Hi All,
I am working on the design of a machine that will automate the investment casting process for small aluminum parts (ZA-8 alloy). From all the investment casting that I've done, I've always used a fairly large and tall sprue because I was pouring molten aluminum into a room temperature mold and I needed the weight of the molten sprue to ensure that the mold was filled completely before solidification (Investment powder that I'm using:
My question is, do you need a large sprue (if really any?) if you are pouring molten aluminum into a hot mold that is held at a temperature above the melting temperature of ZA-8? For example, if the mold was inside a furnace that was held at 800°F and then molten ZA-8 at 800°F was poured into the mold and allowed to sit for 5 minutes completely molten, would the mold fill completely? The furnace would have a fairly decent vacuum applied to prevent air bubbles and the need for venting. Could the sprue be kept very small so that it was truly just an entry point for the aluminum so that no extra material is needed unnecessarily? Intuition would tell me that if the aluminum is molten it should flow and fill the mold complete like water would but maybe I'm missing something...?
Any input would be greatly appreciated!
I am working on the design of a machine that will automate the investment casting process for small aluminum parts (ZA-8 alloy). From all the investment casting that I've done, I've always used a fairly large and tall sprue because I was pouring molten aluminum into a room temperature mold and I needed the weight of the molten sprue to ensure that the mold was filled completely before solidification (Investment powder that I'm using:
My question is, do you need a large sprue (if really any?) if you are pouring molten aluminum into a hot mold that is held at a temperature above the melting temperature of ZA-8? For example, if the mold was inside a furnace that was held at 800°F and then molten ZA-8 at 800°F was poured into the mold and allowed to sit for 5 minutes completely molten, would the mold fill completely? The furnace would have a fairly decent vacuum applied to prevent air bubbles and the need for venting. Could the sprue be kept very small so that it was truly just an entry point for the aluminum so that no extra material is needed unnecessarily? Intuition would tell me that if the aluminum is molten it should flow and fill the mold complete like water would but maybe I'm missing something...?
Any input would be greatly appreciated!
