Kirkham Motorsports University Superplastic Forming Alloy Strength Demonstration

[David Kirkham]

Originally Posted by Don

David.......WOW , thanks for the chapter on Aluminum 101

It is Kirkham University after all

David

[Don]

David, another KMU question, progressing from from 101 to 201......

Basically, the reasons behind a forged aluminum product vs. machined, and the choice of aluminum, heat treat etc. Such as:

" Profil wheels are forged from 6061-T6 aluminum alloy; this aircraft-grade aluminum is heat treated for a higher yield strength than your typical aluminum wheel. This allows us to create stronger, more stable wheels, while maintaining a low weight. "

http://www.fikse.com/2010/profil.html

........thanks

[David Kirkham]

Originally Posted by Don

David, another KMU question, progressing from from 101 to 201......

Basically, the reasons behind a forged aluminum product vs. machined, and the choice of aluminum, heat treat etc. Such as:

" Profil wheels are forged from 6061-T6 aluminum alloy; this aircraft-grade aluminum is heat treated for a higher yield strength than your typical aluminum wheel. This allows us to create stronger, more stable wheels, while maintaining a low weight. "

http://www.fikse.com/2010/profil.html

........thanks

Forgings are used when grain structure is important. Aluminum is forged at around 800 degrees F (if I remember right) then squeezed in a hydraulic press. You need some 25 tons/square inch to make a good forging. As you can see, that is a tremendous amount of force. The press squeezes the hot, plastic aluminum into the shape of the die making it flow into the die. Curiously, if the temperature is too hot, the aluminum will literally crumble. It is quite interesting to actually see it happen in real life. As the aluminum flows throught the die, the grains tend to line up in the direction of the flow. Usually, (but not always!) the stresses the part sees in life are also in the direction of the flow and so the direction of the grain strengthens the part. Alloys that are typically forged are 6061, 6082, 7075. We have made parts in all these alloys.

Another advantage of a forged part is you don't need to remove so much material to make the part. A forging basically makes the part in the general shape you need. Many times all you have to do is drill some holes and machine a few surfaces and you have a usable part. There is a HUGE drawback, however. Dies are expensive to make. Dies are also expensive to set up. So, it only pays to make a die if you are sure you are not going to be changing anything. But, what do you do if you are into constant improvment--like Shingo? That is why over the years we have gotten away from forgings and gone to machining our parts straight from billet. If we have a better idea today, we don't want to wait until tomorrow (or next year like many companies) when we run out of forgings to implement a new, upgraded part into our proeduction. If we have a better idea today, we want to implement it TODAY.

I imagine, the quote above that 6061-T6 has a "higher yield strength than your typical aluminum wheel" is comparing 6061-T6 (forging alloy) to 356-T6 which is a casting alloy. There is no doubt 6061 T-6 is far stronger than 356-T6. Castings do have their advantages, like you can cast intricate shapes that are quite impossible to make with machining (think about the hollow water jackets in an engine block). However, the strength of 356-T6 is quite low and we really don't like using it for much of anything. As the years have gone by, we have eliminated almost all castings from our car. The only casting left is the differential housing now. Who knows, one day we might billet that too.

Happy to answer any questions, or go deeper if you want.

David

[Three Peaks]

David,

For a while when work was short in construction, I worked as a maintenance electrician at Sapa Profiles- a large producer of aluminum extrusions. We used mainly 6061 T6 from long log billets and huge presses for the extrusions. Some of the extrusions were quite large and some were also quite intricate.
The material requiring hardening after the extruding process went through a process called "Aging" or "Age Hardening" which brought the strength of the part up to it's potential. This was done at temperatures ranging from 350 degrees to start to 500-550 degrees to age and then a cool down to temper. Timing depended on the part shape, size, and required hardening.
I was told at the time that the aging process only "accelerated" the hardening process and natural aging of the 6061 would eventually create the same hardness over time but would take up to 1-2 years to create the same conditions.

Would an aging process like this work for your engine block to create the hardness in the center where the billet may be "soft?"

Your videos and information piques my curiosity and creates more questions than answers at times......

Bob

[Don]

David:

" .......Happy to answer any questions, or go deeper if you want. "

Thanks for the reply and info, had previously bought the Fiske Wheels for the Z06

[David Kirkham]

Originally Posted by Don

David:

" .......Happy to answer any questions, or go deeper if you want. "

Thanks for the reply and info, had previously bought the Fiske Wheels for the Z06

Happy to help!

David

[David Kirkham]

Originally Posted by Three Peaks

David,

Would an aging process like this work for your engine block to create the hardness in the center where the billet may be "soft?"

Your videos and information piques my curiosity and creates more questions than answers at times......

Bob

Yes, many times large parts are rough machined and then heat treated (and aged). Then, they are final machined to size.

Questions are good. As Shingo said, "We must ask why--five times."

David