Method for achieving grain orientation

Abstract

Systems and methods for electrical component, e.g., brush, manufacture are provided that control grain orientation. The systems and methods utilize hot pressing techniques to enhance the properties and functionalities of the electrical components/brushes. An intermediate work product characterized by a grain orientation is initially formed through a conventional pressing technique. The conventionally-pressed intermediates are positioned within a cavity/die with the grain orientation in a predetermined orientation relative to the hot press force to be applied thereto. The hot pressed final product exhibits superior resistivity, strength and apparent density/durability. Surface features may be formed on the face(s) of the final work product during the hot pressing step that cannot be achieved in conventional processing techniques. Advantageous articles of manufacture, e.g., brushes and brush assemblies, are also disclosed.

1 . A method for fabricating a work piece, comprising:
 a. providing a powder mixture;   b. pressing the powder mixture to form an intermediate work product characterized by a grain orientation that is perpendicular to an axis defined by force application during said pressing;   c. orienting the intermediate work product in a cavity with the grain orientation in a predetermined alignment relative to a force axis to be applied to the cavity; and   d. hot pressing the intermediate work product to form a final work product.   
   
   
       2 . A method according to  claim 1 , wherein the powder mixture includes at least one of carbon and copper. 
   
   
       3 . A method according to  claim 1 , wherein the intermediate work product is characterized by a specific resistivity, break strength and apparent density. 
   
   
       4 . A method according to  claim 3 , wherein the final work product is characterized by (i) a specific resistivity that is less than the specific resistivity of the intermediate work product; (ii) a break strength that is greater than the break strength of the intermediate work product; and (iii) an apparent density that is greater than the apparent density of the intermediate work product. 
   
   
       5 . A method according to  claim 1 , wherein the intermediate work product is oriented in the hot pressed cavity such that the grain orientation is independent of the force axis. 
   
   
       6 . A method according to  claim 5 , wherein the intermediate work product is oriented in the cavity such that the grain orientation defines a circumferential or axial grain orientation after hot pressing. 
   
   
       7 . A method according to  claim 1 , wherein the intermediate work product is oriented in the cavity such that the grain orientation defines a tangential grain orientation after hot pressing. 
   
   
       8 . A method according to  claim 1 , further comprising positioning an ancillary component to be joined to the intermediate work product during hot pressing. 
   
   
       9 . A method according to  claim 8 , wherein the ancillary component is a lead wire. 
   
   
       10 . A method according to  claim 1 , further comprising positioning a plurality of intermediate work products in the cavity in side-by-side relation prior to hot pressing. 
   
   
       11 . A method according to  claim 10 , wherein the final work product is a multi-layer brush assembly. 
   
   
       12 . A method according to  claim 1 , wherein the cavity is adapted to form at least one surface feature on a face of the final work product during hot pressing. 
   
   
       13 . A method according to  claim 12 , wherein the at least one surface feature is formed on an end face of the final work product and is non-planar. 
   
   
       14 . A final work product fabricated according to the method of  claim 1 . 
   
   
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