Abstract: Methods of layerwise fabrication of a three-dimensional object, and objected obtained thereby are provided. The methods are effected by dispensing at least a first modeling formulation and a second modeling formulation to form a core region using both said first and said second modeling formulations, an inner envelope region at least partially surrounding said core region using said first modeling formulation but not said second modeling formulation, and an outer envelope region at least partially surrounding said inner envelope region using said second modeling formulations but not said first modeling formulation; and exposing said layer to curing energy, thereby fabricating the object, The first and second modeling formulations are selected such they differ from one another, when hardened, by at least one of Heat Deflection Temperature (HDT), Izod Impact resistance, Tg and elastic modulus.

Abstract: An inkjet printing method and inkjet compositions are disclosed. The method includes selectively depositing by inkjet printing, layer by layer, a first composition and a second composition onto a receiving media from different dispensers to form polymerizable deposited layers. The first composition includes one or more free-radical polymerizable compounds and a cationic photoinitiator and is devoid of compounds able to undergo cationic photopolymerization within the first composition. The second composition includes one or more cationic polymerizable compounds and is devoid of cationic photoinitiators. At least one of the compositions includes a radical photoinitiator. The method further includes exposing the deposited layers to actinic radiation to initiate polymerization of the free-radical polymerizable compounds and the cationic polymerizable compounds within the deposited layers.

Abstract: Methods of printing a 3D object comprising depositing a building material, layer by layer, via printing heads comprising one or more nozzle arrays; and activating each of said printing heads to dispense a building material at least once within a specified period of time during printing to form a portion of said bulk region according to data provided by a CAD file, and activating said printing heads to deposit the building material to form another portion of the bulk region without relating to said data.

Abstract: Modeling material formulations and formulation systems usable in additive manufacturing of a three-dimensional object, featuring, when hardened, a Shore A hardness lower than 10 and/or a Shore 00 hardness lower than 40, are provided. Additive manufacturing processes utilizing these formulations and formulation systems, and three-dimensional objects obtainable thereby, are also provided.

Abstract: A system for three-dimensional printing is disclosed. The system comprises: a rotary tray configured to rotate about a vertical axis; a printing head, each having a plurality of separated nozzles; and a controller configured for controlling the inkjet printing head to dispense, during the rotation, droplets of building material in layers, such as to print a three-dimensional object on the tray.

Abstract: Novel support material formulations, characterized as providing a cured support material with improved dissolution rate, while maintaining sufficient mechanical strength, are disclosed. The formulations comprise a water-miscible non-curable polymer, a first water-miscible, curable material and a second, water-miscible material that is selected capable of interfering with intermolecular interactions between polymeric chains formed upon exposing the first water-miscible material to curing energy. Methods of fabricating a three-dimensional object, and a three-dimensional object fabricated thereby are also disclosed.

Abstract: A method of fabricating a cross-layer pattern in a layered object is disclosed. The method is executed by an additive manufacturing system and comprises: dispensing a patterning material onto a receiving medium to form a first pattern element; dispensing a first layer of modeling material onto the first pattern element while forming a first open cavity exposing at least a portion of the first pattern element beneath the first layer; and dispensing patterning material onto the exposed portion of the first pattern element and the first layer to form a second pattern element contacting the first pattern element.

Abstract: An additive manufacturing (AM) system includes a carriage that deposits material in a defined pattern and a building platform that receives material deposited from the carriage. The carriage includes a pre-heating assembly with a plurality of pre-heating chambers and a printing block with a plurality of slots for receiving a plurality of printing heads. The carriage is equipped with more pre-heating chambers than head slots.

Abstract: A method of additive manufacturing of a three-dimensional object includes sequentially dispensing and solidifying a plurality of layers. The plurality of layers may be formed with a plurality of different colored model materials, a flexible material arranged in a configured pattern to form a sacrificial structure at least partially encompassing the object, and a soft material. The soft material is arranged in a configured pattern to provide separation between the model material and the sacrificial structure. The plurality of different colored model materials is arranged in a configured pattern corresponding to the shape and color definition of the object.

Abstract: A system for three-dimensional printing is disclosed. The system comprises: a rotary tray configured to rotate about a vertical axis; a printing head, each having a plurality of separated nozzles; and a controller configured for controlling the inkjet printing head to dispense, during the rotation, droplets of building material in layers, such as to print a three-dimensional object on the tray.

