Abstract: According to an example, a printer may include a warming device to apply energy onto a region of a plurality of regions of a layer of build materials. The printer may also include a controller that may calculate, based upon the region upon which the warming device is to apply energy, an energy curve to be applied to the warming device between occurrences of a plurality of events, in which the energy curve defines timings and levels at which the warming device is to be operated between occurrences of the plurality of events. The controller may also control the warming device to be operated to apply energy onto the region according to the calculated energy curve.

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 printhead maintenance apparatus includes a pump, a current monitor and processing circuitry. The pump may be provided to increase a pressure in a printhead, and the current monitor may monitor a current consumption of the pump. The processing circuitry may determine a rate of change of current consumption of the pump, and compare the rate of change of current consumption to a predetermined threshold.

Abstract: In an example, a method includes forming a first layer of build material to be processed in object generation and selectively applying at least one print agent on to the first layer based on a print instruction for the first layer. Energy may be applied to the first layer to cause fusion in at least a region thereof, and at least one temperature associated with a thermal contribution of the first layer to a subsequent layer of build material to be processed in object generation may be measured. It may be determined if a temperature condition indicative of a departure from an anticipated thermal contribution of the first layer to a region of subsequent layer exists. If such a temperature condition does exist, a print instruction for applying print agent to the region of the subsequent layer based on the temperature condition may be determined.

Abstract: A method comprises switching on a first radiation source of a plurality of radiation sources. The plurality of radiation sources are for delivering radiation towards a print area of a printing apparatus. Each of the plurality of radiation sources may be connected to control circuitry via one of a plurality of circuit terminals. The method may further comprise detecting, using a detector, a change resulting from radiation from the first radiation source. The method may further comprise determining, using a processor, based on the detected change, connection information indicative of the circuit terminal to which the first radiation source is connected.

Abstract: According to some examples, a method comprises measuring, using a detector, a temperature of at least a portion of a layer of build material formed on a print bed associated with an additive manufacturing apparatus. The additive manufacturing apparatus may include a heating module to direct heat towards successive layers of build material during a series of successive passes over the build material. The method may further comprise determining, using a processor, based at least in part on the measured temperature, a duration that the heating module is to wait before performing a pass over the build material, and a speed at which the heating module is to travel over the build material.

Abstract: Measures for use in an additive manufacturing system. A thermal camera measures temperatures of a printbed area of the system at a first time and a second, subsequent time during additive manufacture of an object in the printbed area. A controller receives, from the thermal camera, temperature information associated with the measured temperatures at the first time and the second time and processes the received temperature information to determine a first position of a moving part of the system at the first time and a second position of the moving part at the second time. In response to the processing indicating that the moving part has not moved by a sufficient amount between the first time and the second time, the controller determines that the moving part is operating abnormally.

Abstract: In an example, a print apparatus includes a printhead carriage to receive a printhead comprising a print agent ejection nozzle, a drop detector to acquire a signal indicative of variations in a parameter detected by the drop detector over a period of drop detection, a memory to hold a print agent ejection signature, and processing circuitry. The processing circuitry includes a convolution module to convolve the drop detector signal with the print agent ejection signature, and the processing circuitry is to determine, from an output of the convolution module, an indication of similarity between the drop detector signal and the print agent ejection signature.

Abstract: Measures for use in an additive manufacturing system. The temperature of at least one build material delivery hole in a printbed area of the system is measured. An emissivity of the at least one build material delivery hole is compared with a known emissivity of a build material being used in additive manufacturing by the system at the measured temperature. In response to the comparison indicating a difference in emissivity, it is determined that at least a portion of the at least one build material delivery hole is not covered by build material.

Abstract: In an example implementation, a first fusing lamp of a fusion assembly in a 3-dimensional printer is illuminated during a number of processing cycles for generating a 3D object, and a second fusing lamp of the fusion assembly is illuminated during a subsequent number of processing cycles for generating the 3D object.

Abstract: Examples include apparatuses, processes, and methods for generating three-dimensional objects. An example apparatus comprises build material distributor and a controller. Examples distribute a particular build layer in a build area of the apparatus over a previous build layer. Examples determine a build layer temperature corresponding to the particular build layer. Examples analyze build layer coverage for the particular build layer based at least in part on a build layer temperature of the previous build layer and the build layer temperature of the particular build layer. Examples selectively recoat the particular build layer with additional build material based at least in part on the build layer coverage for the particular build layer.

