In one example in accordance with the present disclosure, an additive manufacturing system is described. The additive manufacturing system includes a build material distributor to deposit metal powder build material on abed. The additive manufacturing system also includes at least a first electrode below the bed and a second electrode above the bed to generate a non-uniform electric field to compact deposited the metal powder build material. A hardening system of the additive manufacturing system selectively hardens metal powder build material in a pattern of a layer of a three-dimensional object to be printed.

In one example in accordance with the present disclosure, an additive manufacturing system is described. The additive manufacturing system includes a build material distributor to deposit metal powder build material on abed. The additive manufacturing system also includes at least a first electrode below the bed and a second electrode above the bed to generate a non-uniform electric field to compact deposited the metal powder build material. A hardening system of the additive manufacturing system selectively hardens metal powder build material in a pattern of a layer of a three-dimensional object to be printed.

In one example in accordance with the present disclosure, an additive manufacturing system is described. The additive manufacturing system includes a build material distributor to deposit metal powder build material on abed. The additive manufacturing system also includes at least a first electrode below the bed and a second electrode above the bed to generate a non-uniform electric field to compact deposited the metal powder build material. A hardening system of the additive manufacturing system selectively hardens metal powder build material in a pattern of a layer of a three-dimensional object to be printed.

A method for producing a three-dimensional object by selectively solidifying a build material applied layer by layer includes, in at least one process chamber, applying the build material layer by layer to a build platform, generating at least one beam for solidifying the build material using a radiation source, feeding the at least one beam to the build material in the build platform using at least one beam guiding element, and generating a primary gas flow along the build platform using a process assistance device. The process assistance device includes a centre module and at least one outer module aligned with the centre module, so that a section over which primary gas flows is formed between the centre module and the at least one outer module. The centre module and/or the at least one outer module are triggered so as to be movable along the build platform.

A method for producing a three-dimensional object by selectively solidifying a build material applied layer by layer includes, in at least one process chamber, applying the build material layer by layer to a build platform, generating at least one beam for solidifying the build material using a radiation source, feeding the at least one beam to the build material in the build platform using at least one beam guiding element, and generating a primary gas flow along the build platform using a process assistance device. The process assistance device includes a centre module and at least one outer module aligned with the centre module, so that a section over which primary gas flows is formed between the centre module and the at least one outer module. The centre module and/or the at least one outer module are triggered so as to be movable along the build platform.

A system for recoating a powder bed includes a build platform holding a powder bed and an electrode assembly including an electrode and an insulating shield. A voltage supply produces a high voltage alternating current and communicates with the powder bed and the electrode. The electrode assembly is positionable over the powder bed, such that when the electrode assembly is over the powder bed, the shield is between the electrode and the powder bed's top surface. The voltage supply produces a high voltage alternating current that creates an alternating electric field between the electrode and the powder bed that causes the powder of the powder bed top surface to oscillate in a region between the shield and the bed and then reposition themselves on the bed such that the top layer of the powder bed is smoother than it was prior to when the powder particles began oscillating.

A system for recoating a powder bed includes a build platform holding a powder bed and an electrode assembly including an electrode and an insulating shield. A voltage supply produces a high voltage alternating current and communicates with the powder bed and the electrode. The electrode assembly is positionable over the powder bed, such that when the electrode assembly is over the powder bed, the shield is between the electrode and the powder bed's top surface. The voltage supply produces a high voltage alternating current that creates an alternating electric field between the electrode and the powder bed that causes the powder of the powder bed top surface to oscillate in a region between the shield and the bed and then reposition themselves on the bed such that the top layer of the powder bed is smoother than it was prior to when the powder particles began oscillating.

A system for additive manufacturing machine energy beam alignment error compensation includes, a calibration table having x-y planar offsets to correct laser alignment errors representing energy beam positional offsets between beam-steering commanded energy beam locations and fiducial marks generated on a burn-paper, a recoater mechanism that distributes successive layers of powder, one or more sensors monitoring the powderbed surface proximal to the beam scan unit, and a processor unit configured to perform a method. The method including collecting sensor data representing height variations across at least a portion of the powderbed surface, deriving dimensional data from the collected data, analyzing the dimensional data to determine a distribution of differences between the powderbed surface and a calibration plane used for a first spatial calibration, and calculating z-axis calibration offset points for inclusion in the calibration table x-y planar offsets. A method and a non-transitory medium are also disclosed.

An automatic leveling device of a 3D printer, and a 3D printer is provided. The automatic leveling device includes a photoelectric switch, an electromagnetic assembly and a probe assembly. The photoelectric switch is arranged in a housing and defines a photosensitive groove. The electromagnetic assembly is arranged in the housing and defines a sliding hole. The probe assembly is slidably engaged in the sliding hole, and an end of the probe assembly is engaged in the photosensitive groove. The electromagnetic assembly is capable of driving the probe assembly to make the end of the probe assembly move out of the photosensitive groove. The automatic leveling device has the advantages of simple structure, low manufacturing difficulty, low production cost, simple and stable leveling mode, high detection repetition accuracy and no complex circuit and software cooperation.

The present disclosure describes three-dimensional (3D) printing apparatuses, processes, software, and systems for producing high quality 3D objects. Described herein are printing apparatuses that facilitate control of water vapor concentration during one or more printing operations.