Abstract: According to examples, an apparatus may include an agent delivery device to deliver a coalescing agent to a selected location of a build material layer and a plurality of microwave energy emitters, each of which may include a tip to generate a focused microwave energy field onto a respective area near the tip. The apparatus may also include a controller that may control delivery of a first signal to a first microwave energy emitter of the plurality of microwave energy emitters; receive an energy feedback signal corresponding to energy reflected back into the first microwave energy emitter; determine, based on the received energy feedback signal, a power level of a second signal to be delivered to a microwave energy emitter of the plurality of microwave energy emitters; and control delivery of the second signal at the determined power level to the microwave energy emitter.

Abstract: According to examples, an apparatus may include an agent delivery device to deliver a coalescing agent to selected locations of a build material layer and a plurality of microwave energy emitters, each of the microwave energy emitters including a tip to generate a focused microwave energy field onto a respective area near the tip, in which the tip is to be positioned to place a portion of the build material layer within the focused microwave energy field. The apparatus may also include a controller that may control the microwave energy emitters to direct microwave energy onto the build material layer.

Abstract: In some examples, a controller receives measurement data responsive to operation of a vibrated spreader for use in dispensing a build material onto a target surface, and controls a frequency of a vibration of the spreader based on the measurement data.

Abstract: According to an example, a three-dimensional (3D) printer may include a spreader to spread build material granules into a layer on a build area platform, a pressing die positioned above the layer of spread build material granules, in which the pressing die is to apply pressure onto the layer of build material granules to fragment the build material granules into primary particles to increase the density of the layer of build material granules, and a printhead to selectively deposit a fusing agent between the primary particles of the spread layer of build material granules.

Abstract: In an example implementation, a sintering system includes a detection gas line to enable gas to flow into a sintering furnace from an external gas supply. The system includes a detection gas port inside the furnace through which gas from the detection gas line is to flow into the furnace, and a registration feature inside the furnace to enable positioning of a token green object proximate the gas detection port. The system includes a gas flow monitor to detect changes in gas flow through the detection gas line when the token green object shrinks during a sintering process in the furnace.

Abstract: In an example implementation, a method of determining a sintering process endpoint includes monitoring gas flow through a detection gas line routed into a sintering furnace and through a furnace shelf on which a token green object is positioned. The method includes detecting a change in the gas flow when the token green object shrinks during a sintering process in the furnace, and determining that green objects being sintered in the furnace have reached a sintering endpoint when the change in the gas flow reaches a predetermined target.

Abstract: A system and method for additive manufacturing (AM) including forming a product via AM, placing a resonator adjacent the product as the product is being formed in the AM, and determining a property of the product. The resonator operates over a microwave frequency spectrum and emanates electromagnetic energy.

Abstract: A device for forming spherical particles may include a receiving chamber having a heating portion and a cooling portion. Wire segments may travel in a free fall through the receiving chamber. While falling through the heating portion, wire segments may be heated to form spherical particles in response to exposure to microwave electromagnetic radiation. While falling through the cooling portion, formed spherical particles cool.

Abstract: A three-dimensional (3D) object printing kit includes a polymeric material; a fusing agent including at least 5 vol % of a polar solvent; and a detailing agent. The detailing agent includes a non-polar, hydrophobic substance selected from the group consisting of a non-polar, hydrophobic liquid in its liquid state at a temperature ranging from about ?80° C. to about 40° C., and a non-polar, hydrophobic wax having a melting temperature less than 120° C.

Abstract: An apparatus is disclosed to create a breakaway junction for 3D printed parts. Powder is spread along a target zone, such as a build bed. A liquid functional agent is selectively dispensed upon the powder to form a 3D object, a supporting part, and the breakaway junction between them.

Abstract: In a 3D printing method, a first layer of a build material is applied. A part layer is patterned by selectively applying a penetrating liquid functional material (PLFM) on at least a portion of the first layer. The PLFM includes (in amounts by weight based on total wt % of the PLFM): from about 5%-15% of a first metal oxide nanoparticle having a particle size ranging from about 0.5 nm up to 10 nm, from about 0.25%-10% of a second metal oxide nanoparticle having at least one dimension greater than 10 nm, from about 1%-10% of an electromagnetic radiation absorber, from about 5%-50% of an organic solvent, a surfactant, and a balance of water. The first layer having the PLFM applied thereon is exposed to electromagnetic radiation, whereby the portion of the first layer at least partially fuses to form the part layer.

