During, in order to be used repeatedly 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.
Sand casting pattern is very important in sand mold casting. Sand casting pattern may be made as one-piece or multiple-piece like split and match plate. In sand mold casting, 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 pattern surfaces are never made perpendicular to the mold parting surface. The taper of the pattern surface, which provides narrowing the mold cavity towards the mold parting surface is called draft. 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%.
So after the sand casting pattern we prepared well, the design of the sand casting can form a through way to sand mold. The sand cores we made can guarantee this process. The passage ways in sand mold casting are formed by the cores which are placed very well. We pour the metal into the mold cavity until the metal solidify. So the sand casting pattern we adopted in sand mold casting can affect the whole.