The automotive industry is one of the most important customers for the foundry industry. In particular, casting of engine parts for combustion engines is one of the most demanding areas of casting technology. New generation of engine blocks and cylinder heads are getting geometrically more complicated in order to maintain or even increase performance. With the increased complexity, the strain for the casting molds is growing and the widely used technology of core making with standard silica sands is, for several applications, no longer reaching the demanded results. Furthermore, in last decade, there has been an eort in using inorganic binders in core making process, which brings along some additional technological challenges. In order to cope with these challenges, in this paper, silica and non-silica sands with round and angular grains as well as with fine and coarse grains are examined using an inorganic binder for strength, permeability, and thermal stability. The results shall provide useful information about the possibilities of application and combining dierent types of foundry sands, both silica and non-silica. With their impact on the selected sand core properties, they can help in solving problems in the core making process as well as reaching a high quality of the final product-casting.
The main component of each sand mold is the base molding material, foundry sand, which is usually up to 98% of the whole mass depending on the used technology. For the production of molds or cores, natural or synthetic grains can be used . Foundry sand is, according to the authors of , defined as granular refractory material with grains of sizes in a range from 0.02 mm to 2 mm. The most important foundry sand used is silica sand. The main component is quartz, a crystalline form of SiO2. Silica sand is available in good quality in central Europe, which forms the basis for wide use in the foundry industry. However, silica sand has some negative properties, which can result in problems when producing high-quality cast parts. Practical experience and molding data show that 40–70% of the casting defects arise from inadequate mold properties . The main disadvantage of silica sand is the thermal expansion behavior as a result of a phase transition.