aluminum mold

[rampa room artillery]

any thoughts on making a zinc projectile mold out of aluminum ??

rick bryan

[Double D]

any thoughts on making a zinc projectile mold out of aluminum ??

rick bryan

Yes,  Aluminum is a crappy material for  lead bullet mould it will be worse for zinc which has a higher melting point closer to aluminum melting temperature.

[GGaskill]

I don't think an aluminum mould would last very long casting zinc.

[Winger Ed.]

Something ya don't hear much about, but might work, and be halfway fun:

If you already have the Alum. mold, or can make one, you can use it to cast wax mold projectiles.
Then, use them as molds for sand casting your Zinc projectiles useing the 'lost wax' method.

It'd take a little research, and a bit of set up expense for the correct wax & sand, but it might be a viable atlernative     

[rampa room artillery]

well, i have a 50 cal bullet mold made out of aluminum that i have been using for years and had no problem.    I have a 26 in stick of 6 in round aluminum i was thinking about turning out a new mold for my 2.25 mountain rifle.  ,and there is a 450 F degree difference in melting temp from aluminum to zinc. 
rick bryan

[MR.GADGET]

Rick, how about making some 1" molds, you should be able to get 2-4 balls per mold. Also make some GB size molds.

[GGaskill]

there is a 450 F degree difference in melting temp from aluminum to zinc.

That is true but Al loses strength as it approaches its melting point.  This is a quote from one source: "Most aluminum alloys lose strength at elevated temperatures, although some retain significant strength to 500°F."  source: http://www.steelforge.com/nonferrous/aluminum.htm

Another quote: "The 7xxx series of age-hardenable alloys that are based on the Al-Zn-Mg-Cu system develop the highest room-temperature tensile properties of any aluminum alloys produced from conventionally cast ingots. However, the strength of these alloys declines rapidly if they are exposed to elevated temperatures due mainly to coarsening of the fine precipitates on which the alloys depend for their strength. Alloys of the 2xxx series such as 2014 and 2024 perform better above these temperatures but are not normally used for elevated-temperature applications." source: http://www.keytometals.com/Article23.htm

Since zinc alloys melt around 715-735°F, and the actual temperature of molten zinc is likely at least a little higher, I would not expect aluminum moulds to produce good product very long.

[little seacoast]

Tried casting  zinc in a 2.20" aluminum mold last month.  I only cast a half dozen balls @ 780 degrees but managed to warp the mold slightly.  Buy steel.

[rampa room artillery]

what was the wall thickness of mold?? 

[Double D]

Rick,

Tell me, why don't you want to make this mould out of steel?

[rampa room artillery]

 I am going to use steel for some molds, i was just trying to find somthing to do with this aluminum i have. maybe a mortar sense there is so little pressure build up, and i can use alot of windage to keep pressure down.  or just a ornamental peice. 

  rick bryan

[Double D]

Use it for projectiles.

Mortars do have pressure and aluminum is not a suitable materiel for cannons or mortars.