Abstract: There is provided a method and apparatus for controlling heat to a build surface. A thermal profile over the build surface is determined. The determined thermal profile over the build surface is compared with an expected thermal profile over the build surface. Based on the comparison, the determined thermal profile over the build surface or the expected thermal profile over the build surface is selected to control an amount of heat provided by a heating module to the build surface.

Abstract: Examples of determining the temperature of a print zone in an additive manufacturing system are described. In one case, the additive manufacturing system comprises a print zone, a radiation source, an infra-red sensor and an ambient light sensor. The infra-red sensor is configured to measure the temperature of the print zone, and the ambient light sensor is configured to measure visible electromagnetic radiation. The additive manufacturing system comprises a temperature controller to compensate data from the infra-red sensor for infra-red radiation from the radiation source using data from the ambient light sensor.

Abstract: Method and apparatus for sending and receiving data in a wireless machine to machine communication network comprising at least a gateway (2) and a plurality of nodes (4), implementing an hybrid Medium Access Control protocol to access the shared medium. In order to prevent collisions when sending data transmissions (26), nodes (4) request access to the medium with access request packets (25), and are informed by the gateway (2) if said access request packets (25) are received correctly or if a collision occurred. According to the feedback information (24) provided by the gateway (2), nodes (4) are organized in a distributed queuing system with separate queues collision resolutions and data transmissions (26). Time slots (19) with fixed length are used, divided into three separate subperiods for feedback information (24), access request packets (25) and data transmissions (26). The method and apparatus further implements channel hopping to reduce interferences from adjacent networks.

Abstract: Temperatures of a layer of build material on a support member may be detected. Each of the temperatures corresponding to a respective area of the layer. Based on data representing the three-dimensional object, a subset of the temperatures may be filtered from spatial temperature distribution data comprising the temperatures. A degree of heat or energy applied to the layer may be controlled based on the filtered spatial temperature distribution data.

Abstract: A sensor may be to detect a height profile of build material for generating the three-dimensional object. A defect of the build material may be determined to exist based on the height profile of the build material. The defect may be corrected or the defect may be prevented from impacting a component of the system. A portion of a layer of the build material delivered by a build material distributor may be selectively solidified.

Abstract: A method of controlling a heating sub-system in an additive manufacturing system. The method comprising receiving thermal imaging information from a temperature sensing subsystem, receiving additive manufacturing media concentration information from an additive manufacturing media concentration information database, on the basis of the received thermal imaging information and additive manufacturing media concentration information, for each pixel area in the plurality of pixel areas, determining the temperature for each additive manufacturing media agent in the plurality of additive manufacturing media agents which is present in the respective pixel area, and on the basis of the determined temperatures for each pixel area and additive manufacturing media agent, controlling the power to a heating subsystem employed in the given additive manufacturing process.

Abstract: A method for thermal control in an additive manufacturing system is disclosed: the method including receiving position information from an encoder device, receiving a data stream from a thermal sensing device, filtering the data stream based on the position information and building a temperature image map from the filtered data stream. A thermal control system and an additive manufacturing system having a thermal control system are also disclosed.

Abstract: In some examples, a method comprises sensing a temperature of a plurality of sub-regions of a portion of a layer of build material in an object generation apparatus. A frequency distribution of sub-region temperatures may be derived therefrom and it may be determined whether the frequency distribution is bimodal. If the frequency distribution is not bimodal, a build material temperature zone is identified. If however the frequency distribution is bimodal, a fusing build material temperature zone and a non-fusing build material temperature zone are identified. The method may further comprise determining a nominal temperature of the at least one identified temperature zone.

Abstract: A method for determining a parameter of a process associated with a 3D printing process provided. A first amount corresponding to an object of fused powder surrounded by non-fused powder is used. The first amount is separated into a second amount of non-fused powder and a third amount corresponding to the object including residual powder material attached. The residual powder material is removed from the object using a fourth amount of a cleaning agent. A fifth amount corresponding to the fused powder of the cleaned object and a sixth amount of material corresponding to a mixture of the removed residual powder material and the cleaning agent is obtained. The mixture includes a seventh amount of material being recovered, an eighth amount of material corresponding to powder material wastage, and the fourth amount. The parameter is derived from at least two of first to eighth amounts of material.