Three-dimensional printed metal-casting molds and methods for making the same
Methods are disclosed of making metal casting molds and components thereof by the three-dimensional printing process in which an untreated sand is used as the build material and a polymer is used as a component of the binder that is printed onto the build material.
1. A binder comprising a composition including (a) a carrier in an amount that is in the range of 75 to 95 weight percent, (b) high fructose corn syrup in an amount that is in the range of 5 to 20 weight percent, (c) a humectant in an amount of greater than zero weight percent and no more than 3 weight percent, and (d) a surfactant in an amount of greater than zero weight percent and no more than 3 weight percent, wherein the particular amounts of (a), (b), (c), and (d) in the composition are selected to enable the binder to be selectively applied by jet printing onto a build powder in a three-dimensional printing process and to bind particles of the build powder together in selected areas of the build powder with sufficient strength to form a desired article and the surfactant is selected from the group consisting of 2-methoxyethanol, 2-butoxyethanol, silicone oil, sodium laurel sulfate, ethanol, and isopropyl alcohol.
2. The binder of claim 1 wherein the carrier is water.
3. The binder of claim 1 wherein the humectant is selected from the group consisting of diethylene glycol, ethylene glycol, propylene glycol, polypropylene glycol, and glycerol.
4. A method for making an article which is a metal casting mold or component for a metal casting mold comprising the steps of:
a) obtaining a representation of the article;
b) selecting an untreated sand as a build material;
c) selecting a binder comprising a composition including a carrier in an amount that is in the range of 75 to 95 weight percent, high fructose corn syrup in an amount that is in the range of 5 to 20 weight percent, a humectant in an amount of greater than zero weight percent and no more than 3 weight percent, and a surfactant in an amount of greater than zero weight percent and no more than 3 weight percent, wherein the particular amounts of the carrier, the high fructose corn syrup, the humectant, and the surfactant in the composition are selected to enable the binder to be selectively applied by jet printing onto a build powder in a three-dimensional printing process and to bind particles of the build powder together in selected areas of the build powder with sufficient strength to form a desired article and the surfactant is selected from the group consisting of 2-methoxyethanol, 2-butoxyethanol, silicone oil, sodium laurel sulfate, ethanol, and isopropyl alcohol;
d) using the representation of the article, the build material, and the binder to three dimensionally print the article;
wherein the article is adapted for being a metal-casting mold or a component of a metal casting mold.
5. The method of claim 4 , wherein the untreated sand is selected from the group consisting of silica sand, fused silica sand, lake sand, bank sand, pit sand, chromite sand, zircon sand, olivine sand, alumina sand, mullite sand, and synthetic sands and combinations thereof.