Mazak

[KeithW]

List,
Has anyone useful references as to the casting of Mazak low temperature alloy?

[Tel]

Just what did you want to know Keith?

[KeithW]

Tel,
I'm looking into minimising porosity in the castings. As far as I can see this originates from the flux used when melting and/or from pouring at too high a temperature.
Therefore I would like to know what is considered the best flux, when it should be added and what is the most suitable temperature to pour and is there an easy way to judge this temperature? Written like this it seems a lot to ask!!!

[Alan]

Mazac is just a trade name.
We used zink-The same thing- for die casting little toy cars. We just stuck the ingots in the heating resovoir and nothing more is added.

later in my career i open cast a largish heatsink in an open silicon mould. also no problem.(not really advised)

The problem that i always avoided was to minimise any sectional change. loads of radius everywhere.

my last effort was to fill an empty baked bean tin full of the stuff for a boat anode (or cathode) loads of sinkage and a bit of porosity.

I think you need to expand on what you intend to do.
Alan

[jackrae]

I cannot recall where I read it but I'm sure dehydrated washing soda (Sodium Carbonate) which is a whitish powder material is used as a degasser for zink based compounds.
I believe it is puddled into the molten mix then either skimmed off of before the melt is poured or the melt is run out under some form of scum weir.
Perhaps this may jog someones memory
Jack

[KeithW]

Thanks for the replies to my query. I should explain that the question was put to me by a friend who is under the impression that being a model engineer I should know these things. His intention is to make small steam plants for model boats, and is looking into the feasibility of casting cylinders in Mazak, boring and shrinking in liners of precision brass tube of the order of 0.5inch bore. I gather he wants cylinders smaller than Stuart Turner model 10.
I'm coming to the conclusion he should suck it and see using sodium carbonate as a flux as described by Jackrae.
Keith

[jackrae]

A word of caution

The sodium carbonate must be fully dehydrated before adding to molten metal otherwise any contained water will quite literally cause a steam "explosion".
So if you get standard washing soda make sure it's baked fully dry (in the better halfs oven)oven then store in an air tight container - or better still rebake immediately before use (biscuits ?)

jack