Method and apparatus associated with anisotropic shrink in sintered ceramic items

Abstract

A manufacturing method for producing ceramic item from a photocurable ceramic filled material by stereolithography. The method compensates for the anisotropic shrinkage of the item during firing to produce a dimensionally accurate item.

1 .- 56 . (canceled) 
     
     
         57 . A method, comprising:
 representing an item including its dimensions relative to a three dimensional coordinate system, the item adapted to be formed as a green ceramic item in a stereolithography apparatus from a photo-polymerizable material including ceramic particles;   applying three unequal scaling factors to the dimensions to compensate for the anisotropic shrinkage of the green ceramic item relative to the axes of the coordinate system upon the green ceramic item being sintered;   building the green ceramic item in the stereolithography apparatus after said applying; and   heating the green ceramic item to form a sintered ceramic item substantially conforming to the dimensions.   
     
     
         58 . The method of  claim 57 , further comprising applying a largest scaling value to one of the unequal scaling factors corresponding to a build direction. 
     
     
         59 . The method of  claim 57 , wherein said building includes forming a plurality of layers of the photo-polymerizable material; and
 which further includes leveling at least one of the plurality of layers of the photo-polymerizable material prior to forming the next of the plurality of layers of the photo-polymerizable material; and   which further includes exposing the at least one of the plurality of layers of the photo-polymerizable material with a dose of energy prior to forming the next of the plurality of layers of the photo-polymerizable material.   
     
     
         60 . The method of  claim 59 , wherein said leveling including mechanically wiping a surface of the at least one of the plurality of layers of the photo-polymerizable material. 
     
     
         61 . The method of  claim 60 , wherein said mechanically wiping changes the homogeneity of the ceramic particles in at least two dimensions. 
     
     
         62 . The method of  claim 60 , wherein said leveling includes leveling each of the plurality of layers of the photo-polymerizable material; and
 which further includes exposing each of the plurality of layers of the photo-polymerizable material with a dose of energy.   
     
     
         63 . The method of  claim 57 , wherein the stereolothography apparatus includes a machine three dimensional coordinate system coextensive with the three dimensional coordinate system. 
     
     
         64 . The method of  claim 57 , wherein the sintered ceramic item is of a near net shape. 
     
     
         65 . The method of  claim 57 , wherein the sintered ceramic item is of a net shape. 
     
     
         66 . The method of  claim 57 , wherein the sintered ceramic item is dimensionally accurate with the dimensions within about 1.5%. 
     
     
         67 . The method of  claim 57 , wherein the sintered ceramic item is dimensionally accurate with the dimensions within about 0.5%. 
     
     
         68 . The method of  claim 57 , wherein said heating includes burning off a polymer in the green ceramic item. 
     
     
         69 . The method of  claim 58 , wherein the three dimensional coordinate system is a Cartesian coordinate system including a first axis corresponding to the X axis and a second axis corresponding to the Y axis and a third axis corresponding to the Z axis;
 wherein the stereolothography apparatus includes a machine three dimensional coordinate system coextensive with the three dimensional coordinate system;
 which further includes selecting a build direction corresponding to the Z axis; 
 wherein said building includes forming a plurality of layers from the photo-polymerizable material in the build direction; and 
 which further includes wiping an upper surface of each of the plurality of layers of the photo-polymerizable material prior to being exposed to an energy dose, said wiping in the direction of one of the other axes. 
   
     
     
         70 . The method of  claim 57 , wherein the photo-polymerizable material includes ceramic particles within a range of 35% to 65% by volume. 
     
     
         71 . The method of  claim 57 , wherein said representing is associated with any of electronic data, digital data, virtual data, computer files, solid body modeling, computer modeling, computer aided manufacturing. 
     
     
         72 . The method of  claim 57 , wherein said heating is to a temperature within a range of about 1100° C. to 1700° C. 
     
     
         73 . A method, comprising:
 defining the original dimensions of an item with reference to a three dimensional coordinate system associated with a stereolithography apparatus, the coordinate system including a first direction, a second direction, and a third direction;   applying a first factor to increase the original dimensions of the item defined relative to the first direction;   applying a second factor to increase the original dimensions of the item defined relative to the second direction;   applying a third factor to increase the original dimensions of the item defined relative to the third direction;   wherein the third direction corresponds to a build direction, and wherein the factors are not equal;   building a green ceramic item by stereolithography from a photo-polymerizable resin including ceramic particles, said building utilizing the increased dimensions from said applying acts to control the dimensions of the green ceramic item; and   sintering the green ceramic item to form a sintered ceramic item, wherein the sintered ceramic item has dimensions corresponding substantially to the original dimensions of the item.   
     
     
         74 . The method of  claim 73 , wherein said third factor is a largest one of the factors. 
     
     
         75 . The method of  claim 73 , wherein the sintered ceramic item is dimensionally accurate with the dimensions within about 1.5%. 
     
     
         76 . The method of  claim 73 , wherein the sintered ceramic item is dimensionally accurate with the dimensions within about 0.5%.