Abstract: A method of three-dimensional fabrication of an object is disclosed. The method comprises: forming a plurality of layers in a configured pattern corresponding to the shape of the three-dimensional object, at least one layer of the plurality of layers being formed at a predetermined and different thickness selected so as to compensate for post-formation shrinkage of the layer along a vertical direction. In various exemplary embodiments of the invention spread of building material of one or more layers is diluted at least locally such as to maintain a predetermined thickness and a predetermined planar resolution for the layer.

Abstract: A system and a method of mitigating color discrepancies in three-dimensional (3D) printing systems may including a plurality of printing heads may include: printing one or more samples according to one or more sample parameters; obtaining a color offset vector from the one or more samples; receiving a model representing a 3D object, the model comprising a plurality of model printing points associated with respective color; analyzing the model in view of the obtained color offset vector to produce a calibrated data structure, adapted to mitigate color discrepancies; and printing the 3D object according to the calibrated data structure.

Abstract: A method of calibrating a print head of a printing system comprises applying voltage to the print head to effect a dispensing of liquid material from the print head; receiving, directly from a sensor within the print head, a signal correlative to a change in an amount of liquid in the print head; and varying the voltage responsively to the signal.

Abstract: Methods and systems (100) of printing a 3D object (101) comprising: depositing material, layer by layer, via printing heads (72) comprising one or more nozzle arrays; and activating each of said printing heads (72) to dispense a building material (50) at least once within a specified period of time during printing.

Abstract: A method of printing a three-dimensional (3D) color object, layer-by-layer, comprises: obtaining a 3D CAD specification defining a 3D geometry and a surface color distribution for the color object to be printed, defining regions on a surface of the color object; defining colors for each region based on the CAD specification; determining, using the 3D geometry of the specification, conditions applying at respective regions that are liable to cause color variation, such that using the colors as defined at the respective regions may give rise to a coloration error; selecting color corrections defined for respective determined conditions; correcting the defined colors; and printing the 3D color object with the color corrections.

Abstract: A method of additive manufacturing of a three-dimensional object is disclosed. The method comprises sequentially forming a plurality of layers each patterned according to the shape of a cross section of the object. In some embodiments, the formation of at least one of the layers comprises performing a raster scan to dispense at least a first building material composition, and a vector scan to dispense at least a second building material composition. The vector scan is optionally along a path selected to form at least one structure selected from the group consisting of (i) an elongated structure, (ii) a boundary structure at least partially surrounding an area filled with the first building material, and (iii) an inter-layer connecting structure.

Abstract: A tubular structure fabricated by additive manufacturing from non-biological building material formulations, and featuring an elongated core, a shell encapsulating the core and an intermediate shell between the core and the shell. Each of the core, the shell and the intermediate shell is made of a different material or a different combination of materials. Both the core and the intermediate shell are sacrificial. Additive manufacturing of the tubular structure is usable for fabricating an object featuring properties of a blood vessel.

Abstract: A system includes a plurality of building trays, a printing station, a powder delivery station, a powder spreading station, a process compaction station and a stage. The printing station prints a mask pattern on each of the plurality of building trays. The powder delivery station applies a dose of powder material on each of the plurality of building trays. The powder spreading station configured to spread the dose of powder material on each of the plurality of building trays. The process compaction station compacts the powder material. The stage concurrently advances the plurality of building trays to each of the stations to concurrently build a single layer on each the plurality of building trays and repeats the advancing to build a plurality of layers on each of the plurality of building trays. A three dimensional object is formed in each of the building trays.

Abstract: Novel support material formulations, characterized as providing a cured support material with improved dissolution rate, while maintaining sufficient mechanical strength, are disclosed. The formulations comprise a water-miscible non-curable polymer, a first water-miscible, curable material and a second, water-miscible material that is selected capable of interfering with intermolecular interactions between polymeric chains formed upon exposing the first water-miscible material to curing energy. Methods of fabricating a three-dimensional object, and a three-dimensional object fabricated thereby are also disclosed.

Abstract: Methods, particularly automated methods, are provided, as well as 3D-printed composite and hollow objects and 3D-printing systems for printing them. Methods comprise deriving a central line of a hollow 3D object model, calculating reference point(s) and/or line(s) along an inner surface of the hollow 3D object model, and filling the hollow 3D object model with material that comprises a thread defined with respect to the central line and the reference point(s) and/or line(s) and with filling material surrounding the thread. The support construction thus formed may be removed from the 3D object by pulling on the thread, extracting it and the surrounding support filling from the hollow object, thus enabling 3D-printing of convoluted or elongated hollow objects and objects with narrow openings. The parameters of the thread, such as type of curve and thickness, are selected to ensure thread extraction without risk of tearing or knotting the thread.