Patent ID: 7993123

Claim:
A system for fabricating a three dimensional model on a layer by layer basis, the system comprising: a drop-on-demand device for forming a mold of mold material; and a high deposition rate device for filling the mold with a model material at a rate faster than a rate at which the mold material is deposited, wherein the high deposition rate device comprises a spray device body having a model material path and an air flow path terminating in a nozzle for dispensing the model material a high flow rate, the model material path includes a model material inlet connectable solely to a model material supply, a model material flow restrictor for controlling a flow of model material through the model material passage, a model material passage, and a model material outlet connected from an output end of the model material passage, a model material passage temperature sensor for sensing a temperature of the model material in the model material flow passage, and a model material passage heating element, responsive to the model material temperature sensor, for controlling the temperature of the model material in the model material flow passage, the air flow path includes an air inlet connectable solely to an air supply, an air channel formed between the model material supply tube and the spray device body, an air outlet, an air flow path temperature sensor for sensing a temperature of an air flow in the air flow path, and an air flow path thermal control element, responsive to the air flow path temperature sensor, for controlling the temperature of the air flow in the air flow path, a cross sectional area of the air flow path is reduced, in a region of the air outlet, to cause an increase in speed of an air flow and a decrease of an air pressure in the region of the air outlet thereby to draw model material from the model material outlet and dispense a spray of model material from the nozzle.