Assembly method of runner insert in water pump head

The invention discloses an assembly method of a runner insert in a water pump head. The assembly method comprises the following steps: (1) an insert is put in a mud core mold filled with sand; (2) the mud core mold with the insert is put in a lower mold of a sand casting mold, and then, an upper mold of the sand casting mold is covered; (3) molten iron is poured into the sand casting mold to be integrally fused with the mud core mold; meanwhile, the high temperature of the molten iron enables the reverse surface of the insert to be integrally joined with a mud core; and a finished product is primarily formed after the cooling; and (4) the primarily molded product is put in a sand casting machine to remove the mud core, not integrally bonded, in the pump head; and then, the surface of the pump head is smoothly polished to form the finished product. The surface roughness of the product, produced by the method, accords with requirements, and the product is high in levelness, so that the performance of a water pump can be guaranteed; and the insert and the water pump head are firm in connection, so that the dropping phenomenon is not generated, and the noise generated in use of the water pump can be prevented.