Fabrication of alloy variant structures using direct metal deposition

Abstract

Direct-metal deposition (DMD), preferably under closed-loop control, is used to fabricate alloy-variant material structures which provide a combination of desirable physical and mechanical properties. Use of the invention facilitates the production of high-strength, high-wear, and impact-resistant structures which decrease the likelihood of erosion, heat checking and brittle failure in injection molds, die casting, thixomolding and other, more exotic tooling. The invention uses DMD to deposit a first material or alloy in an area exposed to high wear, such as the tooling gate area, with a second material or alloy being used elsewhere in the tool for greater impact resistance. Advantageously, the areas may be of a user-defined thickness to further improve longevity. The resulting composite material structure has mechanical properties (i.e., yield strength, hardness and abrasion resistance) which exceed that of the homogeneous compositions currently used for mold materials, thereby enhancing productivity while improving part quality in these and other applications.

We claim:  
     
         1 . A improved tooling fabrication method, comprising the steps of: 
 depositing a first metallic or ceramic alloy using a laser-assisted direct metal deposition process in a first region of the tooling requiring high thermal or wear resistance; and    depositing a second metallic or ceramic alloy using a laser-assisted direct metal deposition process in a second area of the tooling requiring high strength or impact resistance.    
     
     
         2 . The method of  claim 1 , wherein the tooling is used in injection molding, die casting, or thixomolding.  
     
     
         3 . The method of  claim 1 , wherein: 
 the tooling includes a gate area; and    the first metallic or ceramic alloy is deposited relative to the gate area.    
     
     
         4 . The method of  claim 1 , wherein: 
 the tooling includes in interface associated with opening and closing; and    the second metallic or ceramic alloy is deposited relative to interface.    
     
     
         5 . The method of  claim 1 , wherein: 
 the tooling is die-cast mold having a gate area;    H19 steel is used in conjunction with the fabrication of the gate area; and    H13 steel is used in conjunction with the fabrication of non-gate areas.