Water Absorption and Water Retention in Oolitics

Sand inclusion and gas defect are main defects of green sand castings and both are related to with moisture in green sand. It’s quantity of the moisture changes during and after mixing. In this study, the relationship between moisture and oolitics is observed. Moist oolitics has high compactability and low evaporation during and after mixing than moistless oolitics. A cross section of sand adhered with oolitics was observed by SEM. (Porous structures were seen, and these structures coated were found to store moisture when with bentonite.) That is why dryness is prevented. Moistless oolitics require a long time for mixing and have low compactability because they need extra time for moisture to move into porous structure. It is therefore very important that oolitics are moistened before mixing