Aluminum casting?

Question

We are working on a new aluminum fixture. It is basically an aluminum
spine with many 6061-T6 pins sticking out. Currently we drill the
holes inside the spine and hammer the 5/32" 6061-T6 pins inside. Is
there anyway to cast aluminum with many 6061-T6 pins embedded (they
will stick out after the casting)?

Thanks........... Ken


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Answer 1

I saw this question hanging around in the unanswered pile and thought i might spend a moment on it. If i understand you right you have an Al (unknown chem) spine with alloy t-6 6061 pins sticking out. To save time you wish to cast two types of aluminum at once (exothermic weld) together and form a shape. I can see a couple of problems right off first would be draft on the pins so each were not ripped off during mold removal. Casting mold material is second and bonding strength on the pin ends is third.
Also in mind is the fact that your installation procedure now of hammering in the pins must be labor intensive.
One of the things i wish i knew is what you are doing with this piece ( is it under rotational moment or is it a linear application) and how many per anum do you need. If this is a once cast piece one rule would apply if you need 12k per day that might make a bit of difference....Have you ever used ceramic molds ? If so make several with holes for the pins in the locations you need use the same pins you need with acid etched ends. If the projection of the pin is long enough a bond should occur at approx. 1220deg however as the pins are at room temp they need to be heated or just heat the entire mold to perhaps 50percent of yield then pour. let air cool do not quench and see what you might get. I have not actually done what you are trying .However i have done this with cast brass and malable iron pieces. Including railroad tracks at a broken joint. Exothermic welding has been around for centuries and Aluminum of any type should yield and bond as do other materials.

The hammering process that you use cold works the Al at the hole site and actually makes it stronger there than anywhere else. At 5/32" the pins are very small and you might try extracting one for tensile. T6 has a tensile of about 35-36k lbs/in sq and pulling the pin out with a strain indicator (scale) should not prove to hard a job...Application dynamics play a huge part in the design process I wish you the best on your investment with this piece .....Good luck from the E......

Answer 2

How long are the pins? have you considered casting the pins along with the rest of the part? or is that what you are asking, it sounds, like you are talking about loading pins into the mold and having the cast "spine" bond with them.
What casting process are you using, or are you even using a casting now, or is the "spine" currently rolled or extruded shapes?
As mentioned on RCM, the pins will no longer be T6 after casting, if you need the T6 temper the part will have to be heat treated.

Answer 3

Similar to the plaster answer.
You will need to sacrifice your mold for each unit made. Use a thin shelled mold with the pins sticking into it. Have it in a second fixture that will hold the other end of the pins.
Have you considered putting the holes in the part during the molding process? Don't drill them afterwards just pound in the pins.

Answer 4

Casting aluminum is one of the least expensive ways to make metallic objects and with a little clean up work and polishing, the results are stunning and shine like the wings of the old WWII bombers. Cast aluminum melts at a hot but relatively low temperature and is easy to "carve" after you cast it. http://www.secat.net/

Answer 5

this may be a splash extra complicated yet promises extra advantageous element than sand casting. lost wax casting investment or ceramic shell you'll be able to make molds to form the wax yet investment or ceramic shell are destroyed interior the approach

Answer 6

aluminum can be cast in plaster of pairs, you could make a mold that held the pins in place, then when you cast the aluminum they would be there.
casting aluminum is fun, but I only did it once.

Answer 7

Probably, - but they won't be 'T6` anymore.
'T6` is a temper. If your spec.s call for it, there's probably a reason.