Re: Inexpensive 2 Piece Die for Aluminium Casting


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Posted by Rob Frink on March 25, 19100 at 07:09:28:

In Reply to: Inexpensive 2 Piece Die for Aluminium Casting posted by Ben Mann on March 24, 19100 at 00:43:37:

Hello Ben,

Consider the shell sand method that BPF touched on a bit. I'm very familiar with it.

It is made by Borden and their trade name is Techni-sand. It comes in different grain sizes to suit you application.

The idea is to build your tooling (patterns) so that it can be heated up to about 800F. This sand is resin coated whichs activates when it touches the hot tooling (pattern) It sets up nice and hard on the surface forming a shell around the pattern. You must use your imagination designing the patterns so they can be removed. The real beauty with this stuff is that it is fast to mold up. The mold making process only takes 30 secs or so. The longer you wait before dumping off the excess sand the thicker the shell becomes. Also the shells are VERY permeable. Mould gas pressure is minimum which really helps out when pouring a light weight material like aluminum. Ther is very little pour off fumes and the castings shake out nicely.

I've learned that this technique "shell-sand" was developed by Nazi Germany in WWII and was only discovered after the war when the country was dissambled by the allies. I'm confident that you have it in Australia.

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