Methods and systems for the manufacture of layered three-dimensional forms

A method for manufacturing a three-dimensional metal casting mold, comprising:

• a) coating a plurality of individual sand particles that are substantially free of binder material with an activation agent;
• b) dispensing an organic activatable resin binder material through a print head over preselected portions of the sand particles that include the activation agent for contacting the activation agent, pursuant to which the dispensed binder material is contacted with the particles no earlier than when the binder material first contacts the activation agent;
• c) reacting at a temperature of about 20° C. to about 30° C. the binder material with the activation agent for at least partially hardening the binder material, crosslinking the binder material to itself, and coupling adjoining particles to each other with the binder material, for forming a layer of the three-dimensional metal casting mold;
• d) repeating the steps (a)-(c) to form the remainder of the three-dimensional metal casting mold;
• and
• wherein the binder material includes at least one material selected from the group consisting of phenol resin, polyisocyanate, polyurethane, epoxy resin, furane resin, polyurethane polymer, phenolic polyurethane, phenol-formaldehyde furfuryl alcohol, urea-formaldehyde furfuryl alcohol, formaldehyde furfuryl alcohol, peroxide, polyphenol resin, resol ester, or mixtures thereof, and
• wherein the binder material is present at a concentration of less than 2 weight percent based on the total weight of the mold.

A method for making a mold for a metal casting comprising the steps of:

• a. coating a plurality of individual uncoated sand particles, having an uncoated diameter, with an acidic activation agent for forming a plurality of individual coated sand particles having a resulting diameter of about 1.0 to about 2.5 times the uncoated diameter;
• b. spreading a layer of the coated sand particles on a workpiece platform by dispensing coated sand particles through an opening of a moveable hopper;
• c. forming a smooth layer having a thickness of from about 0.15 to about 0.30 mm;
• d. selectively contacting the resulting smooth layer with a furane resin binder material, a binder material, or both by dispensing the resin, in droplets of a density of 100 to 600 dots per inch and no earlier than when the furane resin or binder material first contacts the activation agent, through a piezo bending drop-on-demand print head, the binder being dispensed in an amount of about 2 parts binder to 1 part activation agent;
• e. curing the binder at ambient room temperature for causing the binder to crosslink and covalently bond the resin to form a matrix in which the sand particles are dispensed;
• f. repeating at least steps (b)-(e) until a metal casting mold is completed
• wherein the binder material is present at a concentration of less than 2 weight percent based on the total weight of the mold.

A method for manufacturing a three-dimensional metal casting mold, comprising the following successive steps:

• a) providing a plurality of individual particulates comprising sand, wherein at least a portion of a surface of the individual particulates is pre-coated with an activation agent;
• b) contacting a pre-selected portion of the particulates having the activation agent present upon the particulates with a binder material that is activatable by the activation agent;
• and
• c) at least partially hardening the binder material, for forming a layer of the three-dimensional metal casting mold;
• wherein the binder material is present at a concentration of less than 2 weight percent based on the total weight of the mold.