Abstract: In an example, a method includes in an additive manufacturing process, generating a first object and generating an ancillary object on top of the first object to reduce a thermal gradient of the first object during cooling.

Abstract: Examples of a method of operating an additive manufacturing system, a three-dimensional (3D) printing system and a non-transitory machine-readable medium are described. In an example, a build material is supplied to a print region of an additive manufacturing system. A temperature distribution, corresponding to a pattern, of at least a surface of the build material is generated. An image of the pattern is captured using a thermal sensor. Image data representative of the image of the pattern is compared with data representative of an expected position of the pattern. On the basis of the comparing, difference data indicative of a difference between a position of the thermal sensor during capture of the image and an expected position of the thermal sensor associated with the expected position of the pattern is generated. Operation of the additive manufacturing system is controlled at least in dependence on the difference data.

Abstract: A method of controlling temperature in an apparatus for generating a three-dimensional object comprises performing a calibration test on a sample of build material that is to be used in generating a three-dimensional object, calibrating at least one temperature point from the calibration test, and using the at least one calibrated temperature point during subsequent temperature control of the apparatus.

Abstract: In an example, a method includes forming, at an additive manufacturing apparatus, a first layer of build material to be processed in the generation of an object. A print agent is selectively applied onto the first layer based on a first print instruction associated with the first layer. Energy is applied to the first layer to cause fusion in a region of the first layer. The method further comprises: measuring the temperature of the first layer at a plurality of locations to form a measured temperature distribution profile; comparing the measured temperature distribution profile against a predicted temperature distribution profile to generate a difference; and correcting a temperature distribution profile of a subsequent layer of the build material following fusion of the subsequent layer based on the difference by modifying a second print instruction associated with the subsequent layer.

Abstract: In an example, a method includes measuring the temperature of a fused region and the temperature of an unfused region of a first layer of build material; determining a preheating setting for a subsequent layer of build material in response to the measured temperature of the unfused region of the first layer; determining a print instruction for applying print agent to the subsequent layer of build material, wherein the application of print agent prescribed by the print instruction for the subsequent layer to cause the temperature of the preheated build material to be a predetermined temperature prior to fusion in response to the measured temperature of the fused region of the first layer; forming the subsequent layer of build material; preheating the subsequent layer of build material in accordance with the preheating setting; and selectively applying the print agent onto the subsequent layer based on the print instruction.

Abstract: In an example, a method includes receiving, at a processor, data representing a three dimensional object. Using the processor, a modified data representation of the three dimensional object may be determined wherein, in the modified data representation, the three dimensional object is represented in terms of homogenous sub-volumes. Each homogenous sub-volume is homogenous with respect to a predetermined attribute and contains locations which are within a common object boundary distance band of plurality of object boundary distance bands, wherein at least two object boundary distance bands partially overlap.

Abstract: Apparatus, computer readable medium, or method to determine a layer volume change in a processed layer of powder, and distribute an additional amount of powder in a subsequent layer based on the determined layer volume change.

Abstract: Examples are described that generate control data for production of a three-dimensional object. Build material profile data is accessed for an indicated build material. The build material profile data for a given build material defines one or more parameter values that are dependent on the properties of the given build material and that are configured to generate a three-dimensional object with predefined build properties.

Abstract: In one example, a non-transitory processor readable medium with instructions thereon that when executed cause an additive manufacturing machine to: form a first layer of build material; form a second layer of build material over the first layer; solidify build material in the second layer to form a slice; and form a barrier that is separable from the slice to prevent a coalescing agent in the second layer penetrating build material in the first layer.

Abstract: Examples are described that generate control data (280) for production of a three-dimensional object. Build material profile data (260) is accessed for an indicated build material. The build material profile data for a given build material defines one or more parameter values that are dependent on the properties of the given build material and that are configured to generate a three-dimensional object with predefined build properties. Certain examples are arranged to generate control data for the production of a three-dimensional object by applying build material profile data to received object data (230).

Abstract: In an example, a method includes measuring a temperature of a plurality of regions of a layer of build material in an additive manufacturing apparatus to provide initial temperature values. For each of a plurality of regions which comprise build material which is intended to fuse, an average temperature value of a plurality of neighbouring regions may be determined and the initial temperature values may be replaced with the average temperature value. Based on the replacement temperature values, a representative temperature of an area of the layer of build material may be determined and a heat source may be controlled based on the representative temperature.

