In one example, a memory having instructions thereon that when executed cause a 3D printing system to repeatedly form each of multiple successive layers of powdered build material on a platform and apply a functional agent to build material in each layer, create a pressure difference across a thickness of build material on the platform, and increase the pressure difference over an extent of build material on the platform as the build material on the platform gets thicker.

In a three-dimensional printing method example, a metallic build material is applied. A positive masking agent is selectively applied on at least a portion of the metallic build material. The positive masking agent includes a radiation absorption amplifier that is compatible with the metallic build material. The metallic build material is exposed to radiation from a spatially broad, high energy light source to melt the portion of the metallic build material in contact with the positive masking agent to form a layer. The radiation absorption amplifier i) has an absorbance for the radiation that is higher than an absorbance for the radiation of the metallic build material, or ii) modifies a surface topography of the at least the portion of the metallic build material to reduce specular reflection of the radiation off of the at least the portion of the metallic build material, or both i) and ii).

The present disclosure generally relates to additive manufacturing systems and methods involving a mechanism for feeding in a desired amount of fresh recoater blade. This can be accomplished by, for example, spooling the fresh blade material from a spool. This helps prevent work stoppage when a portion of a recoater blade becomes damaged. As such, the present disclosure also relates to a system and method for detecting whether a recoater blade is damaged, and if there is damage, then causing a fresh blade portion to be fed in.

In one example, a roller control process for a 3D printer includes stopping the layering roller rotating at angular home before the roller reaches linear home at the end of a fusing pass, measuring the duration between when the roller reaches angular home and when the roller reaches linear home, and, if the duration exceeds a threshold, then stopping the roller rotating at angular home at a distance closer to linear home in subsequent fusing passes until the duration does not exceed the threshold.

A powder recirculation system for an apparatus for manufacturing a three-dimensional object (500) from powder is provided. The powder recirculation system comprises: a delivery path coupled to an outlet of a powder tank (410), the powder tank configured to store the powder; a powder repository (115) coupled to an outlet of the delivery path, the delivery path comprising a delivery mechanism for delivering the powder from the powder tank to the powder repository; a powder recirculation path coupled to an outlet (102) of the powder repository, wherein the powder recirculation path is configured to return first excess powder from the powder repository to the delivery path at a location (103, 104) upstream of the outlet of the powder tank.

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.

An apparatus configured to model a three-dimensional modeled object, includes a carrier, an energy applying unit, and a flying unit. The carrier is configured to carry a modeling material. The energy applying unit is configured to apply energy to a surface of a modeled object. The flying unit is configured to fly the modeling material carried on the carrier toward the surface of the modeled object, the energy being applied to the surface.

An apparatus configured to model a three-dimensional modeled object, includes a carrier, an energy applying unit, and a flying unit. The carrier is configured to carry a modeling material. The energy applying unit is configured to apply energy to a surface of a modeled object. The flying unit is configured to fly the modeling material carried on the carrier toward the surface of the modeled object, the energy being applied to the surface.

A lamination fabricating method includes forming a powder layer including a powder for three-dimensional fabrication, applying a fabrication liquid to the powder layer, repeating the forming of the powder layer and the forming the powder layer to form a fabricated object, and forming a base layer prior to the forming of the powder layer. A powder filling rate of the base layer is higher than a powder filling rate of the powder layer.