# Mould size?



## sena (May 13, 2012)

Hi,
what would be the mould size for pouring 10 kg and 5 kg copper bar ? . 
can we use mould made out of iron plates ?
starting trial run tomorrow on tilting furnace 20kg capacity .
Regards
Sena


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## Geo (May 13, 2012)

if you use steel, i would lubricate the inside of the mold with soot (like the black carbon from acetylene) it should make the ingots more shiny and keep the copper from welding to the steel.


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## goldsilverpro (May 13, 2012)

With a cheap paint brush, apply a thin but thorough coating of motor oil to a warm cast iron mold before pouring - no puddles.


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## FrugalRefiner (May 13, 2012)

Sena,

If you're making your own molds the dimensions are totally up to you. 

First, calculate the cubic area you'll need. The density of copper is 8.96. We'll round that to 9 to make things easy. So each cubic centimeter (1 cm x 1 cm x 1 cm) weighs 9 grams. For a 10 kilogram ingot, you'll need 10,000 / 9 = 1,111 cubic centimeters. So, just as a rough starting point, a 10 cm x 10 cm x 10 cm mold would be 1,000 cubic centimeters, a little smaller than needed for a 10 kilo ingot.

From there you can just play with some numbers. Cut the thickness in half to 5 cm, and make the length 20 cm. 5 x 10 x 20 = 1,000 cc. Make it a little longer, say 22 cm and you'd have 5 x 10 x 20 = 1,200 cc. That would be just about right, allowing a bit of extra so the pour doesn't overflow the mold. Adjust the numbers to suit your desires.

Don't forget to provide a slight angle, or draft, on the sides so the ingot dumps right out and doesn't get wedged into the mold.

Half that for a 5 kilo mold.

Hope that helps.

Dave


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