Production method for sintered valve guide

Abstract

A production method for a sintered valve guide includes preparing a raw powder which is primarily made of an iron powder and which includes at least a copper alloy powder and a graphite powder. The production method further includes compacting the raw powder into a green compact having an approximately cylindrical shape and sintering the green compact at 950 to 1050° C. The iron powder includes particles, which do not pass through a sieve of 240 mesh, at not less than 40 mass %, and not less than 70 mass % of the powder particles have not more than 0.5 of degree of circularity.

1 . A production method for a sintered valve guide, comprising:
 preparing a raw powder primarily made of an iron powder and including at least a copper alloy powder and a graphite powder;   compacting the raw powder into a green compact having an approximately cylindrical shape; and   sintering the green compact at 950 to 1050° C.,   wherein the iron powder includes particles, which do not pass through a sieve of 240 mesh, at not less than 40 mass %, and not less than 70 mass % of the powder particles have not more than 0.5 of degree of circularity.   
     
     
         2 . The production method for the sintered valve guide according to  claim 1 , wherein the iron powder consists of Fe and not more than 0.4 mass % of impurities, and the impurities include not more than 0.2 mass % of 0. 
     
     
         3 . The production method for the sintered valve guide according to  claim 1 , wherein the copper alloy powder is added to the raw powder so that the amount of Cu is 1 to 5 mass % with respect to the overall composition, and the graphite powder is added to the raw powder at 1.5 to 4 mass %. 
     
     
         4 . The production method for the sintered valve guide according to  claim 1 , wherein the raw powder includes an iron-phosphorous alloy powder so that the amount of P is 0.01 to 0.3 mass % with respect to the overall composition. 
     
     
         5 . The production method for the sintered valve guide according to  claim 1 , wherein the raw powder includes at least one of a manganese sulfide powder and a magnesium silicate mineral powder at not more than 1.6 mass %.