Patent ID: 8727672

Claim:
A method comprising: forming three dimension objects comprising the steps of: 1) providing a device for conveying particulate material comprising: a) a reservoir; b) a spreader unit; and c) a plurality of particulate material conveying systems including a first particulate material conveying system having a screw conveyor and a second particulate material conveying system having a screw conveyor; 2) forming a first layer of the three dimension object by a layer forming step comprising: a) conveying the particulate material out of the reservoir into the spreader unit with at least the first particulate material conveying system; b) spreading the particulate material unit unto a build platform with the spreader; and c) conveying excess particulate material that was fed to the spreader unit back into the reservoir after the step of spreading; and 3) forming a second layer of the three dimensional object by a layer forming step by repeating steps 2 a , 2 b and 2 c; wherein the steps 2 a and 2 c of conveying takes place in a closed conveying circuit that includes the plurality of particulate material conveying systems.