A method for determining a set point for measurements from a temperature sensor of an apparatus for the layer-by-layer formation of a three-dimensional object from particulate material, and associated controllers. The method includes distributing a calibration layer of particulate material over a build bed surface; selectively applying absorption-modifying fluid to a reference area or a surrounding area thereof, on the build bed surface; (c) lowering the build bed surface to a calibration depth, (d) applying heat to the reference area using a moveable heat source while measuring the temperature increase of a sub-reference area over a duration of time and/or taking optical readings of an optical property of the sub-reference area over the duration of time; (e) determining the onset of fusion of the particulate material; and (f) applying the onset of fusion as the set point for subsequent temperature measurements.

A three-dimensional, additive manufacturing system is disclosed. The first and second printer modules form sequences of first patterned single-layer objects and second patterned single-layer objects on the first and second carrier substrates, respectively. The patterned single-layer objects are assembled into a three-dimensional object on the assembly plate of the assembly station. A controller controls the sequences and patterns of the patterned single-layer objects formed at the printer modules, and a sequence of assembly of the first patterned single-layer objects and the second patterned single-layer objects into the three-dimensional object on the assembly plate. The first transfer module transfers the first patterned single-layer objects from the first carrier substrate to the assembly apparatus in a first transfer zone and the second transfer module transfers the second patterned single-layer objects from the second carrier substrate to the assembly apparatus in a second transfer zone. The first and second printer modules are configured to deposit first and second materials under first and second deposition conditions, respectively. The first and second materials are different and/or the first and second deposition conditions are different.

A method of heating a surface while fabricating a 3-D object is disclosed wherein a first temperature feedback signal from a first location on the surface is used to control the energy radiated by an energy source during a first stage of the fabrication process. A second temperature feedback signal from a second location on the surface is used to control the energy radiated by an energy source during a second stage of the fabrication process.

A method of heating a surface while fabricating a 3-D object is disclosed wherein a first temperature feedback signal from a first location on the surface is used to control the energy radiated by an energy source during a first stage of the fabrication process. A second temperature feedback signal from a second location on the surface is used to control the energy radiated by an energy source during a second stage of the fabrication process.

In one example, a lighting device for an additive manufacturing machine includes first light sources each to emit monochromatic light within a first band of wavelengths that includes a peak light absorption of a liquid coalescing agent and second light sources each to emit monochromatic light within a second band of wavelengths different from the first band of wavelengths. Each of the first light sources or each of multiple groups of the first light sources is individually addressable to emit monochromatic light independent of any other of the first light sources or of any other group of the first light sources and each of the second light sources or each of multiple groups of the second light sources is individually addressable to emit monochromatic light independent of any other of the second light sources or of any other group of the second light sources.

In one example, a lighting device for an additive manufacturing machine includes first light sources each to emit monochromatic light within a first band of wavelengths that includes a peak light absorption of a liquid coalescing agent and second light sources each to emit monochromatic light within a second band of wavelengths different from the first band of wavelengths. Each of the first light sources or each of multiple groups of the first light sources is individually addressable to emit monochromatic light independent of any other of the first light sources or of any other group of the first light sources and each of the second light sources or each of multiple groups of the second light sources is individually addressable to emit monochromatic light independent of any other of the second light sources or of any other group of the second light sources.

In one example, a non-transitory processor readable medium with instructions thereon that when executed cause an additive manufacturing machine to inhibit build material in an overlying layer of build material from fusing with a first slice formed in an underlying layer of build material.

In one example, a non-transitory processor readable medium with instructions thereon that when executed cause an additive manufacturing machine to inhibit build material in an overlying layer of build material from fusing with a first slice formed in an underlying layer of build material.

3-D printing transfers build material and support from an intermediate transfer belt (ITB) to a platen. The build material is the same as the support material, except that the build material includes a photoinitiator and the support material does not. The platen moves to make contact with the ITB, and the ITB transfers successive layers of build material and support material each time the platen contacts the ITB. The platen and a portion of the ITB that is adjacent the platen are heated prior to the platen contacting the ITB, and the same is exposed so as to crosslink polymers of build material, without crosslinking polymers of support material. The polymers of build material being crosslinked and the polymers of support material not being crosslinked makes the support material selectively soluble in a solvent.

Layers of build and support material on an intermediate transfer surface are moved past a transfuse station and a platen moves relative to the intermediate transfer surface to contact the platen to one of the layers on the intermediate transfer surface. The intermediate transfer surface transfers a layer of the build material and the support material to the platen each time the platen contacts the layers on the intermediate transfer surface at the transfuse station to successively form a freestanding stack of the layers of build and support material on the platen. The build material has a higher melting temperature than the support material. A support material removal station heats the stack to a temperature above the melting temperature of the support material, but below the melting temperature of the build material, to melt the support material, but leave a 3-D structure made of only the build material.