Production tool to make abrasive particles with grooves

Abstract

Abrasive particles comprising shaped abrasive particles each having a sidewall, each of the shaped abrasive particles comprising alpha alumina and having a first face and a second face separated by a sidewall and having a maximum thickness, T; and the shaped abrasive particles further comprising a plurality of grooves on the second face.

What is claimed is: 
     
         1 . A plurality of shaped abrasive particles comprising alpha alumina and having an abrasives industry specified nominal grade or nominal screened grade, the shaped abrasive particles having a first face and a second face separated by a sidewall, wherein the sidewall forms a perimeter of the first face and second face, wherein at least 50% of the sidewall is planar such that it does not comprise areas that are convex from the first face to the second face, or areas that are concave from the first face to the second face. 
     
     
         2 . The plurality of shaped abrasive particles of  claim 1 , wherein at least 75% of the sidewall is planar. 
     
     
         3 . The plurality of shaped abrasive particles of  claim 2 , wherein at least 85% of the sidewall is planar. 
     
     
         4 . The plurality of shaped abrasive particles of  claim 1 , wherein, for substantially all cross sectional planes taken at 90 degrees to the sidewall, the meeting of the cross sectional plane and the sidewall comprises a substantially linear edge. 
     
     
         5 . The plurality of shaped abrasive particles of  claim 1  comprising an average tip radius of less than 75 microns, wherein the average tip radius is determined by measuring and averaging the radius of curvature of at least 30 apexes. 
     
     
         6 . The plurality of shaped abrasive particles of  claim 5 , wherein the average tip radius is less than 50 microns. 
     
     
         7 . The plurality of shaped abrasive particles of  claim 6 , wherein the average tip radius is less than 25 microns. 
     
     
         8 . The plurality of shaped abrasive particles of  claim 7 , wherein the average tip radius is less than 19.2 microns. 
     
     
         9 . The plurality of shaped abrasive particles of  claim 1 , wherein the shaped abrasive particles are made from a dispersion of aluminum oxide monohydrate that is gelled, molded to shape, dried to retain the shape, calcined, and then sintered. 
     
     
         10 . The plurality of shaped abrasive particles of  claim 1 , wherein the perimeter of the first face and second face a geometric shape, and the first face and the second face have the same geometric shape. 
     
     
         11 . The plurality of shaped abrasive particles of  claim 10 , wherein the geometric shape is substantially triangular. 
     
     
         12 . The plurality of shaped abrasive particles of  claim 11 , wherein the geometric shape is an equilateral triangle. 
     
     
         13 . The plurality of shaped abrasive particles of  claim 10 , wherein the geometric shape is a star. 
     
     
         14 . The plurality of shaped abrasive particles of  claim 1  comprising a draft angle α between the second face and the sidewall. 
     
     
         15 . The plurality of shaped abrasive particles of  claim 14 , wherein the draft angle α is 90 degrees. 
     
     
         16 . The plurality of shaped abrasive particles of  claim 14 , wherein the draft angle α is in a range from 95 degrees to 130 degrees. 
     
     
         17 . A method of making the plurality of shaped abrasive particles comprising:
 filling shaped mold cavities of a production tool with a dispersion of aluminum oxide monohydrate;   drying the dispersion in the shaped mold cavities to form precursor shaped abrasive particles that retain the shape of the mold cavities;   removing the precursor shaped abrasive particles from the mold cavities;   calcining and sintering the precursor shaped abrasive particles to form the plurality of shaped abrasive particles having a first face and a second face separated by a sidewall, wherein the sidewall forms a perimeter of the first face and second face, wherein at least 50% of the sidewall is planar such that it does not comprise areas that are convex from the first face to the second face, or areas that are concave from the first face to the second face.   
     
     
         18 . The method of  claim 17 , wherein the mold cavities comprise a mold cavity sidewall that forms a mold cavity perimeter having a geometric shape. 
     
     
         19 . The method of  claim 18 , wherein the geometric shape is substantially triangular. 
     
     
         20 . The method of  claim 18 , wherein the geometric shape is a star.