Techniques for casting from additively fabricated molds and related systems and methods
According to some aspects, a method is provided of casting an object from a mold, the method comprising obtaining a mold comprising a hollow shell of rigid material, the material comprising a thermoset polymer having a plurality of pores formed therein, providing a metal and/or ceramic slurry into an interior of the mold, exposing at least part of the mold to a low pressure environment so that a net flow of gas is produced from the interior of the mold into the low pressure environment. According to some aspects, a method of forming a porous mold is provided. According to some aspects, a photocurable liquid composition is provided, comprising a liquid photopolymer resin, particles of a solid material, in an amount between 30% and 60% by volume of the composition, and a water-soluble liquid.
1. A method of casting an object from a mold, the method comprising:
obtaining a mold comprising a hollow shell of rigid material, the rigid material comprising a thermoset polymer and one or more additives dispersed within the thermoset polymer,
removing at least some of the one or more additives from the hollow shell, thereby producing a plurality of pores forming an open cell network therein;
providing a metal and/or ceramic slurry into an interior of the mold; and
exposing at least part of the mold to a low pressure environment so that a net flow of gas is produced from the interior of the mold into the low pressure environment through the plurality of pores.
2. The method of claim 1 , wherein a mean size of the plurality of pores is between 20 μm and 100 μm.
3. The method of claim 2 , wherein the mean size of the plurality of pores is between 40 μm and 60 μm.
4. The method of claim 1 , wherein said exposing at least part of the mold to a low pressure environment comprises disposing the at least part of the mold in a chamber and lowering an air pressure within the chamber.
5. The method of claim 4 , wherein the air pressure is lowered to below 0.1 atm.
6. The method of claim 4 , wherein the mold includes a sprue portion, and wherein disposing the at least part of the mold in a chamber comprises enclosing portions of the mold other than the sprue portion inside the chamber such that the sprue portion extends from inside to outside of the chamber and forms a pressure seal between the sprue portion and the chamber.
7. The method of claim 6 , wherein providing the metal and/or ceramic slurry into the interior of the mold comprises providing the slurry through the sprue portion into the portions of the mold other than the sprue portion.
8. The method of claim 1 , wherein the thermoset polymer is an acrylic.
9. The method of claim 1 , wherein the mold comprises a plurality of ribs formed on its exterior surface.
10. The method of claim 1 , wherein the hollow shell has a thickness between 0.5 mm and 0.8 mm.
11. The method of claim 1 , further comprising removing from the interior of the mold an object formed from the metal and/or ceramic slurry.