Abstract: In some examples, a printer includes a feed mechanism to distribute a build material on a platform and a heater. The heater includes a lamp, a reflector, and a radiant energy absorbing baffle located between the lamp and the reflector. The lamp and the reflector are to direct radiant energy toward the platform, and the radiant energy is to heat the build material.

Abstract: In an example implementation, a method of fusing layers of 3D parts includes forming a layer of build material, and selectively applying a liquid agent onto the layer of build material to define a part layer of a 3D part and a sacrificial layer of a sacrificial part. The method includes, in a single pass of a thermal energy source over the layer of build material, applying fusing energy to the sacrificial layer, sensing a temperature of the sacrificial layer, adjusting a power level of the thermal energy source based on the sensed temperature, and applying fusing energy to the part layer with the adjusted power level of the thermal energy source.

Abstract: According to an example, an apparatus may include a recoater, an energy source, a carriage supporting the energy source, and a controller. The controller may control the recoater to spread build material particles into a layer on top of a previously applied layer containing fused build material particles and the carriage to move ahead of the recoater to cause the energy source to apply energy onto build material particles in the previously applied layer prior to the recoater spreading the build material particles onto the previously applied layer. The energy source is to heat the fused build material particles to or maintain the fused build material particles at a temperature above a certain temperature and the recoater is to be controlled to spread the build material particles on top of the previously applied layer prior to the fused build material particles falling below the certain temperature.

Abstract: In some examples, an additive manufacturing system includes a dispensing device, an applicator, a thermal energy source, a thermal imaging device, and a controller. The controller is to cause the dispensing device to deposit a layer of build material and cause the applicator to apply the fusing agent to form an object portion and to apply the detailing agent to form a reference portion in the layer of build material. The controller is to cause the thermal energy source to heat the reference portion and to heat and fuse the object portion and cause the thermal imaging device to measure a temperature of the reference portion. The controller is to regulate a power level of the thermal energy source based on a comparison between the temperature of the reference portion and a set-point for the reference portion, which is based on a target temperature for the object portion.

Abstract: Some examples include a method of operating an additive manufacturing machine including forming a layer of a build material, selectively applying a fusing agent onto the formed layer of build material, applying fusing energy to the build material and fusing agent with a thermal energy source to form an object layer of a three dimensional object and a sacrificial layer of a sacrificial object at the selectively applied fusing agent, sensing a thermal temperature of the sacrificial layer, comparing the sensed thermal temperature of the sacrificial layer to a target temperature, and adjusting a power level of the thermal energy source based on the compared temperatures.

Abstract: A control system for a three-dimensional printer includes an energy component interface, an agent depositing component interface, and control logic. The control logic controls the operation of an energy component through the energy component interface and an agent depositing component through the agent depositing component, in forming an output object that is specified in a print job. Additionally, in some examples, the control logic can implement a plurality of modes. Each mode, when selected modulate one or more operational parameters of a least one of the energy component or agent depositing component.

Abstract: In one example, a fusing system for an additive manufacturing machine includes a first carriage carrying a layering device and a fusing lamp, and a second carriage carrying a fusing agent dispenser. The first carriage and the second carriage are movable back and forth over the work area along the same line of motion so that the first carriage follows the second carriage in one direction and the second carriage follows the first carriage in the other direction.

Abstract: In an example implementation, a method of printing a three-dimensional (3D) object includes scanning a print bar in a first direction over a build platform of a 3D printer to deposit a liquid agent onto a layer of build powder. The print bar is then indexed in a second direction substantially orthogonal to the first direction before scanning the print bar back over the build platform in a third direction opposite the first direction to deposit additional liquid agent onto the layer of build powder.

Abstract: A plate disposed between a lamp and a material to be heated is disclosed. The material absorbs a portion of the energy from the lamp and reflects a second portion of the energy. The plate absorbs the reflected energy and transmits the reflected energy back to the material.