Abstract: In an example implementation, a method of operating a sintering furnace includes receiving information about a green object load to be sintered in a sintering furnace, determining a sintering profile based on the information, and performing a sintering process according to the sintering profile. During the sintering process, a sensor reading that indicates a degree of densification of a green object in the load is accessed from a densification sensor. The method includes initiating a cool down phase of the sintering process if the sensor reading has reached a target sensor reading.

Abstract: In example implementations, a method for extracting layers of build material into a carrier. The method includes providing a layer of build material onto a bed. Portions of the layer of build material on the bed are digitally printed with a liquid functional material (LFM). The method repeats providing the layer of build material and digitally printing without applying energy to the LFM to define a structure in layers of build material on the bed. The layers of build material are extracted into a carrier and the carrier is removed.

Abstract: According to examples, an apparatus may include a processor and a memory on which are stored machine readable instructions that when executed by the processor, cause the processor to determine whether a first surface map includes a dropout, the first surface map being generated using a first image parameter on a first image and a second image. The instructions may also cause the processor to, based on a determination that the first surface map includes a dropout, recover information corresponding to the dropout. The instructions may further cause the processor to generate a recovered surface map using the recovered information and store the recovered surface map.

Abstract: In example implementations, an apparatus includes a housing, a movable base, a tab portion and a coupling mechanism. The housing is comprised of a microwave transparent material. The movable base is coupled to the housing to receive build material that is digitally printed. The tab portion is coupled to a bottom portion of at least one wall of the housing. The tab portion stops the movable base. The coupling mechanism is coupled to the housing to removably attach the apparatus to a three dimensional printer.

Abstract: In one example, a processor readable medium having instructions thereon that when executed cause an additive manufacturing machine to vary operating characteristics of a fusing laser beam at multiple different voxel locations in a layer of build material according to an energy dosage to be applied at each voxel location in an object slice, including multiple different energy dosages for corresponding multiple different voxel locations in the slice.

Abstract: In example implementations, a method for extracting layers of build material into a carrier. The method includes providing a layer of build material onto a bed. Portions of the layer of build material on the bed are digitally printed with a liquid functional material (LFM). The method repeats providing the layer of build material and digitally printing without applying energy to the LFM to define a structure in layers of build material on the bed. The layers of build material are extracted into a carrier and the carrier is removed.

Abstract: In an example of a method for three-dimensional (3D) printing, build material layers are patterned to form an intermediate structure. During patterning, a binding agent is selectively applied to define a patterned intermediate part. Also during patterning, i) the binding agent and a separate agent including a gas precursor are, or ii) a combined agent including a binder and the gas precursor is, selectively applied to define a build material support structure adjacent to at least a portion of the patterned intermediate part. The intermediate structure is heated to a temperature that activates the gas precursor to create gas pockets in the build material support structure.

Abstract: In example implementations, an apparatus includes a housing, a movable base, a tab portion and a coupling mechanism. The housing is comprised of a microwave transparent material. The movable base is coupled to the housing to receive build material that is digitally printed. The tab portion is coupled to a bottom portion of at least one wall of the housing. The tab portion stops the movable base. The coupling mechanism is coupled to the housing to removably attach the apparatus to a three dimensional printer.

Abstract: A stabilizing liquid functional material (SLFM) for 3D printing includes ceramic nanoparticles in an amount ranging from about 0.25% to about 5% by weight based on a total SLFM weight and silica nanoparticles present in an amount ranging from about 0.1% to about 10% by weight based on the total SLFM weight. The ceramic nanoparticles have a particle size ranging from about 5 nm to about 50 nm. The silica nanoparticles have a particle size ranging from about 10 nm to about 50 nm. The ceramic nanoparticles and the silica nanoparticles are different in composition and/or morphology. An electromagnetic radiation absorber is present in an amount ranging from about 1% to about 10% by weight based on the total SLFM weight. An organic solvent is present in an amount from about 5% to about 50% by weight based on the total SLFM weight. The SLFM includes a balance of water.