During sand mold casting, sand casting pattern are made of relatively tough materials. There are many sand casting pattern materials such like wood, metal, and plastic. A parting and releasing agent is applied on the pattern surface so it can provide a easy removal of the pattern from the mold, and the sand casting pattern we used are commonly made larger than the casting because of the shrinkage effect we have to consider of. Generally the shrinkage allowances are usually 1-2%. The draft can allow us have a easy removal of the pattern and the casting from the sand mold. The draft angle is commonly adopt 1-3%.
FHZL 3D printing technology can save the mold cost and save the mold making time, we print the sand core and sand pattern by 3d printing machine directly. The multiple valve galleries also produced by sand 3d printing. We prepare the sand pattern well and pour the fluid into the mold cavity until the metal solidify. The job is pretty challenging because different sizes of passage way inside and the variable thickness can cause crack and porosity and hot spot defect.