Mold for metal injection molding

Abstract

There is provided a metal injection molding method for producing a molded part. A polymeric binder and a metallic powder are mixed to obtain a powder-binder mixture. The powder-binder mixture is heated to a desired temperature. The powder-binder mixture is injected in a polymer mold at a desired pressure and/or a desired flow rate. The polymer mold has a portion of its internal surface coated with a metallic layer. And finally the molded part is demolded. There is further provided a metal injection mold comprising a polymer plate having a mold surface, and a metallic layer on a portion or the totality of the mold surface.

1 . A metal injection molding method for producing a molded part comprising:
 mixing a polymeric binder and a metallic powder to obtain a powder-binder mixture;   heating the powder-binder mixture to a desired temperature;   injecting the powder-binder mixture in a polymer mold at a desired pressure and/or a desired flow rate, the polymer mold having a portion of its internal surface coated with a metallic layer; and   demolding the molded part.   
     
     
         2 . The metal injection molding method of  claim 1 , further comprising, after the demolding, sintering the molded part. 
     
     
         3 . The metal injection molding method of  claim 1 , wherein the metal injection molding is low-pressure powder injection molding and the desired pressure is equal to or below 5 MPa. 
     
     
         4 . The metal injection molding of  claim 1 , wherein the desired temperature is from 60° C. to 180° C. 
     
     
         5 . The metal injection molding method of  claim 1 , further comprising before the step of mixing, heating the polymeric binder and the metallic powder. 
     
     
         6 . The metal injection molding method of  claim 1 , further comprising before the step of injecting, cooling or heating the polymer mold. 
     
     
         7 . The metal injection molding method of  claim 1 , wherein the metallic layer has a thickness of from 100 nm to 200 nm. 
     
     
         8 . The metal injection molding method of  claim 1 , wherein the metallic layer comprises chromium, silver, cobalt, copper, iron, molybdenum, nickel, palladium, platinum, tungsten, or gold. 
     
     
         9 . The metal injection molding method of  claim 1 , wherein the polymer mold is selected from polytetraluoroethylene, polycarbonate and polyethylene. 
     
     
         10 . The metal injection molding method of  claim 2 , wherein the polymeric binder comprises low density polyethylene, paraffin wax, stearic acid, ethylene-vinyl acetate, beeswax, polypropylene, or polystyrene. 
     
     
         11 . The metal injection molding method of  claim 2 , wherein the metallic powder is selected from a titanium alloy, a nickel alloy, an aluminum alloy, a stainless steel alloy, a nickel-based superalloy, and/or a steel alloy. 
     
     
         12 . The metal injection molding method of  claim 1 , wherein the portion of the internal surface coated with the metallic layer has two opposite internal walls at a distance of less than 15 mm. 
     
     
         13 . The metal injection molding method of  claim 12 , wherein the distance is less than 1 mm. 
     
     
         14 . The metal injection molding method of  claim 1 , wherein the portion of the internal surface coated with the metallic layer has two adjacent walls at an angle equal to or less than 75°. 
     
     
         15 . The metal injection molding method of  claim 14 , wherein the angle is equal to or less than 60°. 
     
     
         16 . A metal injection mold comprising a polymer plate having a mold surface defining a mold cavity, and a metallic layer on a portion or the totality of the mold surface. 
     
     
         17 . The metal injection mold of  claim 16 , wherein the thickness of the metallic layer is from 100 to 200 nm. 
     
     
         18 . The metal injection mold of  claim 16 , wherein the portion of the mold surface is a protrusion or a cavity. 
     
     
         19 . The metal injection mold of  claim 16 , wherein the portion of the mold surface has two opposite internal walls of the mold surface being less than 15 mm apart. 
     
     
         20 . The metal injection mold of  claim 16 , wherein the portion of the mold surface has two internal adjacent walls of the mold surface positioned at an angle of less than 75°.