MOLD FOR CASTING

PURPOSE:To prevent oxidation of iron and steel by the Al2O3 film on the outside surface produced during charging and to prevent the failure and erosion of a sprue system by constituting the sprue system of an iron or steel material which is subjected to an Al diffusion coating treatment. CONSTITUTION:A sprue system is constituted of an Al-diffusion coated straight pipe 7 of a long sized pipe of one body constituting a sprue 2, and an Al-diffusion-coated pipe 7' of a J shape constituted with a sprue bottom 2', a runner 2'' and a gate 2''' in one body. The pipe 7 is reinforced with a lightweight steel pipe 8 for reinforcement from the outer side, and the pipe 7' is embedded in sand 6''. Thus the sprue 2 is formed of the lightweight steel pipe 8 for reinforcement without using conventional thick-walled heavy metallic frames and does not require the use of backing sand for fixing the pipe 7 at all.