Abstract: Certain examples described herein relate to preparing a base of build material for additive manufacturing. The base is formed from layers of build material that do not form part of an object undergoing additive manufacture. The base is heated by the application of energy, for example using a radiation source. A thermal profile of the base is measured after heating and is used to determine a pattern of application of at least one printing agent to the base. The pattern of application is used to deposit the at least one printing agent upon the base, wherein the presence of the printing agent affects the heating of the base. In this way the pattern of application of printing agent may be used to effect a thermal homogeneity of the base.

Abstract: As one example, a printer includes a density calculator to determine a content density of data on page to be printed and a controller. In that example, the controller may perform operations to determine a dry time for a swath of the page to be printed based on the content density and an environmental variable and adjust a parameter for the page to be printed to mitigate a drying time of the page to be printed based on the dry time determined for the swath.

Abstract: A controller-implemented method of controlling a three dimensional (3D) printing process, comprises presenting printing options (20) of the 3D printing process at a user interface (16); accepting settings (22) from the user interface (16) based on the presented printing options (20); determining a printing instruction (24) based on the settings (22), the printing instruction (24) to be used to manufacture a three-dimensional (3D) object; and determining a post-processing instruction (26) based on the settings (22), the post-processing instruction (26) to be used in post-processing the 3D object.

Abstract: According to one example, there is provided a printing system. The printing system comprises a support having a plurality of spaced apertures and a colour sensor moveable to measure light from each aperture. The printing system further comprises a controller to control the colour sensor to measure characteristics of light emitted through each aperture, and to determine, for each aperture, light calibration data.

Abstract: According to an example, a three-dimensional (3D) printer may include a delivery device to selectively deliver liquid droplets onto a layer of build materials and a controller to determine a preselected area on the layer of build materials at which the delivery device is to deliver liquid droplets, to determine a distribution at which gaps are to be formed in the delivery of the liquid droplets within the preselected area, and to control the delivery device to deliver the liquid droplets across the preselected area while forming the gaps at the determined distribution, in which the gaps are to form heat sinks in the build materials that are to prevent heat spikes from occurring across the build materials in the preselected area.

Abstract: According to an example, a computing apparatus may include a processing device and a machine readable storage medium on which is stored instructions that when executed by the processing device, cause the processing device to access, from a sensing device, information pertaining to formation of a part of a 3D object in a layer of build materials upon which fusing agent droplets have been or are to be selectively deposited. The instructions may also cause the processing device to predict, based upon the accessed information, a quality of the part and output an indication of the predicted quality of the part.

Abstract: In an example, a method includes measuring the temperature of a fused region and the temperature of an unfused region of a first layer of build material; determining a preheating setting for a subsequent layer of build material in response to the measured temperature of the unfused region of the first layer; determining a print instruction for applying print agent to the subsequent layer of build material, wherein the application of print agent prescribed by the print instruction for the subsequent layer to cause the temperature of the preheated build material to be a predetermined temperature prior to fusion in response to the measured temperature of the fused region of the first layer; forming the subsequent layer of build material; preheating the subsequent layer of build material in accordance with the preheating setting; and selectively applying the print agent onto the subsequent layer based on the print instruction.

Abstract: In one example, a system for heating lamp calibration can include a plurality of heating lamps over a print bed to heat the print bed over a period of time, a thermal imaging sensor to capture images of the print bed over the period of time, and a computing device coupled to the thermal imaging sensor to determine a surface flux delivered to each of a plurality of zones of the print bed over the period of time and calibrate a heating lamp of the plurality of heating lamps based on a corresponding contribution to the surface flux.

Abstract: In an example, a method includes forming, at an additive manufacturing apparatus, a first layer of build material to be processed in the generation of an object. A print agent is selectively applied onto the first layer based on a first print instruction associated with the first layer. Energy is applied to the first layer to cause fusion in a region of the first layer. The method further comprises: measuring the temperature of the first layer at a plurality of locations to form a measured temperature distribution profile; comparing the measured temperature distribution profile against a predicted temperature distribution profile to generate a difference; and correcting a temperature distribution profile of a subsequent layer of the build material following fusion of the subsequent layer based on the difference by modifying a second print instruction associated with the subsequent layer.