The Study of the Influence of Core Mixtures with Varying Ratios of Foundry Sand

Abstract Core mixture preparation plays a crucial role in the manufacturing process for achieving acceptable products that meet the required quality standards. The use of pure quartz sand consistently results in surface defects on castings. Therefore, ongoing efforts are made to identify new methods to prevent these defects. One such approach involves the addition of non-quartz sands to the core mixtures. This article presents the results of testing the physico-chemical properties of quartz and non-quartz sands, as well as their mixtures in various ratios, on the surface quality of cast iron castings. The tests were conducted on five types of foundry sands and twelve core mixtures, with 90%, 60%, and 30% quartz sand content. In addition to determining the chemical composition of the sands using AAS elemental analysis, other parameters such as loss on ignition, bulk density, porosity, thermal dilatation, sieve analysis, bending strength, and the surface quality of 24 castings were examined. The results indicate that the presence of acidic SiO2 oxides in the sands, lower bulk density and porosity, irregular thermal expansion of sands, higher mean grain size (d50), lower grain size regularity, and lower bending strength increase the risk of veinings. Properties such as loss on ignition, sand porosity, AFS value, content of particles below 0.09 mm, log w, Sth, MKcalc, nth, Sw, Kh, and the proportion of coarse, medium, fine, and very fine particles were found to have no significant impact on the veining elimination.