Abstract: A build material dispensing device may include a material spreader to spread an amount of build material along a build platform, and at least one hopper for dispensing the build material. The at least one hopper dispenses a plurality of doses of the build material in front of the progression of the material spreader as the material spreader is moved over the build platform.

Abstract: In some examples, an additive manufacturing process may be operated by a method that includes depositing a plurality of preliminary layers of build material over a build surface and applying thermal energy governed by closed-loop control to heat the preliminary layers. The method includes analyzing a temperature distribution across a layer of the preliminary layers to map the locations of any hot spots relative to the build surface. The method includes selecting a spray pattern to apply a cooling agent to the mapped locations.

Abstract: A system determines an object part density relative to a build region in a layer of build material used in an additive manufacturing machine, the object part density based on a relative portion of the build region where an energy absorbing agent is applied. The system controls a thermal characteristic of the build region in the layer of build material based on the determined object part density.

Abstract: An example of a build material for three-dimensional (3D) printing includes a preconditioned polymer or polymer composite powder. A percent crystallinity of the preconditioned polymer or polymer composite powder is reduced by a volume percentage ranging from about 0.5% to about 3% compared to a percent crystallinity of a corresponding untreated polymer or polymer composite powder.

Abstract: According to examples, an apparatus may include fabrication components and a controller. The fabrication components may fabricate an object having a first color. In some examples, the controller may receive an output of a sensor corresponding to a measured value of the first color on the fabricated object. The controller may determine an adjustment value for a parameter of the fabrication components based on the received output. The adjustment value may be correlated to a level of the received output of the sensor. In some examples, the controller may modify a property of the fabrication components based on the determined adjustment value to cause the fabrication components to fabricate subsequent objects based on the adjustment value.

Abstract: An apparatus calibrates the optical sensor to calibrate the distance measured by the sensor with the expected distance using a calibration surface at the expected distance.

Abstract: According to examples, a system may include a first carriage carrying a laying device that may form a build material layer over a build area and a first energy source that may apply energy onto the build material layer as the first carriage is moved over the build material layer. The system may also include a second carriage carrying an agent delivery device and a second energy source, in which the agent delivery device may selectively deliver an agent onto the layer of build material and the second energy source may apply energy onto the agent and the layer of build material as the second carriage is moved across the build material layer. The system may further include a controller to control movement of the first carriage and the second carriage across the build area, in which the first carriage may be independently movable with respect to the second carriage.

Abstract: A three-dimensional (3D) printer build material spreader cooling system may include a build volume, a build material spreader, a spreader drive, a spreader cooler and a cooling fluid supply. The build material spreader may have a length and a first fluid conduit extending along the length. The spreader drive is to translate the build material spreader across the build volume. The spreader cooler is in thermal conductive contact with the build material spreader. The spreader cooler has a second fluid conduit extending along the length. The cooling fluid supply directs cooling fluid in a first direction through the first fluid conduit and in a second direction, opposite the first direction, through the second fluid conduit.

Abstract: In some examples, an additive manufacturing machine includes an unfocused energy source to heat portions of a layer of build material as the unfocused energy source moves across the layer of build material during a build operation of a three-dimensional (3D) object. A focused energy source is controllable to selectively direct focused energy on the layer of build material during the build operation.

Abstract: An additive manufacturing fusing module for use with an additive manufacturing base unit may include a housing, a reflector within the housing, a fusing unit within the housing, an electrical power connector connected to the heating device and having a terminal for releasable connection to a power source and a retainer coupled to the housing to releasably secure the housing to the additive manufacturing base unit.

Abstract: A printing apparatus includes a media bin and a sensor, directed toward the media bin, having a first emitter and a receiver. The printing apparatus further includes a second emitter to emit photons toward the optical sensor, and a controller. The controller determines presence of a print media on the media bin based on a count of photons received from a source other than the first emitter, including the second emitter.