Control of metallic electrohydrodynamic three-dimensional printing using feedback of surface characteristics

Abstract

A metallic electrohydrodynamic (EHD) three-dimensional printer fabricates an object while surface characteristics of the object are monitored. Sensors acquire data on surface characteristics, and feedback related to these surface characteristics is used to adjust the fabrication process, e.g., where the surface characteristics deviate from a target surface shape.

What is claimed is: 
     
         1 . A method for additive manufacturing comprising:
 fabricating an object based on a three-dimensional model with a printer, wherein the printer is a three-dimensional metallic printer configured to additively manufacture the object with a number of droplets of liquefied metal as a build material using a metallic liquid expeller;   acquiring surface data from the object with one or more sensors during fabrication, the surface data characterizing a location on a layer of a build material of the object deposited by the printer;   estimating a target surface shape for the build material at the location based on the three-dimensional model;   comparing the surface data to the target surface shape at the location; and   adjusting a fabrication process when a discrepancy is identified between the surface data and the target surface shape.   
     
     
         2 . The method of  claim 1 , wherein the metallic liquid expeller is configured to drive the droplets of liquefied metal by applying an electrostatic field to a meniscus of the liquefied metal extending from an outlet of the metallic liquid expeller of the printer. 
     
     
         3 . The method of  claim 1 , wherein the surface data is acquired for each one of the droplets of liquefied metal. 
     
     
         4 . The method of  claim 1 , wherein the surface data is acquired for a surface region about the location. 
     
     
         5 . The method of  claim 1 , wherein the surface data is acquired for a voxel about the location. 
     
     
         6 . The method of  claim 1 , further comprising capturing process data characterizing the droplets of liquefied metal. 
     
     
         7 . The method of  claim 6 , wherein the process data includes at least one of a volume of one of the droplets of liquefied metal and an average volume of the droplets of liquefied metal. 
     
     
         8 . The method of  claim 6 , wherein the process data includes at least one of a dimension of one of the droplets of liquefied metal and an average dimension of the droplets of liquefied metal. 
     
     
         9 . The method of  claim 6 , wherein the process data includes at least one of a velocity of one of the droplets of liquefied metal and an average velocity of the droplets of liquefied metal. 
     
     
         10 . The method of  claim 6 , wherein the process data includes at least one of a temperature of one of the droplets of liquefied metal and an average temperature of the droplets of liquefied metal. 
     
     
         11 . The method of  claim 6 , wherein the process data includes at least one of a distance between an expeller of the printer and the layer of the build material, a temperature of a build chamber of the printer, and a temperature of a print bed of the printer. 
     
     
         12 . The method of  claim 1 , wherein the one or more sensors include at least one of a contact profilometer and a non-contact profilometer. 
     
     
         13 . The method of  claim 12 , wherein the one or more sensors include an optical profilometer. 
     
     
         14 . The method of  claim 1 , wherein the discrepancy includes a depression at a position in the layer of the build material, and wherein adjusting the fabrication process includes repeating a deposition of droplets of liquefied metal at the position. 
     
     
         15 . The method of  claim 1 , wherein the discrepancy includes a protrusion at a position in the surface of the layer of the object, and wherein adjusting the fabrication process includes omitting a deposition of droplets of liquefied metal at the position while fabricating a second layer of the object on the layer containing the protrusion. 
     
     
         16 . The method of  claim 1 , further comprising refinishing the location on the layer of the object when the discrepancy between the surface data and the target surface shape exceeds a predetermined threshold. 
     
     
         17 . The method of  claim 1 , further comprising sending a notification to a user of the printer when the discrepancy between the surface data and the target surface shape exceeds a predetermined threshold. 
     
     
         18 . The method of  claim 1 , further comprising acquiring parameter data related to at least one parameter or condition of the printer present during fabrication of the layer of the build material. 
     
     
         19 . A computer program product comprising computer executable code embodied in a non-transitory computer-readable medium that, when executing on one or more computing devices in electronic communication with a three-dimensional metallic printer configured to additively manufacture an object based on a three-dimensional model with a number of droplets of liquefied metal as a build material using a metallic liquid expeller, performs the steps of:
 acquiring surface data from the object with one or more sensors during fabrication, the surface data characterizing a location on a layer of a build material of the object deposited by the three-dimensional metallic printer;   estimating a target surface shape for the build material at the location based on the three-dimensional model;   comparing the surface data to the target surface shape at the location; and   adjusting a fabrication process of the three-dimensional metallic printer when a discrepancy is identified between the surface data and the target surface shape.   
     
     
         20 . An additive manufacturing system including:
 a three-dimensional metallic printer configured to additively manufacture an object based on a three-dimensional model with a number of droplets of liquefied metal as a build material using a metallic liquid expeller; and   a controller in electronic communication with the three-dimensional metallic printer over a data network, the controller including a processor and a memory, the memory bearing computer executable code configured to perform the steps of acquiring surface data from the object with one or more sensors during fabrication, the surface data characterizing a location on a layer of a build material of the object deposited by the three-dimensional metallic printer, estimating a target surface shape for the build material at the location based on the three-dimensional model, comparing the surface data to the target surface shape at the location, and adjusting a fabrication process of the three-dimensional metallic printer when a discrepancy is identified between the surface data and the target surface shape.