Method for Molding Powder in Powder Metallurgy and Method for Producing Sintered Parts

Abstract

A mixed powder is obtained by adding at least one kind of solid ester wax to an iron-based powder for powder metallurgy use. The mixed powder is molded. The melting point of the ester wax is 100° C. or lower, the quantity of the ester wax added is in the range of 0.02 wt % or more to 0.6 wt % or less, and the temperature of the mold when the molding is performed is set in a range of (the melting point of the ester wax+10° C.) or more to 200° C. or less. The ester wax thereby liquefies on the surface of the mold and bleeds out when the molding is performed. As a result, molded sintered parts with complex shapes, good surface characteristics, and high densities can be easily obtained.

1 : A method for molding powder in powder metallurgy, comprising the steps of: 
 obtaining a mixed powder by adding at least one kind of solid ester wax to an iron-based powder for powder metallurgy use; and    molding said mixed powder at a temperature range of the melting point of said ester was+10° C. or more to 200° C. or less;    wherein the melting point of said ester wax ( 2 ) is 100° C. or lower, and the quantity of said ester wax ( 2 ) added is in a range of 0.02 wt % or more to 0.6 wt % or less.    
   
   
       2 : The method for molding powder in powder metallurgy in accordance with  claim 1 , wherein the acid value of said ester wax is 1.0 (mgKOH/g) or less and its hydroxyl group value is 4.0 (mgKOH/g) or less.  
   
   
       3 : The method for molding powder in powder metallurgy in accordance with  claim 1 , wherein said mixed powder comprises one or more solid lubricants selected from the group consisting of amide waxes, polyamide resins, and metal soaps, the melting points of said solid lubricants are at or above the temperature of said mold when the molding is performed, and the quantity of said solid lubricants added is in a range of more than 0 to 0.4 wt % or less.  
   
   
       4 : A method for producing sintered parts, comprising the step of sintering the molded article molded by the powder molding method described in  claim 1  at a temperature of 1000° C. or higher.  
   
   
       5 : A method for molding powder in powder metallurgy, comprising the steps of: 
 obtaining a mixed powder by adding at least one kind of solid ester wax to an iron-based powder for powder metallurgy use; and    molding said mixed powder;    wherein the melting point of said ester wax is 60° C. or lower, the quantity of said ester wax added is in a range of 0.02 wt % or more to 0.6 wt % or less, and cold molding is performed.    
   
   
       6 : The method for molding powder in powder metallurgy in accordance with  claim 5 , wherein the acid value of said ester wax is 1.0 (mgKOH/g) or less and its hydroxyl group value is 4.0 (mgKOH/g) or less.  
   
   
       7 : The method for molding powder in powder metallurgy in accordance with  claim 5 , wherein said mixed powder comprises one or more solid lubricants selected from the group consisting of amide waxes, polyamide resins, and metal soaps, the melting points of said solid lubricants are 60° C. or higher, and the quantity of said solid lubricants added is in a range of more than 0 to 0.4 wt % or less.  
   
   
       8 : A method for producing sintered parts, comprising the step of sintering the molded article molded by the powder molding method described in  claim 5  at a temperature of 1000° C. or higher.