Abstract: A system to apply uniform layers of metal powder, the system includes: a conductive roller with a dielectric coating, the conductive roller biased at a first voltage; a powder supply to contain a metal powder biased at a second voltage, the powder supply to provide the metal powder to the conductive roller to form a uniform layer of metal powder on the dielectric coating of the conductive roller; a deposition area to receive the uniform layer of metal powder from the conductive roller, the deposition area biased at a third voltage, wherein the metal powder is transferred across an air gap from the conductive roller to the deposition area by electrostatic attraction of the metal powder.

Abstract: 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.

Abstract: An example method for additive manufacturing of metals includes spreading a build material including a metal in a sequence of layers. Each layer has a respective thickness, a respective sequence position, and a respective exposed surface to receive energy from a flood energy source prior to spreading of a subsequent layer. Each respective exposed surface has a surface area of at least 5 square centimeters (cm2). Layer-by-layer, the exposed surface of each layer is exposed to the radiated energy from the flood energy source. The energy is radiated at an intensity profile and a fluence sufficient to cause a consolidating transformation of the build material in the exposed layer.

Abstract: Introduced here is a self-contained face mask system with an automated liquid-droplet dispensing mechanism (ADM) for humidification. The enclosure of the self-contained mask system can be comprised of one or more layers of breathable fabric adapted to flexibly conform to the face of a user when worn to form a cavity that is adjacent the nostrils and mouth. The ADM of the face mask system can be comprised of a reservoir in which liquid is stored, a respiratory cycle detector, a timer and controller, and a droplet dispenser that controllably dispenses droplets of the liquid from the reservoir into the cavity for inhalation by the user. The ADM can be contained entirely within the face mask enclosure or supported on the surface of the face mask enclosure such that the self-contained mask system, when worn by a user, can be supported entirely by the head and neck of the user.

Abstract: Introduced here is a face mask system having a mask enclosure that contains, or otherwise directly supports, an automated liquid-droplet dispensing mechanism (ADM) for humidification. In operation, the enclosure and ADM are compact and lightweight so that when worn by a user can be supported entirely by the user's head and neck. The enclosure can be comprised of one or more layers of breathable fabric adapted to flexibly conform to the face of a user when worn and form a cavity that is adjacent to the user's nostrils and mouth. The ADM can be comprised of a reservoir in which liquid is stored, a respiratory cycle detector, a timer and controller, and a droplet dispenser that controllably dispenses droplets of the liquid from the reservoir into the cavity for inhalation by the user.

Abstract: An in-situ monitoring device for selective laser melting (SLM) additive manufacturing may include at least one coherent electromagnetic wave source to produce a detection beam, an interferometer interposed between the electromagnetic wave source and a target detection area, a photodetector to detect displacement measuring interference between electromagnetic waves from the electromagnetic wave source and reflected electromagnetic waves from the target detection area through the interferometer, and control logic to cause the detection beam to follow a print path of a material forming laser at a distance behind the material forming laser. The detection beam is placed on a laser-melted and at least partially solidified portion of a layer of a three-dimensional (3D) object formed by the material forming laser.

Abstract: A system for compacting layers of metal powder, including: a layer of metal powder at a first voltage; and a conductive object above the layer of metal powder, the conductive object at a second voltage, wherein a voltage differential between the layer of metal powder and the conductive object is sufficient to attract particles from the layer of metal powder to the conductive object, change the voltage on the particles, and redeposit the particles in the layer of metal powder.

Abstract: An electrophotographic printer includes a charge roller in charge-transferring relation to a photoconductive imaging portion. The printer may determine an AC voltage setpoint of the charge roller.

Abstract: An example method for additive manufacturing of metals includes spreading a build material including a metal in a sequence of layers. Each layer has a respective thickness, a respective sequence position, and a respective exposed surface to receive radiated energy from a flood energy source prior to spreading of a subsequent layer. A energy function is determined based on the metal, the thickness, and the sequence position of an exposed layer. The energy function defines the radiated energy and includes an intensity profile and a fluence sufficient to cause a consolidating transformation of the build material in the exposed layer. The exposed surface of the exposed layer is exposed to the radiated energy from the flood energy source, causing the consolidating transformation of the build material in the exposed layer.

