Originally Posted by
dang
Hi,
Currently, I do Aluminum Gravity Die Castings in my backyard. Basically, I make a steel die on my mini mill. This die is built out of several different pieces of steel. After it's cut, I then polish the die to a mirror like shine and weld those pieces together.
When the die is finished, I melt the aluminum and simply pour it into the die. Gravity does the rest. The die is clamped together with simple screw clamps. I also use sand cores. The actual solidification of the Alum takes about a minute inside of the die. The surface detail is really good.
This is for larger parts.
Knowing what I know now, I'd do a few things differently.
1st I'd use Graphite for the actual mold structure. It's easy to cut. Waaay easier than steel is. I've seen people use a freakin Dremel to cut the stuff. It's permanent. It'll take the heat.
2nd, I'd cast using Zinc or Zamak instead of Aluminum. Especially for smaller parts which are mass produced. It has a lower melting point than Alum does, it requires about 2/3 of the energy expenditure to melt, and can deliver many of the same features. At least for non critical parts or those that don't require low weight and high strength. Oh, and if the mold is to be clamped shut, you'll find that the smaller die casting machines (200 ton and under), ONLY use Zinc. Aluminum is hotter and requires more force to keep the clamps shut tight. I believe that this high clamping pressure is so the machine can handle very large parts or molds. Also, repeatability and reliability is a big concern.