Metal casting your Project:
When looking into different materials to make your
project out of, consider metal castings. Metal parts
are much more durable than Plastic and the tooling can
be less costly. A typical Plastic Mold can be as much
as $30,000 to $50,000 whereas a Pattern for a Sand Cast
as little as $3,000. Aluminum, Zinc, Brass, Copper or
Alloys can be light weight and when polished looks good.
Casting is a process where you have a hollow mold of
your part and you pour hot semi-molten metal into it.
Wait for the mold to cure. Break open the mold and you
have your part. There are two costs to castings. There is
the cost of the mold and the cost to pour the mold.
Sand Casting: Is the least expensive way to cast parts.
Typically you have a wood pattern of your part made.
They put a sand-resin mix around the wood pattern.
When the mix hardens they take the pattern out leaving a
hollow mold in the sand mix. Then they pour molten metal
into the mold and bust up the sand after the metal cures,
leaving you the part. Parts I’ve seen made are Concrete
and Carpentry Tools, Waffle Irons, small Electric Motor
parts. Parts usually have a grainy texture, due to
the sand.
Diecasting: Is similar to Plastic Molding. You have a
Metal Mold made and you force molten metal into it.
It is faster then Sand Casting and you can get a better
finish along with thinner walls since the Mold is polished.
I was recently in a shop that was doing all sizes of parts
from V-8 Engines for GM to small parts for Coleman
camping stoves.
Investment Casting: Sometimes called Lost Wax casting.
You have a wax model of the part made then they cover
it in plaster. After it hardens they melt the wax out
and pour the hollow plaster mold with molten metal.
Its’ drawback is you have one shot with a wax model.
It if doesn’t pour right you make another model.
This is the way they do many Sculptures and Statues.
I saw a statue of Bob Gibson and Lou Brock done this way.
The same shop was also doing Gun parts. It is
relatively inexpensive.
Metal Cast parts are sturdy, stronger and more heat
resistant. When you are doing a short run it can be
a cost savings to the Inventor.

Rich Freese
Arch City Service
(www.invention-mfg.com)