thick depending on the shape of the part being made. The die will have to be larger than the part by 4-8 inches on all sides for strength and to allow the excess area of the part being made to have a place to be. Once this has cured, remove part from initial casting. and turn the first part of the die on it's back with the part side up. Wax the surface of the die half as a releasing agent. Then place sheet wax (Melting point over 150 degrees) instead of the original part of the same thickness of the part, where the original part used to sit.

Carefully brush on the gel coat over the entire surface making sure to relieve all radiuses of any air pockets. (Brushing in one direction will usually work in this case) Once completed and the gel coat is tacky pour in another batch of the properly mixed epoxy compound. Again let cure depending on the amount and size of the part.

Once initial cure has taken place, take a hardness test of the epoxy. it should read 75-80 on a shore "D", Durometer. If possible at this point, slide into an oven at 100 degrees for 3-6 hours. Raise temp to 125 degrees for 3-6 more hours, and finally to 150 degrees for 3-6 final hours. Once die set has come back to room temp (25 C/77 F) Take another hardness reading. it should have hardened up into the 85 to 92 range on the durometer. This will depend on what was used as an elastomer (sp) in the plastic. (This gives the epoxy it's impact resistance. usually it is type of pour-able rubber compound that takes the brittleness out of the cured plastic. ATBN is a common compound used in hammer formed dies)

At this point separate the die set and machine off the back sides until each half is level. Mount each half onto a piece of plate steel as to give a very solid foundation to the plastic die set, and something that can be used to mount the die in the hammer press.

You can start making your initial parts at this point.

I'll writie more is you have some questions. I'm pooped right now.

Take care,

Ty