PURPOSE: To improve the wear resistance and releasability of a mold by a method wherein the surface of a cavity, into which molding material is poured, is covered with the film made of tungsten carbide.
CONSTITUTION: A top mold 10 is equipped with a pair of cavity blocks 12 and 12 on both sides of its center block 11, while a bottom mold 20 is equipped with a pair of cavity blocks 22 and 22 on both sides of its center block 21. In this case, the under surface of the top mold cavity block 12 and the top surface of the bottom mold cavity block 22 are covered overall with the film made of ditungsten monocarbide. Concretely, tungsten carbide film 3 covers overall the respective surfaces of top mold cavity recesses 15, the bottom mold cavity recesses 25, sub-runners 26, gates 27 and air vents 28 by low temperature CVD method.
SAKAMOTO TOMOO
IWASAKI SEIICHI
