A control circuit for generating a primary alternating current (AC) voltage signal provided to a dielectric barrier discharge (DBD) disk of a three-dimensional printer includes a switching regulator receiving a direct current (DC) voltage signal. The switching regulator modulates the DC voltage signal based on a variable duty cycle to create a modulated DC signal. The control circuit also includes a modulation circuit in electrical communication with the switching regulator. The modulation circuit introduces a frequency component to the modulated DC signal, where the primary AC voltage signal includes a variable duty cycle and a set frequency, and the frequency component introduced into the modulated DC signal is representative of the set frequency of the primary AC voltage.

Described herein are methods and compositions for forming three-dimensional objects via material jetting processes, the methods including the repeated steps of selectively depositing a liquid thermoset material onto a surface from a nozzle of at least one jetting head in a first specified direction and exposing at least a portion of the liquid thermoset material to a source of actinic radiation in order to form a three-dimensional object from the cured thermoset material, wherein the jetting head is configured to eject droplets of the liquid thermoset material from the nozzle at prescribed elevated operating temperatures, and wherein the liquid thermoset material is chosen so as to possessing prescribed viscosity and rheological characteristics.

Described herein are methods and compositions for forming three-dimensional objects via material jetting processes, the methods including the repeated steps of selectively depositing a liquid thermoset material onto a surface from a nozzle of at least one jetting head in a first specified direction and exposing at least a portion of the liquid thermoset material to a source of actinic radiation in order to form a three-dimensional object from the cured thermoset material, wherein the jetting head is configured to eject droplets of the liquid thermoset material from the nozzle at prescribed elevated operating temperatures, and wherein the liquid thermoset material is chosen so as to possessing prescribed viscosity and rheological characteristics.

There is disclosed an ink composition for three dimensional (3D) printing. The ink composition comprises: a liquid dispersion of tungsten carbide (WC) particles and cobalt (Co) particles, and, a carrier vehicle for the dispersion of tungsten carbide particles and the dispersion of cobalt particles. The ink composition is of a viscosity usable with ink jet print heads for 3D printing.

There is disclosed an ink composition for three dimensional (3D) printing. The ink composition comprises: a liquid dispersion of tungsten carbide (WC) particles and cobalt (Co) particles, and, a carrier vehicle for the dispersion of tungsten carbide particles and the dispersion of cobalt particles. The ink composition is of a viscosity usable with ink jet print heads for 3D printing.

A three-dimensional printing system can include polymeric build material and jettable fluid(s). The polymeric build material can have an average particle size from 20 μm to 150 μm, a first melt viscosity, and a melting temperature from 75° C. to 350° C. In one example, the jettable fluid can include water, from 0.1 wt % to 10 wt % of electromagnetic radiation absorber, and from 10 wt % to 35 wt % of an organic solvent plasticizer. Contacting a first portion of a layer of the polymeric build material with the jettable fluid can provide an organic solvent plasticizer loading from 2 wt % to 10 wt % based on the polymeric build material content. The first melt viscosity of the polymeric build material at the first portion can be reduced and the melting temperature of the polymeric build material at the first portion can be decreased by 3° C. to 15° C.

A three-dimensional printing system can include polymeric build material and jettable fluid(s). The polymeric build material can have an average particle size from 20 μm to 150 μm, a first melt viscosity, and a melting temperature from 75° C. to 350° C. In one example, the jettable fluid can include water, from 0.1 wt % to 10 wt % of electromagnetic radiation absorber, and from 10 wt % to 35 wt % of an organic solvent plasticizer. Contacting a first portion of a layer of the polymeric build material with the jettable fluid can provide an organic solvent plasticizer loading from 2 wt % to 10 wt % based on the polymeric build material content. The first melt viscosity of the polymeric build material at the first portion can be reduced and the melting temperature of the polymeric build material at the first portion can be decreased by 3° C. to 15° C.

A geometry model is defined of a part targeted for a manufacturing operation that includes an additive process followed by a subtractive process. Potential build orientations of the geometry model used in the additive processes are defined, as are one or more removal tools of the subtractive process. For each of the potential build orientations, supports that are used by the additive process at the orientation are determined. One of the build orientations is selected that minimizes portions of one of the supports that are inaccessible via at least one of the removal tools.

A geometry model is defined of a part targeted for a manufacturing operation that includes an additive process followed by a subtractive process. Potential build orientations of the geometry model used in the additive processes are defined, as are one or more removal tools of the subtractive process. For each of the potential build orientations, supports that are used by the additive process at the orientation are determined. One of the build orientations is selected that minimizes portions of one of the supports that are inaccessible via at least one of the removal tools.

An additive manufacturing system has a light permeable base, a build carrier for holding a workpiece and a light source which is arranged to emit light through the light permeable base. The light permeable base and the build carrier are positionable relative to each other in a build dimension in which the workpiece is built up. The system further has a resin vat in which the light permeable base forms a wall portion thereof. The system further comprises a plurality of resin supplies for supplying different light hardenable resins in direct contact with each other in said vat. The system facilitates the rapid manufacturing of a dental restoration having a color gradation.