System and method for enabling fused deposition metal 3d printing

Abstract

A metal fused, deposition printer, that uses the thixotropic (or other) properties of a metal (or alloy) to control the viscosity of the material being deposited. In the invention presented in this patent, the viscosity of the metal is controlled by shearing it before, during, or after the deposition process. Since thixotropic (or other) properties allow for the control of the viscosity separately from the temperature, the taught invention allows for precise control of the temperature differential between the layer being deposited, and the substrate layer.

1 .- 16 . (canceled) 
     
     
         17 . A method comprising:
 melting a metal into a slurry using a liquefier comprising both a heating element and a shearing device;   independently controlling the heating element and the shearing device to cause the metal to have a first temperature and to achieve a viscosity within a thixotropic range;   dispensing, utilizing an extrusion nozzle in communication with the liquefier, the slurry onto a substrate at a second temperature; and   moving the extrusion nozzle as the slurry is deposited,   wherein the first temperature is substantially the same as the second temperature.   
     
     
         18 . The method of  claim 17 , wherein:
 the extrusion nozzle and the substrate are disposed within a chamber, and   the method further comprises controlling a temperature of the chamber.   
     
     
         19 . The method of  claim 17 , further comprising:
 after the slurry is deposited, shaking the substrate so as to control a viscosity of the deposited slurry.   
     
     
         20 . The method of  claim 17 , wherein the liquefier comprises a screw that feeds chips of the metal, powder of the metal, or both chips and powder of the metal to the heating element. 
     
     
         21 . The method of  claim 17 , wherein the controlling of the shearing device causes the metal to achieve the viscosity before it exits the extrusion nozzle. 
     
     
         22 . The method of  claim 21 , wherein the controlling of the shearing device to achieve the viscosity comprises (i) using one or more rotating arms, (ii) forcing the metal through a narrow opening, or (iii) both (i) and (ii). 
     
     
         23 . The method of  claim 21 , wherein the controlling of the shearing device to achieve the viscosity comprises shaking the metal within the liquefier. 
     
     
         24 . A system for metal fused deposition 3-D printing, comprising:
 a printing chamber operable to maintain a temperature therein;   a multi-axis positioning table disposed in the printing chamber and comprising a printing substrate;   a liquefier comprising a heating element and a shearing device, the heating element and the shearing device being independently controllable to affect properties of a metal printing material;   a controller operatively coupled to the printing chamber and the liquefier, the controller being configured to:
 control the liquefier such that the metal printing material has a first temperature and a viscosity in a thixotropic range of the metal printing material; and 
 control the printing chamber such that the substrate has a second temperature substantially the same as the first temperature; and 
   an extrusion nozzle coupled to receive the metal printing material from the liquefier and deposit the metal printing material on the substrate.   
     
     
         25 . The system of  claim 24 , wherein the extrusion nozzle is constructed from an iron-rich alloy. 
     
     
         26 . The system of  claim 24 , wherein printing chamber comprises an airtight chamber housing an inert gas. 
     
     
         27 . The system of  claim 24 , further comprising:
 a drive wire, a drive screw, or both a drive wire and a drive screw operable to control a speed of deposition of the metal printing material onto the substrate.   
     
     
         28 . The system of  claim 24 , wherein the metal printing material comprises a magnesium alloy. 
     
     
         29 . The system of  claim 28 , wherein the magnesium alloy comprises an AZ91D alloy.