Abstract: An example method for additive manufacturing of metals includes spreading a build material including a metal in a sequence of layers. Each layer has a respective thickness, a respective sequence position, and a respective exposed surface to receive energy from a flood energy source prior to spreading of a subsequent layer. Each respective exposed surface has a surface area of at least 5 square centimeters (cm2). Layer-by-layer, the exposed surface of each layer is exposed to the radiated energy from the flood energy source. The energy is radiated at an intensity profile and a fluence sufficient to cause a consolidating transformation of the build material in the exposed layer.

Abstract: A three-dimensional (3D) printing device may include a pulsed electromagnetic radiation source; a build platform to maintain a number of layers of build material thereon and receive pulsed electromagnetic radiation from the pulsed electromagnetic radiation source; a micromirror array to selectively direct the pulsed electromagnetic radiation from the pulsed electromagnetic radiation source to the build material on the build platform; and a coolant tank with coolant therein to cool the micromirror array.

Abstract: A system for compacting layers of metal powder, including: a layer of metal powder at a first voltage; and a conductive object above the layer of metal powder, the conductive object at a second voltage, wherein a voltage differential between the layer of metal powder and the conductive object is sufficient to attract particles from the layer of metal powder to the conductive object, change the voltage on the particles, and redeposit the particles in the layer of metal powder.

Abstract: An in-situ monitoring device for selective laser melting (SLM) additive manufacturing may include at least one coherent electromagnetic wave source to produce a detection beam, an interferometer interposed between the electromagnetic wave source and a target detection area, a photodetector to detect displacement measuring interference between electromagnetic waves from the electromagnetic wave source and reflected electromagnetic waves from the target detection area through the interferometer, and control logic to cause the detection beam to follow a print path of a material forming laser at a distance behind the material forming laser. The detection beam is placed on a laser-melted and at least partially solidified portion of a layer of a three-dimensional (3D) object formed by the material forming laser.

Abstract: According to examples, an apparatus may include an array of micro-mirrors, each of the micro-mirrors being individually controllable to selectively be in a first position or a second position, and a light source to direct a pulse of light onto the array of micro-mirrors with sufficient intensity to cause micron-sized particles on a powder bed upon which the light is directed from the array of micro-mirrors to at least partially melt. Each of the micro-mirrors that is in the first position may reflect light onto a respective area on a layer of micron-sized particles to at least partially melt the micron-sized particles in the respective area and each of the micro-mirrors that is in the second position may reflect light away from the powder bed on which the micron-sized particles are supported.

Abstract: A device includes a charge roller and a control portion. The charge roller is removably insertable to be in charge-transferring relation to, and spaced apart by a first air gap from, a photoconductive imaging portion of an electrophotographic printer. The control portion is to determine a size of the first air gap based on determination of a charging threshold voltage associated with the charge roller.

Abstract: An electrophotographic printer includes a charge roller in charge-transferring relation to a photoconductive imaging portion. The printer may determine an AC voltage setpoint of the charge roller.

Abstract: Printers with orientable micro-mirrors are disclosed. An example printer includes a first micro-minor, a second micro-minor, a third micro-mirror, an energy source; and a controller. The controller is to, during a first time period, orient the first micro-mirror toward a first area of a powder bed, orient the second micro-minor toward the first area of the powder bed, orient the third micro-mirror toward a second area of the powder bed, and activate the energy source, wherein powder in the first area of the powder bed fuses to form a portion of an object in response to energy directed by the first micro-mirror toward the first area and in response to concurrent direction of energy by the second micro-minor toward the first area.

Abstract: Mounts for micro-mirrors are disclosed. A disclosed example apparatus includes a micro-mirror having a reflective surface area, and a movable mount to support and move the micro-mirror to direct light onto a printing area, where the movable mount includes a cross-sectional profile area that is at least 30% of the reflective surface area of the micro-mirror.

Abstract: A device includes a charge roller and a control portion. The charge roller is removably insertable to be in charge-transferring relation to, and spaced apart by a first air gap from, a photoconductive imaging portion of an electrophotographic printer. The control portion is to determine a size of the first air gap based on determination of a charging threshold voltage associated with the charge roller.

Abstract: A printing device that includes a build platform to hold an amount of build material thereon and a coherent light source to selectively fuse the build material through heat produced by the coherent light source at the surface of the build material wherein the coherent light source flood radiates the entirety of the build platform.